get('system.cron_last'); * // Set the cron run time to the current request time. * $state->set('system.cron_last', REQUEST_TIME); * @endcode * * For more on the State API, see https://www.drupal.org/developing/api/8/state * @} */ /** * @defgroup config_api Configuration API * @{ * Information about the Configuration API. * * The Configuration API is one of several methods in Drupal for storing * information. See the @link info_types Information types topic @endlink for * an overview of the different types of information. The sections below have * more information about the configuration API; see * https://www.drupal.org/developing/api/8/configuration for more details. * * @section sec_storage Configuration storage * In Drupal, there is a concept of the "active" configuration, which is the * configuration that is currently in use for a site. The storage used for the * active configuration is configurable: it could be in the database, in files * in a particular directory, or in other storage backends; the default storage * is in the database. Module developers must use the configuration API to * access the active configuration, rather than being concerned about the * details of where and how it is stored. * * Configuration is divided into individual objects, each of which has a * unique name or key. Some modules will have only one configuration object, * typically called 'mymodule.settings'; some modules will have many. Within * a configuration object, configuration settings have data types (integer, * string, Boolean, etc.) and settings can also exist in a nested hierarchy, * known as a "mapping". * * Configuration can also be overridden on a global, per-language, or * per-module basis. See https://www.drupal.org/node/1928898 for more * information. * * @section sec_yaml Configuration YAML files * Whether or not configuration files are being used for the active * configuration storage on a particular site, configuration files are always * used for: * - Defining the default configuration for an extension (module, theme, or * profile), which is imported to the active storage when the extension is * enabled. These configuration items are located in the config/install * sub-directory of the extension. Note that changes to this configuration * after a module or theme is already enabled have no effect; to make a * configuration change after a module or theme is enabled, you would need to * uninstall/reinstall or use a hook_update_N() function. * - Defining optional configuration for a module or theme. Optional * configuration items are located in the config/optional sub-directory of the * extension. These configuration items have dependencies that are not * explicit dependencies of the extension, so they are only installed if all * dependencies are met. For example, in the scenario that module A defines a * dependency which requires module B, but module A is installed first and * module B some time later, then module A's config/optional directory will be * scanned at that time for newly met dependencies, and the configuration will * be installed then. If module B is never installed, the configuration item * will not be installed either. * - Exporting and importing configuration. * * The file storage format for configuration information in Drupal is * @link http://wikipedia.org/wiki/YAML YAML files. @endlink Configuration is * divided into files, each containing one configuration object. The file name * for a configuration object is equal to the unique name of the configuration, * with a '.yml' extension. The default configuration files for each module are * placed in the config/install directory under the top-level module directory, * so look there in most Core modules for examples. * * @section sec_schema Configuration schema and translation * Each configuration file has a specific structure, which is expressed as a * YAML-based configuration schema. The configuration schema details the * structure of the configuration, its data types, and which of its values need * to be translatable. Each module needs to define its configuration schema in * files in the config/schema directory under the top-level module directory, so * look there in most Core modules for examples. * * Configuration can be internationalized; see the * @link i18n Internationalization topic @endlink for more information. Data * types label, text, and date_format in configuration schema are translatable; * string is non-translatable text (the 'translatable' property on a schema * data type definition indicates that it is translatable). * * @section sec_simple Simple configuration * The simple configuration API should be used for information that will always * have exactly one copy or version. For instance, if your module has a * setting that is either on or off, then this is only defined once, and it * would be a Boolean-valued simple configuration setting. * * The first task in using the simple configuration API is to define the * configuration file structure, file name, and schema of your settings (see * @ref sec_yaml above). Once you have done that, you can retrieve the active * configuration object that corresponds to configuration file mymodule.foo.yml * with a call to: * @code * $config = \Drupal::config('mymodule.foo'); * @endcode * * This will be an object of class \Drupal\Core\Config\Config, which has methods * for getting configuration information. For instance, if your YAML file * structure looks like this: * @code * enabled: '0' * bar: * baz: 'string1' * boo: 34 * @endcode * you can make calls such as: * @code * // Get a single value. * $enabled = $config->get('enabled'); * // Get an associative array. * $bar = $config->get('bar'); * // Get one element of the array. * $bar_baz = $config->get('bar.baz'); * @endcode * * The Config object that was obtained and used in the previous examples does * not allow you to change configuration. If you want to change configuration, * you will instead need to get the Config object by making a call to * getEditable() on the config factory: * @code * $config =\Drupal::service('config.factory')->getEditable('mymodule.foo'); * @endcode * * Individual configuration values can be changed or added using the set() * method and saved using the save() method: * @code * // Set a scalar value. * $config->set('enabled', 1); * // Save the configuration. * $config->save(); * @endcode * * Configuration values can also be unset using the clear() method, which is * also chainable: * @code * $config->clear('bar.boo')->save(); * $config_data = $config->get('bar'); * @endcode * In this example $config_data would return an array with one key - 'baz' - * because 'boo' was unset. * * @section sec_entity Configuration entities * In contrast to the simple configuration settings described in the previous * section, if your module allows users to create zero or more items (where * "items" are things like content type definitions, view definitions, and the * like), then you need to define a configuration entity type to store your * configuration. Creating an entity type, loading entities, and querying them * are outlined in the @link entity_api Entity API topic. @endlink Here are a * few additional steps and notes specific to configuration entities: * - For examples, look for classes that implement * \Drupal\Core\Config\Entity\ConfigEntityInterface -- one good example is * the \Drupal\user\Entity\Role entity type. * - In the entity type annotation, you will need to define a 'config_prefix' * string. When Drupal stores a configuration item, it will be given a name * composed of your module name, your chosen config prefix, and the ID of * the individual item, separated by '.'. For example, in the Role entity, * the config prefix is 'role', so one configuration item might be named * user.role.anonymous, with configuration file user.role.anonymous.yml. * - You will need to define the schema for your configuration in your * modulename.schema.yml file, with an entry for 'modulename.config_prefix.*'. * For example, for the Role entity, the file user.schema.yml has an entry * user.role.*; see @ref sec_yaml above for more information. * - Your module can provide default/optional configuration entities in YAML * files; see @ref sec_yaml above for more information. * - Some configuration entities have dependencies on other configuration * entities, and module developers need to consider this so that configuration * can be imported, uninstalled, and synchronized in the right order. For * example, a field display configuration entity would need to depend on * field configuration, which depends on field and bundle configuration. * Configuration entity classes expose dependencies by overriding the * \Drupal\Core\Config\Entity\ConfigEntityInterface::calculateDependencies() * method. * - On routes for paths starting with '/admin' or otherwise designated as * administration paths (such as node editing when it is set as an admin * operation), if they have configuration entity placeholders, configuration * entities are normally loaded in their original language, without * translations or other overrides. This is usually desirable, because most * admin paths are for editing configuration, and you need that to be in the * source language and to lack possibly dynamic overrides. If for some reason * you need to have your configuration entity loaded in the currently-selected * language on an admin path (for instance, if you go to * example.com/es/admin/your_path and you need the entity to be in Spanish), * then you can add a 'with_config_overrides' parameter option to your route. * The same applies if you need to load the entity with overrides (or * translated) on an admin path like '/node/add/article' (when configured to * be an admin path). Here's an example using the configurable_language config * entity: * @code * mymodule.myroute: * path: '/admin/mypath/{configurable_language}' * defaults: * _controller: '\Drupal\mymodule\MyController::myMethod' * options: * parameters: * configurable_language: * type: entity:configurable_language * with_config_overrides: TRUE * @endcode * With the route defined this way, the $configurable_language parameter to * your controller method will come in translated to the current language. * Without the parameter options section, it would be in the original * language, untranslated. * * @see i18n * * @} */ /** * @defgroup cache Cache API * @{ * Information about the Drupal Cache API * * @section basics Basics * * Note: If not specified, all of the methods mentioned here belong to * \Drupal\Core\Cache\CacheBackendInterface. * * The Cache API is used to store data that takes a long time to compute. * Caching can either be permanent or valid only for a certain timespan, and * the cache can contain any type of data. * * To use the Cache API: * - Request a cache object through \Drupal::cache() or by injecting a cache * service. * - Define a Cache ID (cid) value for your data. A cid is a string, which must * contain enough information to uniquely identify the data. For example, if * your data contains translated strings, then your cid value must include the * interface text language selected for page. * - Call the get() method to attempt a cache read, to see if the cache already * contains your data. * - If your data is not already in the cache, compute it and add it to the * cache using the set() method. The third argument of set() can be used to * control the lifetime of your cache item. * * Example: * @code * $cid = 'mymodule_example:' . \Drupal::languageManager()->getCurrentLanguage()->getId(); * * $data = NULL; * if ($cache = \Drupal::cache()->get($cid)) { * $data = $cache->data; * } * else { * $data = my_module_complicated_calculation(); * \Drupal::cache()->set($cid, $data); * } * @endcode * * Note the use of $data and $cache->data in the above example. Calls to * \Drupal::cache()->get() return a record that contains the information stored * by \Drupal::cache()->set() in the data property as well as additional meta * information about the cached data. In order to make use of the cached data * you can access it via $cache->data. * * @section bins Cache bins * * Cache storage is separated into "bins", each containing various cache items. * Each bin can be configured separately; see @ref configuration. * * When you request a cache object, you can specify the bin name in your call to * \Drupal::cache(). Alternatively, you can request a bin by getting service * "cache.nameofbin" from the container. The default bin is called "default", with * service name "cache.default", it is used to store common and frequently used * caches. * * Other common cache bins are the following: * - bootstrap: Data needed from the beginning to the end of most requests, * that has a very strict limit on variations and is invalidated rarely. * - render: Contains cached HTML strings like cached pages and blocks, can * grow to large size. * - data: Contains data that can vary by path or similar context. * - discovery: Contains cached discovery data for things such as plugins, * views_data, or YAML discovered data such as library info. * * A module can define a cache bin by defining a service in its * modulename.services.yml file as follows (substituting the desired name for * "nameofbin"): * @code * cache.nameofbin: * class: Drupal\Core\Cache\CacheBackendInterface * tags: * - { name: cache.bin } * factory: cache_factory:get * arguments: [nameofbin] * @endcode * See the @link container Services topic @endlink for more on defining * services. * * @section delete Deletion * * There are two ways to remove an item from the cache: * - Deletion (using delete(), deleteMultiple() or deleteAll()) permanently * removes the item from the cache. * - Invalidation (using invalidate(), invalidateMultiple() or invalidateAll()) * is a "soft" delete that only marks items as "invalid", meaning "not fresh" * or "not fresh enough". Invalid items are not usually returned from the * cache, so in most ways they behave as if they have been deleted. However, * it is possible to retrieve invalid items, if they have not yet been * permanently removed by the garbage collector, by passing TRUE as the second * argument for get($cid, $allow_invalid). * * Use deletion if a cache item is no longer useful; for instance, if the item * contains references to data that has been deleted. Use invalidation if the * cached item may still be useful to some callers until it has been updated * with fresh data. The fact that it was fresh a short while ago may often be * sufficient. * * Invalidation is particularly useful to protect against stampedes. Rather than * having multiple concurrent requests updating the same cache item when it * expires or is deleted, there can be one request updating the cache, while the * other requests can proceed using the stale value. As soon as the cache item * has been updated, all future requests will use the updated value. * * @section tags Cache Tags * * The fourth argument of the set() method can be used to specify cache tags, * which are used to identify which data is included in each cache item. A cache * item can have multiple cache tags (an array of cache tags), and each cache * tag is a string. The convention is to generate cache tags of the form * [prefix]:[suffix]. Usually, you'll want to associate the cache tags of * entities, or entity listings. You won't have to manually construct cache tags * for them — just get their cache tags via * \Drupal\Core\Cache\CacheableDependencyInterface::getCacheTags() and * \Drupal\Core\Entity\EntityTypeInterface::getListCacheTags(). * Data that has been tagged can be invalidated as a group: no matter the Cache * ID (cid) of the cache item, no matter in which cache bin a cache item lives; * as long as it is tagged with a certain cache tag, it will be invalidated. * * Because of that, cache tags are a solution to the cache invalidation problem: * - For caching to be effective, each cache item must only be invalidated when * absolutely necessary. (i.e. maximizing the cache hit ratio.) * - For caching to be correct, each cache item that depends on a certain thing * must be invalidated whenever that certain thing is modified. * * A typical scenario: a user has modified a node that appears in two views, * three blocks and on twelve pages. Without cache tags, we couldn't possibly * know which cache items to invalidate, so we'd have to invalidate everything: * we had to sacrifice effectiveness to achieve correctness. With cache tags, we * can have both. * * Example: * @code * // A cache item with nodes, users, and some custom module data. * $tags = array( * 'my_custom_tag', * 'node:1', * 'node:3', * 'user:7', * ); * \Drupal::cache()->set($cid, $data, CacheBackendInterface::CACHE_PERMANENT, $tags); * * // Invalidate all cache items with certain tags. * \Drupal\Core\Cache\Cache::invalidateTags(array('user:1')); * @endcode * * Drupal is a content management system, so naturally you want changes to your * content to be reflected everywhere, immediately. That's why we made sure that * every entity type in Drupal 8 automatically has support for cache tags: when * you save an entity, you can be sure that the cache items that have the * corresponding cache tags will be invalidated. * This also is the case when you define your own entity types: you'll get the * exact same cache tag invalidation as any of the built-in entity types, with * the ability to override any of the default behavior if needed. * See \Drupal\Core\Cache\CacheableDepenencyInterface::getCacheTags(), * \Drupal\Core\Entity\EntityTypeInterface::getListCacheTags(), * \Drupal\Core\Entity\Entity::invalidateTagsOnSave() and * \Drupal\Core\Entity\Entity::invalidateTagsOnDelete(). * * @section context Cache contexts * * Some computed data depends on contextual data, such as the user roles of the * logged-in user who is viewing a page, the language the page is being rendered * in, the theme being used, etc. When caching the output of such a calculation, * you must cache each variation separately, along with information about which * variation of the contextual data was used in the calculatation. The next time * the computed data is needed, if the context matches that for an existing * cached data set, the cached data can be reused; if no context matches, a new * data set can be calculated and cached for later use. * * Cache contexts are services tagged with 'cache.context', whose classes * implement \Drupal\Core\Cache\Context\CacheContextInterface. See * https://www.drupal.org/developing/api/8/cache/contexts for more information * on cache contexts, including a list of the contexts that exist in Drupal * core, and information on how to define your own contexts. See the * @link container Services and the Dependency Injection Container @endlink * topic for more information about services. * * Typically, the cache context is specified as part of the #cache property * of a render array; see the Caching section of the * @link theme_render Render API overview topic @endlink for details. * * @section configuration Configuration * * By default cached data is stored in the database. This can be configured * though so that all cached data, or that of an individual cache bin, uses a * different cache backend, such as APCu or Memcache, for storage. * * In a settings.php file, you can override the service used for a particular * cache bin. For example, if your service implementation of * \Drupal\Core\Cache\CacheBackendInterface was called cache.custom, the * following line would make Drupal use it for the 'cache_render' bin: * @code * $settings['cache']['bins']['render'] = 'cache.custom'; * @endcode * * Additionally, you can register your cache implementation to be used by * default for all cache bins with: * @code * $settings['cache']['default'] = 'cache.custom'; * @endcode * * For cache bins that are stored in the database, the number of rows is limited * to 5000 by default. This can be changed for all database cache bins. For * example, to instead limit the number of rows to 50000: * @code * $settings['database_cache_max_rows']['default'] = 50000; * @endcode * * Or per bin (in this example we allow infinite entries): * @code * $settings['database_cache_max_rows']['bins']['dynamic_page_cache'] = -1; * @endcode * * For monitoring reasons it might be useful to figure out the amount of data * stored in tables. The following SQL snippet can be used for that: * @code * SELECT table_name AS `Table`, table_rows AS 'Num. of Rows', * ROUND(((data_length + index_length) / 1024 / 1024), 2) `Size in MB` FROM * information_schema.TABLES WHERE table_schema = '***DATABASE_NAME***' AND * table_name LIKE 'cache_%' ORDER BY (data_length + index_length) DESC * LIMIT 10; * @endcode * * @see \Drupal\Core\Cache\DatabaseBackend * * Finally, you can chain multiple cache backends together, see * \Drupal\Core\Cache\ChainedFastBackend and \Drupal\Core\Cache\BackendChain. * * @see https://www.drupal.org/node/1884796 * @} */ /** * @defgroup user_api User accounts, permissions, and roles * @{ * API for user accounts, access checking, roles, and permissions. * * @section sec_overview Overview and terminology * Drupal's permission system is based on the concepts of accounts, roles, * and permissions. * * Users (site visitors) have accounts, which include a user name, an email * address, a password (or some other means of authentication), and possibly * other fields (if defined on the site). Anonymous users have an implicit * account that does not have a real user name or any account information. * * Each user account is assigned one or more roles. The anonymous user account * automatically has the anonymous user role; real user accounts * automatically have the authenticated user role, plus any roles defined on * the site that they have been assigned. * * Each role, including the special anonymous and authenticated user roles, is * granted one or more named permissions, which allow them to perform certain * tasks or view certain content on the site. It is possible to designate a * role to be the "administrator" role; if this is set up, this role is * automatically granted all available permissions whenever a module is * enabled that defines permissions. * * All code in Drupal that allows users to perform tasks or view content must * check that the current user has the correct permission before allowing the * action. In the standard case, access checking consists of answering the * question "Does the current user have permission 'foo'?", and allowing or * denying access based on the answer. Note that access checking should nearly * always be done at the permission level, not by checking for a particular role * or user ID, so that site administrators can set up user accounts and roles * appropriately for their particular sites. * * @section sec_define Defining permissions * Modules define permissions via a $module.permissions.yml file. See * \Drupal\user\PermissionHandler for documentation of permissions.yml files. * * @section sec_access Access permission checking * Depending on the situation, there are several methods for ensuring that * access checks are done properly in Drupal: * - Routes: When you register a route, include a 'requirements' section that * either gives the machine name of the permission that is needed to visit the * URL of the route, or tells Drupal to use an access check method or service * to check access. See the @link menu Routing topic @endlink for more * information. * - Entities: Access for various entity operations is designated either with * simple permissions or access control handler classes in the entity * annotation. See the @link entity_api Entity API topic @endlink for more * information. * - Other code: There is a 'current_user' service, which can be injected into * classes to provide access to the current user account (see the * @link container Services and Dependency Injection topic @endlink for more * information on dependency injection). In code that cannot use dependency * injection, you can access this service and retrieve the current user * account object by calling \Drupal::currentUser(). Once you have a user * object for the current user (implementing \Drupal\user\UserInterface), you * can call inherited method * \Drupal\Core\Session\AccountInterface::hasPermission() to check * permissions, or pass this object into other functions/methods. * - Forms: Each element of a form array can have a Boolean '#access' property, * which determines whether that element is visible and/or usable. This is a * common need in forms, so the current user service (described above) is * injected into the form base class as method * \Drupal\Core\Form\FormBase::currentUser(). * * @section sec_entities User and role objects * User objects in Drupal are entity items, implementing * \Drupal\user\UserInterface. Role objects in Drupal are also entity items, * implementing \Drupal\user\RoleInterface. See the * @link entity_api Entity API topic @endlink for more information about * entities in general (including how to load, create, modify, and query them). * * Roles often need to be manipulated in automated test code, such as to add * permissions to them. Here's an example: * @code * $role = \Drupal\user\Entity\Role::load('authenticated'); * $role->grantPermission('access comments'); * $role->save(); * @endcode * * Other important interfaces: * - \Drupal\Core\Session\AccountInterface: The part of UserInterface that * deals with access checking. In writing code that checks access, your * method parameters should use this interface, not UserInterface. * - \Drupal\Core\Session\AccountProxyInterface: The interface for the * current_user service (described above). * @} */ /** * @defgroup container Services and Dependency Injection Container * @{ * Overview of the Dependency Injection Container and Services. * * @section sec_overview Overview of container, injection, and services * The Services and Dependency Injection Container concepts have been adopted by * Drupal from the @link http://symfony.com/ Symfony framework. @endlink A * "service" (such as accessing the database, sending email, or translating user * interface text) is defined (given a name and an interface or at least a * class that defines the methods that may be called), and a default class is * designated to provide the service. These two steps must be done together, and * can be done by Drupal Core or a module. Other modules can then define * alternative classes to provide the same services, overriding the default * classes. Classes and functions that need to use the service should always * instantiate the class via the dependency injection container (also known * simply as the "container"), rather than instantiating a particular service * provider class directly, so that they get the correct class (default or * overridden). * * See https://www.drupal.org/node/2133171 for more detailed information on * services and the dependency injection container. * * @section sec_discover Discovering existing services * Drupal core defines many core services in the core.services.yml file (in the * top-level core directory). Some Drupal Core modules and contributed modules * also define services in modulename.services.yml files. API reference sites * (such as https://api.drupal.org) generate lists of all existing services from * these files. Look for the Services link in the API Navigation block. * Alternatively you can look through the individual files manually. * * A typical service definition in a *.services.yml file looks like this: * @code * path.alias_manager: * class: Drupal\Core\Path\AliasManager * arguments: ['@path.crud', '@path.alias_whitelist', '@language_manager'] * @endcode * Some services use other services as factories; a typical service definition * is: * @code * cache.entity: * class: Drupal\Core\Cache\CacheBackendInterface * tags: * - { name: cache.bin } * factory: cache_factory:get * arguments: [entity] * @endcode * * The first line of a service definition gives the unique machine name of the * service. This is often prefixed by the module name if provided by a module; * however, by convention some service names are prefixed by a group name * instead, such as cache.* for cache bins and plugin.manager.* for plugin * managers. * * The class line either gives the default class that provides the service, or * if the service uses a factory class, the interface for the service. If the * class depends on other services, the arguments line lists the machine * names of the dependencies (preceded by '@'); objects for each of these * services are instantiated from the container and passed to the class * constructor when the service class is instantiated. Other arguments can also * be passed in; see the section at https://www.drupal.org/node/2133171 for more * detailed information. * * Services using factories can be defined as shown in the above example, if the * factory is itself a service. The factory can also be a class; details of how * to use service factories can be found in the section at * https://www.drupal.org/node/2133171. * * @section sec_container Accessing a service through the container * As noted above, if you need to use a service in your code, you should always * instantiate the service class via a call to the container, using the machine * name of the service, so that the default class can be overridden. There are * several ways to make sure this happens: * - For service-providing classes, see other sections of this documentation * describing how to pass services as arguments to the constructor. * - Plugin classes, controllers, and similar classes have create() or * createInstance() methods that are used to create an instance of the class. * These methods come from different interfaces, and have different * arguments, but they all include an argument $container of type * \Symfony\Component\DependencyInjection\ContainerInterface. * If you are defining one of these classes, in the create() or * createInstance() method, call $container->get('myservice.name') to * instantiate a service. The results of these calls are generally passed to * the class constructor and saved as member variables in the class. * - For functions and class methods that do not have access to either of * the above methods of dependency injection, you can use service location to * access services, via a call to the global \Drupal class. This class has * special methods for accessing commonly-used services, or you can call a * generic method to access any service. Examples: * @code * // Retrieve the entity.manager service object (special method exists). * $manager = \Drupal::entityManager(); * // Retrieve the service object for machine name 'foo.bar'. * $foobar = \Drupal::service('foo.bar'); * @endcode * * As a note, you should always use dependency injection (via service arguments * or create()/createInstance() methods) if possible to instantiate services, * rather than service location (via the \Drupal class), because: * - Dependency injection facilitates writing unit tests, since the container * argument can be mocked and the create() method can be bypassed by using * the class constructor. If you use the \Drupal class, unit tests are much * harder to write and your code has more dependencies. * - Having the service interfaces on the class constructor and member variables * is useful for IDE auto-complete and self-documentation. * * @section sec_define Defining a service * If your module needs to define a new service, here are the steps: * - Choose a unique machine name for your service. Typically, this should * start with your module name. Example: mymodule.myservice. * - Create a PHP interface to define what your service does. * - Create a default class implementing your interface that provides your * service. If your class needs to use existing services (such as database * access), be sure to make these services arguments to your class * constructor, and save them in member variables. Also, if the needed * services are provided by other modules and not Drupal Core, you'll want * these modules to be dependencies of your module. * - Add an entry to a modulename.services.yml file for the service. See * @ref sec_discover above, or existing *.services.yml files in Core, for the * syntax; it will start with your machine name, refer to your default class, * and list the services that need to be passed into your constructor. * * Services can also be defined dynamically, as in the * \Drupal\Core\CoreServiceProvider class, but this is less common for modules. * * @section sec_tags Service tags * Some services have tags, which are defined in the service definition. See * @link service_tag Service Tags @endlink for usage. * * @section sec_injection Overriding the default service class * Modules can override the default classes used for services. Here are the * steps: * - Define a class in the top-level namespace for your module * (Drupal\my_module), whose name is the camel-case version of your module's * machine name followed by "ServiceProvider" (for example, if your module * machine name is my_module, the class must be named * MyModuleServiceProvider). * - The class needs to implement * \Drupal\Core\DependencyInjection\ServiceModifierInterface, which is * typically done by extending * \Drupal\Core\DependencyInjection\ServiceProviderBase. * - The class needs to contain one method: alter(). This method does the * actual work of telling Drupal to use your class instead of the default. * Here's an example: * @code * public function alter(ContainerBuilder $container) { * // Override the language_manager class with a new class. * $definition = $container->getDefinition('language_manager'); * $definition->setClass('Drupal\my_module\MyLanguageManager'); * } * @endcode * Note that $container here is an instance of * \Drupal\Core\DependencyInjection\ContainerBuilder. * * @see https://www.drupal.org/node/2133171 * @see core.services.yml * @see \Drupal * @see \Symfony\Component\DependencyInjection\ContainerInterface * @see plugin_api * @see menu * @} */ /** * @defgroup listing_page_service Page header for Services page * @{ * Introduction to services * * A "service" (such as accessing the database, sending email, or translating * user interface text) can be defined by a module or Drupal core. Defining a * service means giving it a name and designating a default class to provide the * service; ideally, there should also be an interface that defines the methods * that may be called. Services are collected into the Dependency Injection * Container, and can be overridden to use different classes or different * instantiation by modules. See the * @link container Services and Dependency Injection Container topic @endlink * for details. * * Some services have tags, which are defined in the service definition. Tags * are used to define a group of related services, or to specify some aspect of * how the service behaves. See the * @link service_tag Service Tags topic @endlink for more information. * * @see container * @see service_tag * * @} */ /** * @defgroup typed_data Typed Data API * @{ * API for describing data based on a set of available data types. * * PHP has data types, such as int, string, float, array, etc., and it is an * object-oriented language that lets you define classes and interfaces. * However, in some cases, it is useful to be able to define an abstract * type (as in an interface, free of implementation details), that still has * properties (which an interface cannot) as well as meta-data. The Typed Data * API provides this abstraction. * * @section sec_overview Overview * Each data type in the Typed Data API is a plugin class (annotation class * example: \Drupal\Core\TypedData\Annotation\DataType); these plugins are * managed by the typed_data_manager service (by default * \Drupal\Core\TypedData\TypedDataManager). Each data object encapsulates a * single piece of data, provides access to the metadata, and provides * validation capability. Also, the typed data plugins have a shorthand * for easily accessing data values, described in @ref sec_tree. * * The metadata of a data object is defined by an object based on a class called * the definition class (see \Drupal\Core\TypedData\DataDefinitionInterface). * The class used can vary by data type and can be specified in the data type's * plugin definition, while the default is set in the $definition_class property * of the annotation class. The default class is * \Drupal\Core\TypedData\DataDefinition. For data types provided by a plugin * deriver, the plugin deriver can set the definition_class property too. * The metadata object provides information about the data, such as the data * type, whether it is translatable, the names of its properties (for complex * types), and who can access it. * * See https://www.drupal.org/node/1794140 for more information about the Typed * Data API. * * @section sec_varieties Varieties of typed data * There are three kinds of typed data: primitive, complex, and list. * * @subsection sub_primitive Primitive data types * Primitive data types wrap PHP data types and also serve as building blocks * for complex and list typed data. Each primitive data type has an interface * that extends \Drupal\Core\TypedData\PrimitiveInterface, with getValue() * and setValue() methods for accessing the data value, and a default plugin * implementation. Here's a list: * - \Drupal\Core\TypedData\Type\IntegerInterface: Plugin ID integer, * corresponds to PHP type int. * - \Drupal\Core\TypedData\Type\StringInterface: Plugin ID string, * corresponds to PHP type string. * - \Drupal\Core\TypedData\Type\FloatInterface: Plugin ID float, * corresponds to PHP type float. * - \Drupal\Core\TypedData\Type\BooleanInterface: Plugin ID bool, * corresponds to PHP type bool. * - \Drupal\Core\TypedData\Type\BinaryInterface: Plugin ID binary, * corresponds to a PHP file resource. * - \Drupal\Core\TypedData\Type\UriInterface: Plugin ID uri. * * @subsection sec_complex Complex data * Complex data types, with interface * \Drupal\Core\TypedData\ComplexDataInterface, represent data with named * properties; the properties can be accessed with get() and set() methods. * The value of each property is itself a typed data object, which can be * primitive, complex, or list data. * * The base type for most complex data is the * \Drupal\Core\TypedData\Plugin\DataType\Map class, which represents an * associative array. Map provides its own definition class in the annotation, * \Drupal\Core\TypedData\MapDataDefinition, and most complex data classes * extend this class. The getValue() and setValue() methods on the Map class * enforce the data definition and its property structure. * * The Drupal Field API uses complex typed data for its field items, with * definition class \Drupal\Core\Field\TypedData\FieldItemDataDefinition. * * @section sec_list Lists * List data types, with interface \Drupal\Core\TypedData\ListInterface, * represent data that is an ordered list of typed data, all of the same type. * More precisely, the plugins in the list must have the same base plugin ID; * however, some types (for example field items and entities) are provided by * plugin derivatives and the sub IDs can be different. * * @section sec_tree Tree handling * Typed data allows you to use shorthand to get data values nested in the * implicit tree structure of the data. For example, to get the value from * an entity field item, the Entity Field API allows you to call: * @code * $value = $entity->fieldName->propertyName; * @endcode * This is really shorthand for: * @code * $field_item_list = $entity->get('fieldName'); * $field_item = $field_item_list->get(0); * $property = $field_item->get('propertyName'); * $value = $property->getValue(); * @endcode * Some notes: * - $property, $field_item, and $field_item_list are all typed data objects, * while $value is a raw PHP value. * - You can call $property->getParent() to get $field_item, * $field_item->getParent() to get $field_item_list, or * $field_item_list->getParent() to get $typed_entity ($entity wrapped in a * typed data object). $typed_entity->getParent() is NULL. * - For all of these ->getRoot() returns $typed_entity. * - The langcode property is on $field_item_list, but you can access it * on $property as well, so that all items will report the same langcode. * - When the value of $property is changed by calling $property->setValue(), * $property->onChange() will fire, which in turn calls the parent object's * onChange() method and so on. This allows parent objects to react upon * changes of contained properties or list items. * * @section sec_defining Defining data types * To define a new data type: * - Create a class that implements one of the Typed Data interfaces. * Typically, you will want to extend one of the classes listed in the * sections above as a starting point. * - Make your class into a DataType plugin. To do that, put it in namespace * \Drupal\yourmodule\Plugin\DataType (where "yourmodule" is your module's * short name), and add annotation of type * \Drupal\Core\TypedData\Annotation\DataType to the documentation header. * See the @link plugin_api Plugin API topic @endlink and the * @link annotation Annotations topic @endlink for more information. * * @section sec_using Using data types * The data types of the Typed Data API can be used in several ways, once they * have been defined: * - In the Field API, data types can be used as the class in the property * definition of the field. See the @link field Field API topic @endlink for * more information. * - In configuration schema files, you can use the unique ID ('id' annotation) * from any DataType plugin class as the 'type' value for an entry. See the * @link config_api Confuration API topic @endlink for more information. * - If you need to create a typed data object in code, first get the * typed_data_manager service from the container or by calling * \Drupal::typedDataManager(). Then pass the plugin ID to * $manager::createDataDefinition() to create an appropriate data definition * object. Then pass the data definition object and the value of the data to * $manager::create() to create a typed data object. * * @see plugin_api * @see container * @} */ /** * @defgroup testing Automated tests * @{ * Overview of PHPUnit tests and Simpletest tests. * * The Drupal project has embraced a philosophy of using automated tests, * consisting of both unit tests (which test the functionality of classes at a * low level) and functional tests (which test the functionality of Drupal * systems at a higher level, usually involving web output). The goal is to * have test coverage for all or most of the components and features, and to * run the automated tests before any code is changed or added, to make sure * it doesn't break any existing functionality (regression testing). * * In order to implement this philosophy, developers need to do the following: * - When making a patch to fix a bug, make sure that the bug fix patch includes * a test that fails without the code change and passes with the code change. * This helps reviewers understand what the bug is, demonstrates that the code * actually fixes the bug, and ensures the bug will not reappear due to later * code changes. * - When making a patch to implement a new feature, include new unit and/or * functional tests in the patch. This serves to both demonstrate that the * code actually works, and ensure that later changes do not break the new * functionality. * * @section write_unit Writing PHPUnit tests for classes * PHPUnit tests for classes are written using the industry-standard PHPUnit * framework. Use a PHPUnit test to test functionality of a class if the Drupal * environment (database, settings, etc.) and web browser are not needed for the * test, or if the Drupal environment can be replaced by a "mock" object. To * write a PHPUnit test: * - Define a class that extends \Drupal\Tests\UnitTestCase. * - The class name needs to end in the word Test. * - The namespace must be a subspace/subdirectory of \Drupal\yourmodule\Tests, * where yourmodule is your module's machine name. * - The test class file must be named and placed under the * yourmodule/tests/src/Unit directory, according to the PSR-4 standard. * - Your test class needs a phpDoc comment block with a description and * a @group annotation, which gives information about the test. * - Add test cases by adding method names that start with 'test' and have no * arguments, for example testYourTestCase(). Each one should test a logical * subset of the functionality. * For more details, see: * - https://www.drupal.org/phpunit for full documentation on how to write * PHPUnit tests for Drupal. * - http://phpunit.de for general information on the PHPUnit framework. * - @link oo_conventions Object-oriented programming topic @endlink for more * on PSR-4, namespaces, and where to place classes. * * @section write_functional Writing functional tests * Functional tests are written using a Drupal-specific framework that is, for * historical reasons, known as "Simpletest". Use a Simpletest test to test the * functionality of sub-system of Drupal, if the functionality depends on the * Drupal database and settings, or to test the web output of Drupal. To * write a Simpletest test: * - For functional tests of the web output of Drupal, define a class that * extends \Drupal\simpletest\WebTestBase, which contains an internal web * browser and defines many helpful test assertion methods that you can use * in your tests. You can specify modules to be enabled by defining a * $modules member variable -- keep in mind that by default, WebTestBase uses * a "testing" install profile, with a minimal set of modules enabled. * - For functional tests that do not test web output, define a class that * extends \Drupal\KernelTests\KernelTestBase. This class is much faster * than WebTestBase, because instead of making a full install of Drupal, it * uses an in-memory pseudo-installation (similar to what the installer and * update scripts use). To use this test class, you will need to create the * database tables you need and install needed modules manually. * - The namespace must be a subspace/subdirectory of \Drupal\yourmodule\Tests, * where yourmodule is your module's machine name. * - The test class file must be named and placed under the yourmodule/src/Tests * directory, according to the PSR-4 standard. * - Your test class needs a phpDoc comment block with a description and * a @group annotation, which gives information about the test. * - You may also override the default setUp() method, which can set be used to * set up content types and similar procedures. * - In some cases, you may need to write a test module to support your test; * put such modules under the yourmodule/tests/modules directory. * - Add test cases by adding method names that start with 'test' and have no * arguments, for example testYourTestCase(). Each one should test a logical * subset of the functionality. Each method runs in a new, isolated test * environment, so it can only rely on the setUp() method, not what has * been set up by other test methods. * For more details, see: * - https://www.drupal.org/simpletest for full documentation on how to write * functional tests for Drupal. * - @link oo_conventions Object-oriented programming topic @endlink for more * on PSR-4, namespaces, and where to place classes. * * @section write_functional_phpunit Write functional PHP tests (phpunit) * Functional tests extend the BrowserTestBase base class, and use PHPUnit as * their underlying framework. They use a simulated browser, in which the test * can click links, visit URLs, post to forms, etc. To write a functional test: * - Extend \Drupal\Tests\BrowserTestBase. * - Place the test in the yourmodule/tests/src/Functional/ directory and use * the \Drupal\Tests\yourmodule\Functional namespace. * - Add a @group annotation. For example, if the test is for a Drupal 6 * migration process, the group core uses is migrate_drupal_6. Use yourmodule * as the group name if the test does not belong to another larger group. * - You may also override the default setUp() method, which can be used to set * up content types and similar procedures. Don't forget to call the parent * method. * - In some cases, you may need to write a test module to support your test; * put such modules under the yourmodule/tests/modules directory. * - Add test cases by adding method names that start with 'test' and have no * arguments, for example testYourTestCase(). Each one should test a logical * subset of the functionality. Each method runs in a new, isolated test * environment, so it can only rely on the setUp() method, not what has * been set up by other test methods. * For more details, see: * - https://www.drupal.org/docs/8/phpunit/phpunit-browser-test-tutorial for * a full tutorial on how to write functional PHPUnit tests for Drupal. * - https://www.drupal.org/phpunit for the full documentation on how to write * PHPUnit tests for Drupal. * * @section write_jsfunctional_phpunit Write functional JavaScript tests (phpunit) * To write a functional test that relies on JavaScript: * - Extend \Drupal\FunctionalJavaScriptTests\JavascriptTestBase. * - Place the test into the yourmodule/tests/src/FunctionalJavascript/ * directory and use the \Drupal\Tests\yourmodule\FunctionalJavascript * namespace. * - Add a @group annotation. Use yourmodule as the group name if the test does * not belong to another larger group. * - Set up PhantomJS; see http://phantomjs.org/download.html. * - To run tests, see core/tests/README.md. * - When clicking a link/button with Ajax behavior attached, keep in mind that * the underlying browser might take time to deliver changes to the HTML. Use * $this->assertSession()->assertWaitOnAjaxRequest() to wait for the Ajax * request to finish. * For more details, see: * - https://www.drupal.org/docs/8/phpunit/phpunit-javascript-testing-tutorial * for a full tutorial on how to write PHPUnit JavaScript tests for Drupal. * - https://www.drupal.org/phpunit for the full documentation on how to write * PHPUnit tests for Drupal. * * @section running Running tests * You can run both Simpletest and PHPUnit tests by enabling the core Testing * module (core/modules/simpletest). Once that module is enabled, tests can be * run using the core/scripts/run-tests.sh script, using * @link https://www.drupal.org/project/drush Drush @endlink, or from the * Testing module user interface. * * PHPUnit tests can also be run from the command line, using the PHPUnit * framework. See https://www.drupal.org/node/2116263 for more information. * @} */ /** * @defgroup php_assert PHP Runtime Assert Statements * @{ * Use of the assert() statement in Drupal. * * Unit tests also use the term "assertion" to refer to test conditions, so to * avoid confusion the term "runtime assertion" will be used for the assert() * statement throughout the documentation. * * A runtime assertion is a statement that is expected to always be true at * the point in the code it appears at. They are tested using PHP's internal * @link http://php.net/assert assert() @endlink statement. If an * assertion is ever FALSE it indicates an error in the code or in module or * theme configuration files. User-provided configuration files should be * verified with standard control structures at all times, not just checked in * development environments with assert() statements on. * * The Drupal project primarily uses runtime assertions to enforce the * expectations of the API by failing when incorrect calls are made by code * under development. While PHP type hinting does this for objects and arrays, * runtime assertions do this for scalars (strings, integers, floats, etc.) and * complex data structures such as cache and render arrays. They ensure that * methods' return values are the documented datatypes. They also verify that * objects have been properly configured and set up by the service container. * They supplement unit tests by checking scenarios that do not have unit tests * written for them. * * There are two php settings which affect runtime assertions. The first, * assert.exception, should always be set to 1. The second is zend.assertions. * Set this to -1 in production and 1 in development. * * See https://www.drupal.org/node/2492225 for more information on runtime * assertions. * @} */ /** * @defgroup info_types Information types * @{ * Types of information in Drupal. * * Drupal has several distinct types of information, each with its own methods * for storage and retrieval: * - Content: Information meant to be displayed on your site: articles, basic * pages, images, files, custom blocks, etc. Content is stored and accessed * using @link entity_api Entities @endlink. * - Session: Information about individual users' interactions with the site, * such as whether they are logged in. This is really "state" information, but * it is not stored the same way so it's a separate type here. Session * information is available from the Request object. The session implements * \Symfony\Component\HttpFoundation\Session\SessionInterface. * - State: Information of a temporary nature, generally machine-generated and * not human-edited, about the current state of your site. Examples: the time * when Cron was last run, whether node access permissions need rebuilding, * etc. See @link state_api the State API topic @endlink for more information. * - Configuration: Information about your site that is generally (or at least * can be) human-edited, but is not Content, and is meant to be relatively * permanent. Examples: the name of your site, the content types and views * you have defined, etc. See * @link config_api the Configuration API topic @endlink for more information. * * @see cache * @see i18n * @} */ /** * @defgroup extending Extending and altering Drupal * @{ * Overview of extensions and alteration methods for Drupal. * * @section sec_types Types of extensions * Drupal's core behavior can be extended and altered via these three basic * types of extensions: * - Themes: Themes alter the appearance of Drupal sites. They can include * template files, which alter the HTML markup and other raw output of the * site; CSS files, which alter the styling applied to the HTML; and * JavaScript, Flash, images, and other files. For more information, see the * @link theme_render Theme system and render API topic @endlink and * https://www.drupal.org/docs/8/theming * - Modules: Modules add to or alter the behavior and functionality of Drupal, * by using one or more of the methods listed below. For more information * about creating modules, see https://www.drupal.org/developing/modules/8 * - Installation profiles: Installation profiles can be used to * create distributions, which are complete specific-purpose packages of * Drupal including additional modules, themes, and data. For more * information, see https://www.drupal.org/developing/distributions. * * @section sec_alter Alteration methods for modules * Here is a list of the ways that modules can alter or extend Drupal's core * behavior, or the behavior of other modules: * - Hooks: Specially-named functions that a module defines, which are * discovered and called at specific times, usually to alter behavior or data. * See the @link hooks Hooks topic @endlink for more information. * - Plugins: Classes that a module defines, which are discovered and * instantiated at specific times to add functionality. See the * @link plugin_api Plugin API topic @endlink for more information. * - Entities: Special plugins that define entity types for storing new types * of content or configuration in Drupal. See the * @link entity_api Entity API topic @endlink for more information. * - Services: Classes that perform basic operations within Drupal, such as * accessing the database and sending email. See the * @link container Dependency Injection Container and Services topic @endlink * for more information. * - Routing: Providing or altering "routes", which are URLs that Drupal * responds to, or altering routing behavior with event listener classes. * See the @link menu Routing and menu topic @endlink for more information. * - Events: Modules can register as event subscribers; when an event is * dispatched, a method is called on each registered subscriber, allowing each * one to react. See the @link events Events topic @endlink for more * information. * * @section sec_sample *.info.yml files * Extensions must each be located in a directory whose name matches the short * name (or machine name) of the extension, and this directory must contain a * file named machine_name.info.yml (where machine_name is the machine name of * the extension). See \Drupal\Core\Extension\InfoParserInterface::parse() for * documentation of the format of .info.yml files. * @} */ /** * @defgroup plugin_api Plugin API * @{ * Using the Plugin API * * @section sec_overview Overview and terminology * * The basic idea of plugins is to allow a particular module or subsystem of * Drupal to provide functionality in an extensible, object-oriented way. The * controlling module or subsystem defines the basic framework (interface) for * the functionality, and other modules can create plugins (implementing the * interface) with particular behaviors. The controlling module instantiates * existing plugins as needed, and calls methods to invoke their functionality. * Examples of functionality in Drupal Core that use plugins include: the block * system (block types are plugins), the entity/field system (entity types, * field types, field formatters, and field widgets are plugins), the image * manipulation system (image effects and image toolkits are plugins), and the * search system (search page types are plugins). * * Plugins are grouped into plugin types, each generally defined by an * interface. Each plugin type is managed by a plugin manager service, which * uses a plugin discovery method to discover provided plugins of that type and * instantiate them using a plugin factory. * * Some plugin types make use of the following concepts or components: * - Plugin derivatives: Allows a single plugin class to present itself as * multiple plugins. Example: the Menu module provides a block for each * defined menu via a block plugin derivative. * - Plugin mapping: Allows a plugin class to map a configuration string to an * instance, and have the plugin automatically instantiated without writing * additional code. * - Plugin collections: Provide a way to lazily instantiate a set of plugin * instances from a single plugin definition. * * There are several things a module developer may need to do with plugins: * - Define a completely new plugin type: see @ref sec_define below. * - Create a plugin of an existing plugin type: see @ref sec_create below. * - Perform tasks that involve plugins: see @ref sec_use below. * * See https://www.drupal.org/developing/api/8/plugins for more detailed * documentation on the plugin system. There are also topics for a few * of the many existing types of plugins: * - @link block_api Block API @endlink * - @link entity_api Entity API @endlink * - @link field Various types of field-related plugins @endlink * - @link views_plugins Views plugins @endlink (has links to topics covering * various specific types of Views plugins). * - @link search Search page plugins @endlink * * @section sec_define Defining a new plugin type * To define a new plugin type: * - Define an interface for the plugin. This describes the common set of * behavior, and the methods you will call on each plugin class that is * instantiated. Usually this interface will extend one or more of the * following interfaces: * - \Drupal\Component\Plugin\PluginInspectionInterface * - \Drupal\Component\Plugin\ConfigurablePluginInterface * - \Drupal\Component\Plugin\ContextAwarePluginInterface * - \Drupal\Core\Plugin\PluginFormInterface * - \Drupal\Core\Executable\ExecutableInterface * - (optional) Create a base class that provides a partial implementation of * the interface, for the convenience of developers wishing to create plugins * of your type. The base class usually extends * \Drupal\Core\Plugin\PluginBase, or one of the base classes that extends * this class. * - Choose a method for plugin discovery, and define classes as necessary. * See @ref sub_discovery below. * - Create a plugin manager/factory class and service, which will discover and * instantiate plugins. See @ref sub_manager below. * - Use the plugin manager to instantiate plugins. Call methods on your plugin * interface to perform the tasks of your plugin type. * - (optional) If appropriate, define a plugin collection. See @ref * sub_collection below for more information. * * @subsection sub_discovery Plugin discovery * Plugin discovery is the process your plugin manager uses to discover the * individual plugins of your type that have been defined by your module and * other modules. Plugin discovery methods are classes that implement * \Drupal\Component\Plugin\Discovery\DiscoveryInterface. Most plugin types use * one of the following discovery mechanisms: * - Annotation: Plugin classes are annotated and placed in a defined namespace * subdirectory. Most Drupal Core plugins use this method of discovery. * - Hook: Plugin modules need to implement a hook to tell the manager about * their plugins. * - YAML: Plugins are listed in YAML files. Drupal Core uses this method for * discovering local tasks and local actions. This is mainly useful if all * plugins use the same class, so it is kind of like a global derivative. * - Static: Plugin classes are registered within the plugin manager class * itself. Static discovery is only useful if modules cannot define new * plugins of this type (if the list of available plugins is static). * * It is also possible to define your own custom discovery mechanism or mix * methods together. And there are many more details, such as annotation * decorators, that apply to some of the discovery methods. See * https://www.drupal.org/developing/api/8/plugins for more details. * * The remainder of this documentation will assume Annotation-based discovery, * since this is the most common method. * * @subsection sub_manager Defining a plugin manager class and service * To define an annotation-based plugin manager: * - Choose a namespace subdirectory for your plugin. For example, search page * plugins go in directory Plugin/Search under the module namespace. * - Define an annotation class for your plugin type. This class should extend * \Drupal\Component\Annotation\Plugin, and for most plugin types, it should * contain member variables corresponding to the annotations plugins will * need to provide. All plugins have at least $id: a unique string * identifier. * - Define an alter hook for altering the discovered plugin definitions. You * should document the hook in a *.api.php file. * - Define a plugin manager class. This class should implement * \Drupal\Component\Plugin\PluginManagerInterface; most plugin managers do * this by extending \Drupal\Core\Plugin\DefaultPluginManager. If you do * extend the default plugin manager, the only method you will probably need * to define is the class constructor, which will need to call the parent * constructor to provide information about the annotation class and plugin * namespace for discovery, set up the alter hook, and possibly set up * caching. See classes that extend DefaultPluginManager for examples. * - Define a service for your plugin manager. See the * @link container Services topic for more information. @endlink Your service * definition should look something like this, referencing your manager * class and the parent (default) plugin manager service to inherit * constructor arguments: * @code * plugin.manager.mymodule: * class: Drupal\mymodule\MyPluginManager * parent: default_plugin_manager * @endcode * - If your plugin is configurable, you will also need to define the * configuration schema and possibly a configuration entity type. See the * @link config_api Configuration API topic @endlink for more information. * * @subsection sub_collection Defining a plugin collection * Some configurable plugin types allow administrators to create zero or more * instances of each plugin, each with its own configuration. For example, * a single block plugin can be configured several times, to display in * different regions of a theme, with different visibility settings, a * different title, or other plugin-specific settings. To make this possible, * a plugin type can make use of what's known as a plugin collection. * * A plugin collection is a class that extends * \Drupal\Component\Plugin\LazyPluginCollection or one of its subclasses; there * are several examples in Drupal Core. If your plugin type uses a plugin * collection, it will usually also have a configuration entity, and the entity * class should implement * \Drupal\Core\Entity\EntityWithPluginCollectionInterface. Again, there are * several examples in Drupal Core; see also the @link config_api Configuration * API topic @endlink for more information about configuration entities. * * @section sec_create Creating a plugin of an existing type * Assuming the plugin type uses annotation-based discovery, in order to create * a plugin of an existing type, you will be creating a class. This class must: * - Implement the plugin interface, so that it has the required methods * defined. Usually, you'll want to extend the plugin base class, if one has * been provided. * - Have the right annotation in its documentation header. See the * @link annotation Annotation topic @endlink for more information about * annotation. * - Be in the right plugin namespace, in order to be discovered. * Often, the easiest way to make sure this happens is to find an existing * example of a working plugin class of the desired type, and copy it into your * module as a starting point. * * You can also create a plugin derivative, which allows your plugin class * to present itself to the user interface as multiple plugins. To do this, * in addition to the plugin class, you'll need to create a separate plugin * derivative class implementing * \Drupal\Component\Plugin\Derivative\DerivativeInterface. The classes * \Drupal\system\Plugin\Block\SystemMenuBlock (plugin class) and * \Drupal\system\Plugin\Derivative\SystemMenuBlock (derivative class) are a * good example to look at. * * @section sec_use Performing tasks involving plugins * Here are the steps to follow to perform a task that involves plugins: * - Locate the machine name of the plugin manager service, and instantiate the * service. See the @link container Services topic @endlink for more * information on how to do this. * - On the plugin manager class, use methods like getDefinition(), * getDefinitions(), or other methods specific to particular plugin managers * to retrieve information about either specific plugins or the entire list of * defined plugins. * - Call the createInstance() method on the plugin manager to instantiate * individual plugin objects. * - Call methods on the plugin objects to perform the desired tasks. * * @see annotation * @} */ /** * @defgroup oo_conventions Objected-oriented programming conventions * @{ * PSR-4, namespaces, class naming, and other conventions. * * A lot of the PHP code in Drupal is object oriented (OO), making use of * @link http://php.net/manual/language.oop5.php PHP classes, interfaces, and traits @endlink * (which are loosely referred to as "classes" in the rest of this topic). The * following conventions and standards apply to this version of Drupal: * - Each class must be in its own file. * - Classes must be namespaced. If a module defines a class, the namespace * must start with \Drupal\module_name. If it is defined by Drupal Core for * use across many modules, the namespace should be \Drupal\Core or * \Drupal\Component, with the exception of the global class \Drupal. See * https://www.drupal.org/node/1353118 for more about namespaces. * - In order for the PSR-4-based class auto-loader to find the class, it must * be located in a directory corresponding to the namespace. For * module-defined classes, if the namespace is \Drupal\module_name\foo\bar, * then the class goes under the main module directory in directory * src/foo/bar. For Drupal-wide classes, if the namespace is * \Drupal\Core\foo\bar, then it goes in directory * core/lib/Drupal/Core/foo/bar. See https://www.drupal.org/node/2156625 for * more information about PSR-4. * - Some classes have annotations added to their documentation headers. See * the @link annotation Annotation topic @endlink for more information. * - Standard plugin discovery requires particular namespaces and annotation * for most plugin classes. See the * @link plugin_api Plugin API topic @endlink for more information. * - There are project-wide coding standards for OO code, including naming: * https://www.drupal.org/node/608152 * - Documentation standards for classes are covered on: * https://www.drupal.org/coding-standards/docs#classes * @} */ /** * @defgroup listing_page_class Page header for Classes page * @{ * Introduction to classes * * A lot of the PHP code in Drupal is object oriented (OO), making use of * @link http://php.net/manual/language.oop5.php PHP classes, interfaces, and traits. @endlink * See the * @link oo_conventions Objected-oriented programming conventions @endlink * for more information. * * @see oo_conventions * * @} */ /** * @defgroup listing_page_namespace Page header for Namespaces page * @{ * Introduction to namespaces * * PHP classes, interfaces, and traits in Drupal are * @link http://php.net/manual/language.namespaces.rationale.php namespaced. @endlink * See the * @link oo_conventions Objected-oriented programming conventions @endlink * for more information. * * @see oo_conventions * * @} */ /** * @defgroup best_practices Best practices for developers * @{ * Overview of standards and best practices for developers * * Ideally, all code that is included in Drupal Core and contributed modules, * themes, and distributions will be secure, internationalized, maintainable, * and efficient. In order to facilitate this, the Drupal community has * developed a set of guidelines and standards for developers to follow. Most of * these standards can be found under * @link https://www.drupal.org/developing/best-practices Best practices on Drupal.org @endlink * * Standards and best practices that developers should be aware of include: * - Security: https://www.drupal.org/writing-secure-code and the * @link sanitization Sanitization functions topic @endlink * - Coding standards: https://www.drupal.org/coding-standards * and https://www.drupal.org/coding-standards/docs * - Accessibility: https://www.drupal.org/node/1637990 (modules) and * https://www.drupal.org/node/464472 (themes) * - Usability: https://www.drupal.org/ui-standards * - Internationalization: @link i18n Internationalization topic @endlink * - Automated testing: @link testing Automated tests topic @endlink * @} */ /** * @defgroup utility Utility classes and functions * @{ * Overview of utility classes and functions for developers. * * Drupal provides developers with a variety of utility functions that make it * easier and more efficient to perform tasks that are either really common, * tedious, or difficult. Utility functions help to reduce code duplication and * should be used in place of one-off code whenever possible. * * @see common.inc * @see file * @see format * @see php_wrappers * @see sanitization * @see transliteration * @see validation * @} */ /** * @defgroup hooks Hooks * @{ * Define functions that alter the behavior of Drupal core. * * One way for modules to alter the core behavior of Drupal (or another module) * is to use hooks. Hooks are specially-named functions that a module defines * (this is known as "implementing the hook"), which are discovered and called * at specific times to alter or add to the base behavior or data (this is * known as "invoking the hook"). Each hook has a name (example: * hook_batch_alter()), a defined set of parameters, and a defined return value. * Your modules can implement hooks that are defined by Drupal core or other * modules that they interact with. Your modules can also define their own * hooks, in order to let other modules interact with them. * * To implement a hook: * - Locate the documentation for the hook. Hooks are documented in *.api.php * files, by defining functions whose name starts with "hook_" (these * files and their functions are never loaded by Drupal -- they exist solely * for documentation). The function should have a documentation header, as * well as a sample function body. For example, in the core file * system.api.php, you can find hooks such as hook_batch_alter(). Also, if * you are viewing this documentation on an API reference site, the Core * hooks will be listed in this topic. * - Copy the function to your module's .module file. * - Change the name of the function, substituting your module's short name * (name of the module's directory, and .info.yml file without the extension) * for the "hook" part of the sample function name. For instance, to implement * hook_batch_alter(), you would rename it to my_module_batch_alter(). * - Edit the documentation for the function (normally, your implementation * should just have one line saying "Implements hook_batch_alter()."). * - Edit the body of the function, substituting in what you need your module * to do. * * To define a hook: * - Choose a unique name for your hook. It should start with "hook_", followed * by your module's short name. * - Provide documentation in a *.api.php file in your module's main * directory. See the "implementing" section above for details of what this * should contain (parameters, return value, and sample function body). * - Invoke the hook in your module's code. * * To invoke a hook, use methods on * \Drupal\Core\Extension\ModuleHandlerInterface such as alter(), invoke(), * and invokeAll(). You can obtain a module handler by calling * \Drupal::moduleHandler(), or getting the 'module_handler' service on an * injected container. * * @see extending * @see themeable * @see callbacks * @see \Drupal\Core\Extension\ModuleHandlerInterface * @see \Drupal::moduleHandler() * * @} */ /** * @defgroup callbacks Callbacks * @{ * Callback function signatures. * * Drupal's API sometimes uses callback functions to allow you to define how * some type of processing happens. A callback is a function with a defined * signature, which you define in a module. Then you pass the function name as * a parameter to a Drupal API function or return it as part of a hook * implementation return value, and your function is called at an appropriate * time. For instance, when setting up batch processing you might need to * provide a callback function for each processing step and/or a callback for * when processing is finished; you would do that by defining these functions * and passing their names into the batch setup function. * * Callback function signatures, like hook definitions, are described by * creating and documenting dummy functions in a *.api.php file; normally, the * dummy callback function's name should start with "callback_", and you should * document the parameters and return value and provide a sample function body. * Then your API documentation can refer to this callback function in its * documentation. A user of your API can usually name their callback function * anything they want, although a standard name would be to replace "callback_" * with the module name. * * @see hooks * @see themeable * * @} */ /** * @defgroup form_api Form generation * @{ * Describes how to generate and manipulate forms and process form submissions. * * Drupal provides a Form API in order to achieve consistency in its form * processing and presentation, while simplifying code and reducing the amount * of HTML that must be explicitly generated by a module. * * @section generating_forms Creating forms * Forms are defined as classes that implement the * \Drupal\Core\Form\FormInterface and are built using the * \Drupal\Core\Form\FormBuilder class. Drupal provides a couple of utility * classes that can be extended as a starting point for most basic forms, the * most commonly used of which is \Drupal\Core\Form\FormBase. FormBuilder * handles the low level processing of forms such as rendering the necessary * HTML, initial processing of incoming $_POST data, and delegating to your * implementation of FormInterface for validation and processing of submitted * data. * * Here is an example of a Form class: * @code * namespace Drupal\mymodule\Form; * * use Drupal\Core\Form\FormBase; * use Drupal\Core\Form\FormStateInterface; * * class ExampleForm extends FormBase { * public function getFormId() { * // Unique ID of the form. * return 'example_form'; * } * * public function buildForm(array $form, FormStateInterface $form_state) { * // Create a $form API array. * $form['phone_number'] = array( * '#type' => 'tel', * '#title' => $this->t('Your phone number'), * ); * $form['save'] = array( * '#type' => 'submit', * '#value' => $this->t('Save'), * ); * return $form; * } * * public function validateForm(array &$form, FormStateInterface $form_state) { * // Validate submitted form data. * } * * public function submitForm(array &$form, FormStateInterface $form_state) { * // Handle submitted form data. * } * } * @endcode * * @section retrieving_forms Retrieving and displaying forms * \Drupal::formBuilder()->getForm() should be used to handle retrieving, * processing, and displaying a rendered HTML form. Given the ExampleForm * defined above, * \Drupal::formBuilder()->getForm('Drupal\mymodule\Form\ExampleForm') would * return the rendered HTML of the form defined by ExampleForm::buildForm(), or * call the validateForm() and submitForm(), methods depending on the current * processing state. * * The argument to \Drupal::formBuilder()->getForm() is the name of a class that * implements FormInterface. Any additional arguments passed to the getForm() * method will be passed along as additional arguments to the * ExampleForm::buildForm() method. * * For example: * @code * $extra = '612-123-4567'; * $form = \Drupal::formBuilder()->getForm('Drupal\mymodule\Form\ExampleForm', $extra); * ... * public function buildForm(array $form, FormStateInterface $form_state, $extra = NULL) * $form['phone_number'] = array( * '#type' => 'tel', * '#title' => $this->t('Your phone number'), * '#value' => $extra, * ); * return $form; * } * @endcode * * Alternatively, forms can be built directly via the routing system which will * take care of calling \Drupal::formBuilder()->getForm(). The following example * demonstrates the use of a routing.yml file to display a form at the given * route. * * @code * example.form: * path: '/example-form' * defaults: * _title: 'Example form' * _form: '\Drupal\mymodule\Form\ExampleForm' * @endcode * * The $form argument to form-related functions is a specialized render array * containing the elements and properties of the form. For more about render * arrays, see the @link theme_render Render API topic. @endlink For more * detailed explanations of the Form API workflow, see the * @link https://www.drupal.org/node/2117411 Form API documentation section. @endlink * In addition, there is a set of Form API tutorials in the * @link https://www.drupal.org/project/examples Examples for Developers project. @endlink * * In the form builder, validation, submission, and other form methods, * $form_state is the primary influence on the processing of the form and is * passed to most methods, so they can use it to communicate with the form * system and each other. $form_state is an object that implements * \Drupal\Core\Form\FormStateInterface. * @} */ /** * @defgroup queue Queue operations * @{ * Queue items to allow later processing. * * The queue system allows placing items in a queue and processing them later. * The system tries to ensure that only one consumer can process an item. * * Before a queue can be used it needs to be created by * Drupal\Core\Queue\QueueInterface::createQueue(). * * Items can be added to the queue by passing an arbitrary data object to * Drupal\Core\Queue\QueueInterface::createItem(). * * To process an item, call Drupal\Core\Queue\QueueInterface::claimItem() and * specify how long you want to have a lease for working on that item. * When finished processing, the item needs to be deleted by calling * Drupal\Core\Queue\QueueInterface::deleteItem(). If the consumer dies, the * item will be made available again by the Drupal\Core\Queue\QueueInterface * implementation once the lease expires. Another consumer will then be able to * receive it when calling Drupal\Core\Queue\QueueInterface::claimItem(). * Due to this, the processing code should be aware that an item might be handed * over for processing more than once. * * The $item object used by the Drupal\Core\Queue\QueueInterface can contain * arbitrary metadata depending on the implementation. Systems using the * interface should only rely on the data property which will contain the * information passed to Drupal\Core\Queue\QueueInterface::createItem(). * The full queue item returned by Drupal\Core\Queue\QueueInterface::claimItem() * needs to be passed to Drupal\Core\Queue\QueueInterface::deleteItem() once * processing is completed. * * There are two kinds of queue backends available: reliable, which preserves * the order of messages and guarantees that every item will be executed at * least once. The non-reliable kind only does a best effort to preserve order * in messages and to execute them at least once but there is a small chance * that some items get lost. For example, some distributed back-ends like * Amazon SQS will be managing jobs for a large set of producers and consumers * where a strict FIFO ordering will likely not be preserved. Another example * would be an in-memory queue backend which might lose items if it crashes. * However, such a backend would be able to deal with significantly more writes * than a reliable queue and for many tasks this is more important. See * aggregator_cron() for an example of how to effectively use a non-reliable * queue. Another example is doing Twitter statistics -- the small possibility * of losing a few items is insignificant next to power of the queue being able * to keep up with writes. As described in the processing section, regardless * of the queue being reliable or not, the processing code should be aware that * an item might be handed over for processing more than once (because the * processing code might time out before it finishes). * @} */ /** * @defgroup annotation Annotations * @{ * Annotations for class discovery and metadata description. * * The Drupal plugin system has a set of reusable components that developers * can use, override, and extend in their modules. Most of the plugins use * annotations, which let classes register themselves as plugins and describe * their metadata. (Annotations can also be used for other purposes, though * at the moment, Drupal only uses them for the plugin system.) * * To annotate a class as a plugin, add code similar to the following to the * end of the documentation block immediately preceding the class declaration: * @code * * @ContentEntityType( * * id = "comment", * * label = @Translation("Comment"), * * ... * * base_table = "comment" * * ) * @endcode * * Note that you must use double quotes; single quotes will not work in * annotations. * * Some annotation types, which extend the "@ PluginID" annotation class, have * only a single 'id' key in their annotation. For these, it is possible to use * a shorthand annotation. For example: * @code * * @ViewsArea("entity") * @endcode * in place of * @code * * @ViewsArea( * * id = "entity" * *) * @endcode * * The available annotation classes are listed in this topic, and can be * identified when you are looking at the Drupal source code by having * "@ Annotation" in their documentation blocks (without the space after @). To * find examples of annotation for a particular annotation class, such as * EntityType, look for class files that have an @ annotation section using the * annotation class. * * @see plugin_translatable * @see plugin_context * * @} */ /** * @addtogroup hooks * @{ */ /** * Perform periodic actions. * * Modules that require some commands to be executed periodically can * implement hook_cron(). The engine will then call the hook whenever a cron * run happens, as defined by the administrator. Typical tasks managed by * hook_cron() are database maintenance, backups, recalculation of settings * or parameters, automated mailing, and retrieving remote data. * * Short-running or non-resource-intensive tasks can be executed directly in * the hook_cron() implementation. * * Long-running tasks and tasks that could time out, such as retrieving remote * data, sending email, and intensive file tasks, should use the queue API * instead of executing the tasks directly. To do this, first define one or * more queues via a \Drupal\Core\Annotation\QueueWorker plugin. Then, add items * that need to be processed to the defined queues. */ function hook_cron() { // Short-running operation example, not using a queue: // Delete all expired records since the last cron run. $expires = \Drupal::state()->get('mymodule.last_check', 0); \Drupal::database()->delete('mymodule_table') ->condition('expires', $expires, '>=') ->execute(); \Drupal::state()->set('mymodule.last_check', REQUEST_TIME); // Long-running operation example, leveraging a queue: // Queue news feeds for updates once their refresh interval has elapsed. $queue = \Drupal::queue('aggregator_feeds'); $ids = \Drupal::entityManager()->getStorage('aggregator_feed')->getFeedIdsToRefresh(); foreach (Feed::loadMultiple($ids) as $feed) { if ($queue->createItem($feed)) { // Add timestamp to avoid queueing item more than once. $feed->setQueuedTime(REQUEST_TIME); $feed->save(); } } $ids = \Drupal::entityQuery('aggregator_feed') ->condition('queued', REQUEST_TIME - (3600 * 6), '<') ->execute(); if ($ids) { $feeds = Feed::loadMultiple($ids); foreach ($feeds as $feed) { $feed->setQueuedTime(0); $feed->save(); } } } /** * Alter available data types for typed data wrappers. * * @param array $data_types * An array of data type information. * * @see hook_data_type_info() */ function hook_data_type_info_alter(&$data_types) { $data_types['email']['class'] = '\Drupal\mymodule\Type\Email'; } /** * Alter cron queue information before cron runs. * * Called by \Drupal\Core\Cron to allow modules to alter cron queue settings * before any jobs are processesed. * * @param array $queues * An array of cron queue information. * * @see \Drupal\Core\QueueWorker\QueueWorkerInterface * @see \Drupal\Core\Annotation\QueueWorker * @see \Drupal\Core\Cron */ function hook_queue_info_alter(&$queues) { // This site has many feeds so let's spend 90 seconds on each cron run // updating feeds instead of the default 60. $queues['aggregator_feeds']['cron']['time'] = 90; } /** * Alter an email message created with MailManagerInterface->mail(). * * hook_mail_alter() allows modification of email messages created and sent * with MailManagerInterface->mail(). Usage examples include adding and/or * changing message text, message fields, and message headers. * * Email messages sent using functions other than MailManagerInterface->mail() * will not invoke hook_mail_alter(). For example, a contributed module directly * calling the MailInterface->mail() or PHP mail() function will not invoke * this hook. All core modules use MailManagerInterface->mail() for messaging, * it is best practice but not mandatory in contributed modules. * * @param $message * An array containing the message data. Keys in this array include: * - 'id': * The MailManagerInterface->mail() id of the message. Look at module source * code or MailManagerInterface->mail() for possible id values. * - 'to': * The address or addresses the message will be sent to. The * formatting of this string must comply with RFC 2822. * - 'from': * The address the message will be marked as being from, which is * either a custom address or the site-wide default email address. * - 'subject': * Subject of the email to be sent. This must not contain any newline * characters, or the email may not be sent properly. * - 'body': * An array of strings or objects that implement * \Drupal\Component\Render\MarkupInterface containing the message text. The * message body is created by concatenating the individual array strings * into a single text string using "\n\n" as a separator. * - 'headers': * Associative array containing mail headers, such as From, Sender, * MIME-Version, Content-Type, etc. * - 'params': * An array of optional parameters supplied by the caller of * MailManagerInterface->mail() that is used to build the message before * hook_mail_alter() is invoked. * - 'language': * The language object used to build the message before hook_mail_alter() * is invoked. * - 'send': * Set to FALSE to abort sending this email message. * * @see \Drupal\Core\Mail\MailManagerInterface::mail() */ function hook_mail_alter(&$message) { if ($message['id'] == 'modulename_messagekey') { if (!example_notifications_optin($message['to'], $message['id'])) { // If the recipient has opted to not receive such messages, cancel // sending. $message['send'] = FALSE; return; } $message['body'][] = "--\nMail sent out from " . \Drupal::config('system.site')->get('name'); } } /** * Prepares a message based on parameters; * * This hook is called from MailManagerInterface->mail(). Note that hook_mail(), * unlike hook_mail_alter(), is only called on the $module argument to * MailManagerInterface->mail(), not all modules. * * @param $key * An identifier of the mail. * @param $message * An array to be filled in. Elements in this array include: * - id: An ID to identify the mail sent. Look at module source code or * MailManagerInterface->mail() for possible id values. * - to: The address or addresses the message will be sent to. The * formatting of this string must comply with RFC 2822. * - subject: Subject of the email to be sent. This must not contain any * newline characters, or the mail may not be sent properly. * MailManagerInterface->mail() sets this to an empty * string when the hook is invoked. * - body: An array of lines containing the message to be sent. Drupal will * format the correct line endings for you. MailManagerInterface->mail() * sets this to an empty array when the hook is invoked. The array may * contain either strings or objects implementing * \Drupal\Component\Render\MarkupInterface. * - from: The address the message will be marked as being from, which is * set by MailManagerInterface->mail() to either a custom address or the * site-wide default email address when the hook is invoked. * - headers: Associative array containing mail headers, such as From, * Sender, MIME-Version, Content-Type, etc. * MailManagerInterface->mail() pre-fills several headers in this array. * @param $params * An array of parameters supplied by the caller of * MailManagerInterface->mail(). * * @see \Drupal\Core\Mail\MailManagerInterface::mail() */ function hook_mail($key, &$message, $params) { $account = $params['account']; $context = $params['context']; $variables = [ '%site_name' => \Drupal::config('system.site')->get('name'), '%username' => $account->getDisplayName(), ]; if ($context['hook'] == 'taxonomy') { $entity = $params['entity']; $vocabulary = Vocabulary::load($entity->id()); $variables += [ '%term_name' => $entity->name, '%term_description' => $entity->description, '%term_id' => $entity->id(), '%vocabulary_name' => $vocabulary->label(), '%vocabulary_description' => $vocabulary->getDescription(), '%vocabulary_id' => $vocabulary->id(), ]; } // Node-based variable translation is only available if we have a node. if (isset($params['node'])) { /** @var \Drupal\node\NodeInterface $node */ $node = $params['node']; $variables += [ '%uid' => $node->getOwnerId(), '%url' => $node->url('canonical', ['absolute' => TRUE]), '%node_type' => node_get_type_label($node), '%title' => $node->getTitle(), '%teaser' => $node->teaser, '%body' => $node->body, ]; } $subject = strtr($context['subject'], $variables); $body = strtr($context['message'], $variables); $message['subject'] .= str_replace(["\r", "\n"], '', $subject); $message['body'][] = MailFormatHelper::htmlToText($body); } /** * Alter the list of mail backend plugin definitions. * * @param array $info * The mail backend plugin definitions to be altered. * * @see \Drupal\Core\Annotation\Mail * @see \Drupal\Core\Mail\MailManager */ function hook_mail_backend_info_alter(&$info) { unset($info['test_mail_collector']); } /** * Alter the default country list. * * @param $countries * The associative array of countries keyed by two-letter country code. * * @see \Drupal\Core\Locale\CountryManager::getList() */ function hook_countries_alter(&$countries) { // Elbonia is now independent, so add it to the country list. $countries['EB'] = 'Elbonia'; } /** * Alter display variant plugin definitions. * * @param array $definitions * The array of display variant definitions, keyed by plugin ID. * * @see \Drupal\Core\Display\VariantManager * @see \Drupal\Core\Display\Annotation\DisplayVariant */ function hook_display_variant_plugin_alter(array &$definitions) { $definitions['full_page']['admin_label'] = t('Block layout'); } /** * Allow modules to alter layout plugin definitions. * * @param \Drupal\Core\Layout\LayoutDefinition[] $definitions * The array of layout definitions, keyed by plugin ID. */ function hook_layout_alter(&$definitions) { // Remove a layout. unset($definitions['twocol']); } /** * Flush all persistent and static caches. * * This hook asks your module to clear all of its static caches, * in order to ensure a clean environment for subsequently * invoked data rebuilds. * * Do NOT use this hook for rebuilding information. Only use it to flush custom * caches. * * Static caches using drupal_static() do not need to be reset manually. * However, all other static variables that do not use drupal_static() must be * manually reset. * * This hook is invoked by drupal_flush_all_caches(). It runs before module data * is updated and before hook_rebuild(). * * @see drupal_flush_all_caches() * @see hook_rebuild() */ function hook_cache_flush() { if (defined('MAINTENANCE_MODE') && MAINTENANCE_MODE == 'update') { _update_cache_clear(); } } /** * Rebuild data based upon refreshed caches. * * This hook allows your module to rebuild its data based on the latest/current * module data. It runs after hook_cache_flush() and after all module data has * been updated. * * This hook is only invoked after the system has been completely cleared; * i.e., all previously cached data is known to be gone and every API in the * system is known to return current information, so your module can safely rely * on all available data to rebuild its own. * * @see hook_cache_flush() * @see drupal_flush_all_caches() */ function hook_rebuild() { $themes = \Drupal::service('theme_handler')->listInfo(); foreach ($themes as $theme) { _block_rehash($theme->getName()); } } /** * Alter the configuration synchronization steps. * * @param array $sync_steps * A one-dimensional array of \Drupal\Core\Config\ConfigImporter method names * or callables that are invoked to complete the import, in the order that * they will be processed. Each callable item defined in $sync_steps should * either be a global function or a public static method. The callable should * accept a $context array by reference. For example: * * function _additional_configuration_step(&$context) { * // Do stuff. * // If finished set $context['finished'] = 1. * } * * For more information on creating batches, see the * @link batch Batch operations @endlink documentation. * * @see callback_batch_operation() * @see \Drupal\Core\Config\ConfigImporter::initialize() */ function hook_config_import_steps_alter(&$sync_steps, \Drupal\Core\Config\ConfigImporter $config_importer) { $deletes = $config_importer->getUnprocessedConfiguration('delete'); if (isset($deletes['field.storage.node.body'])) { $sync_steps[] = '_additional_configuration_step'; } } /** * Alter config typed data definitions. * * For example you can alter the typed data types representing each * configuration schema type to change default labels or form element renderers * used for configuration translation. * * If implementations of this hook add or remove configuration schema a * ConfigSchemaAlterException will be thrown. Keep in mind that there are tools * that may use the configuration schema for static analysis of configuration * files, like the string extractor for the localization system. Such systems * won't work with dynamically defined configuration schemas. * * For adding new data types use configuration schema YAML files instead. * * @param $definitions * Associative array of configuration type definitions keyed by schema type * names. The elements are themselves array with information about the type. * * @see \Drupal\Core\Config\TypedConfigManager * @see \Drupal\Core\Config\Schema\ConfigSchemaAlterException */ function hook_config_schema_info_alter(&$definitions) { // Enhance the text and date type definitions with classes to generate proper // form elements in ConfigTranslationFormBase. Other translatable types will // appear as a one line textfield. $definitions['text']['form_element_class'] = '\Drupal\config_translation\FormElement\Textarea'; $definitions['date_format']['form_element_class'] = '\Drupal\config_translation\FormElement\DateFormat'; } /** * Alter validation constraint plugin definitions. * * @param array[] $definitions * The array of validation constraint definitions, keyed by plugin ID. * * @see \Drupal\Core\Validation\ConstraintManager * @see \Drupal\Core\Validation\Annotation\Constraint */ function hook_validation_constraint_alter(array &$definitions) { $definitions['Null']['class'] = '\Drupal\mymodule\Validator\Constraints\MyClass'; } /** * @} End of "addtogroup hooks". */ /** * @defgroup ajax Ajax API * @{ * Overview for Drupal's Ajax API. * * @section sec_overview Overview of Ajax * Ajax is the process of dynamically updating parts of a page's HTML based on * data from the server. When a specified event takes place, a PHP callback is * triggered, which performs server-side logic and may return updated markup or * JavaScript commands to run. After the return, the browser runs the JavaScript * or updates the markup on the fly, with no full page refresh necessary. * * Many different events can trigger Ajax responses, including: * - Clicking a button * - Pressing a key * - Moving the mouse * * @section sec_framework Ajax responses in forms * Forms that use the Drupal Form API (see the * @link form_api Form API topic @endlink for more information about forms) can * trigger AJAX responses. Here is an outline of the steps: * - Add property '#ajax' to a form element in your form array, to trigger an * Ajax response. * - Write an Ajax callback to process the input and respond. * See sections below for details on these two steps. * * @subsection sub_form Adding Ajax triggers to a form * As an example of adding Ajax triggers to a form, consider editing a date * format, where the user is provided with a sample of the generated date output * as they type. To accomplish this, typing in the text field should trigger an * Ajax response. This is done in the text field form array element * in \Drupal\config_translation\FormElement\DateFormat::getFormElement(): * @code * '#ajax' => array( * 'callback' => 'Drupal\config_translation\FormElement\DateFormat::ajaxSample', * 'event' => 'keyup', * 'progress' => array( * 'type' => 'throbber', * 'message' => NULL, * ), * ), * @endcode * * As you can see from this example, the #ajax property for a form element is * an array. Here are the details of its elements, all of which are optional: * - callback: The callback to invoke to handle the server side of the * Ajax event. More information on callbacks is below in @ref sub_callback. * - wrapper: The HTML 'id' attribute of the area where the content returned by * the callback should be placed. Note that callbacks have a choice of * returning content or JavaScript commands; 'wrapper' is used for content * returns. * - method: The jQuery method for placing the new content (used with * 'wrapper'). Valid options are 'replaceWith' (default), 'append', 'prepend', * 'before', 'after', or 'html'. See * http://api.jquery.com/category/manipulation/ for more information on these * methods. * - effect: The jQuery effect to use when placing the new HTML (used with * 'wrapper'). Valid options are 'none' (default), 'slide', or 'fade'. * - speed: The effect speed to use (used with 'effect' and 'wrapper'). Valid * options are 'slow' (default), 'fast', or the number of milliseconds the * effect should run. * - event: The JavaScript event to respond to. This is selected automatically * for the type of form element; provide a value to override the default. * - prevent: A JavaScript event to prevent when the event is triggered. For * example, if you use event 'mousedown' on a button, you might want to * prevent 'click' events from also being triggered. * - progress: An array indicating how to show Ajax processing progress. Can * contain one or more of these elements: * - type: Type of indicator: 'throbber' (default) or 'bar'. * - message: Translated message to display. * - url: For a bar progress indicator, URL path for determining progress. * - interval: For a bar progress indicator, how often to update it. * - url: A \Drupal\Core\Url to which to submit the Ajax request. If omitted, * defaults to either the same URL as the form or link destination is for * someone with JavaScript disabled, or a slightly modified version (e.g., * with a query parameter added, removed, or changed) of that URL if * necessary to support Drupal's content negotiation. It is recommended to * omit this key and use Drupal's content negotiation rather than using * substantially different URLs between Ajax and non-Ajax. * * @subsection sub_callback Setting up a callback to process Ajax * Once you have set up your form to trigger an Ajax response (see @ref sub_form * above), you need to write some PHP code to process the response. If you use * 'path' in your Ajax set-up, your route controller will be triggered with only * the information you provide in the URL. If you use 'callback', your callback * method is a function, which will receive the $form and $form_state from the * triggering form. You can use $form_state to get information about the * data the user has entered into the form. For instance, in the above example * for the date format preview, * \Drupal\config_translation\FormElement\DateFormat\ajaxSample() does this to * get the format string entered by the user: * @code * $format_value = \Drupal\Component\Utility\NestedArray::getValue( * $form_state->getValues(), * $form_state->getTriggeringElement()['#array_parents']); * @endcode * * Once you have processed the input, you have your choice of returning HTML * markup or a set of Ajax commands. If you choose to return HTML markup, you * can return it as a string or a renderable array, and it will be placed in * the defined 'wrapper' element (see documentation above in @ref sub_form). * In addition, any messages returned by drupal_get_messages(), themed as in * status-messages.html.twig, will be prepended. * * To return commands, you need to set up an object of class * \Drupal\Core\Ajax\AjaxResponse, and then use its addCommand() method to add * individual commands to it. In the date format preview example, the format * output is calculated, and then it is returned as replacement markup for a div * like this: * @code * $response = new AjaxResponse(); * $response->addCommand(new ReplaceCommand( * '#edit-date-format-suffix', * '' . $format . '')); * return $response; * @endcode * * The individual commands that you can return implement interface * \Drupal\Core\Ajax\CommandInterface. Available commands provide the ability * to pop up alerts, manipulate text and markup in various ways, redirect * to a new URL, and the generic \Drupal\Core\Ajax\InvokeCommand, which * invokes an arbitrary jQuery command. * * As noted above, status messages are prepended automatically if you use the * 'wrapper' method and return HTML markup. This is not the case if you return * commands, but if you would like to show status messages, you can add * @code * array('#type' => 'status_messages') * @endcode * to a render array, use drupal_render() to render it, and add a command to * place the messages in an appropriate location. * * @section sec_other Other methods for triggering Ajax * Here are some additional methods you can use to trigger Ajax responses in * Drupal: * - Add class 'use-ajax' to a link. The link will be loaded using an Ajax * call. When using this method, the href of the link can contain '/nojs/' as * part of the path. When the Ajax JavaScript processes the page, it will * convert this to '/ajax/'. The server is then able to easily tell if this * request was made through an actual Ajax request or in a degraded state, and * respond appropriately. * - Add class 'use-ajax-submit' to a submit button in a form. The form will * then be submitted via Ajax to the path specified in the #action. Like the * ajax-submit class on links, this path will have '/nojs/' replaced with * '/ajax/' so that the submit handler can tell if the form was submitted in a * degraded state or not. * - Add property '#autocomplete_route_name' to a text field in a form. The * route controller for this route must return an array of options for * autocomplete, as a \Symfony\Component\HttpFoundation\JsonResponse object. * See the @link menu Routing topic @endlink for more information about * routing. */ /** * @} End of "defgroup ajax". */ /** * @defgroup service_tag Service Tags * @{ * Service tags overview * * Some services have tags, which are defined in the service definition. Tags * are used to define a group of related services, or to specify some aspect of * how the service behaves. Typically, if you tag a service, your service class * must also implement a corresponding interface. Some common examples: * - access_check: Indicates a route access checking service; see the * @link menu Menu and routing system topic @endlink for more information. * - cache.bin: Indicates a cache bin service; see the * @link cache Cache topic @endlink for more information. * - event_subscriber: Indicates an event subscriber service. Event subscribers * can be used for dynamic routing and route altering; see the * @link menu Menu and routing system topic @endlink for more information. * They can also be used for other purposes; see * http://symfony.com/doc/current/cookbook/doctrine/event_listeners_subscribers.html * for more information. * - needs_destruction: Indicates that a destruct() method needs to be called * at the end of a request to finalize operations, if this service was * instantiated. Services should implement \Drupal\Core\DestructableInterface * in this case. * - context_provider: Indicates a block context provider, used for example * by block conditions. It has to implement * \Drupal\Core\Plugin\Context\ContextProviderInterface. * - http_client_middleware: Indicates that the service provides a guzzle * middleware, see * https://guzzle.readthedocs.org/en/latest/handlers-and-middleware.html for * more information. * * Creating a tag for a service does not do anything on its own, but tags * can be discovered or queried in a compiler pass when the container is built, * and a corresponding action can be taken. See * \Drupal\Core\Render\MainContent\MainContentRenderersPass for an example of * finding tagged services. * * See @link container Services and Dependency Injection Container @endlink for * information on services and the dependency injection container. * * @} */ /** * @defgroup events Events * @{ * Overview of event dispatch and subscribing * * @section sec_intro Introduction and terminology * Events are part of the Symfony framework: they allow for different components * of the system to interact and communicate with each other. Each event has a * unique string name. One system component dispatches the event at an * appropriate time; many events are dispatched by Drupal core and the Symfony * framework in every request. Other system components can register as event * subscribers; when an event is dispatched, a method is called on each * registered subscriber, allowing each one to react. For more on the general * concept of events, see * http://symfony.com/doc/current/components/event_dispatcher/introduction.html * * @section sec_dispatch Dispatching events * To dispatch an event, call the * \Symfony\Component\EventDispatcher\EventDispatcherInterface::dispatch() * method on the 'event_dispatcher' service (see the * @link container Services topic @endlink for more information about how to * interact with services). The first argument is the unique event name, which * you should normally define as a constant in a separate static class (see * \Symfony\Component\HttpKernel\KernelEvents and * \Drupal\Core\Config\ConfigEvents for examples). The second argument is a * \Symfony\Component\EventDispatcher\Event object; normally you will need to * extend this class, so that your event class can provide data to the event * subscribers. * * @section sec_subscribe Registering event subscribers * Here are the steps to register an event subscriber: * - Define a service in your module, tagged with 'event_subscriber' (see the * @link container Services topic @endlink for instructions). * - Define a class for your subscriber service that implements * \Symfony\Component\EventDispatcher\EventSubscriberInterface * - In your class, the getSubscribedEvents method returns a list of the events * this class is subscribed to, and which methods on the class should be * called for each one. Example: * @code * public static function getSubscribedEvents() { * // Subscribe to kernel terminate with priority 100. * $events[KernelEvents::TERMINATE][] = array('onTerminate', 100); * // Subscribe to kernel request with default priority of 0. * $events[KernelEvents::REQUEST][] = array('onRequest'); * return $events; * } * @endcode * - Write the methods that respond to the events; each one receives the * event object provided in the dispatch as its one argument. In the above * example, you would need to write onTerminate() and onRequest() methods. * * Note that in your getSubscribedEvents() method, you can optionally set the * priority of your event subscriber (see terminate example above). Event * subscribers with higher priority numbers get executed first; the default * priority is zero. If two event subscribers for the same event have the same * priority, the one defined in a module with a lower module weight will fire * first. Subscribers defined in the same services file are fired in * definition order. If order matters defining a priority is strongly advised * instead of relying on these two tie breaker rules as they might change in a * minor release. * @} */