first import

sites/all/modules/ctools/plugins/relationships/book_parent.inc

@@ -0,0 +1,66 @@
+<?php
+
+/**
+ * @file
+ * Plugin to provide an relationship handler for book parent.
+ */
+
+/**
+ * Plugins are described by creating a $plugin array which will be used
+ * by the system that includes this file.
+ */
+$plugin = array(
+  'title' => t('Book parent'),
+  'keyword' => 'book_parent',
+  'description' => t('Adds a book parent from a node context.'),
+  'required context' => new ctools_context_required(t('Node'), 'node'),
+  'context' => 'ctools_book_parent_context',
+  'edit form' => 'ctools_book_parent_settings_form',
+  'defaults' => array('type' => 'top'),
+);
+
+/**
+ * Return a new context based on an existing context.
+ */
+function ctools_book_parent_context($context, $conf) {
+  // If unset it wants a generic, unfilled context, which is just NULL.
+  if (empty($context->data)) {
+    return ctools_context_create_empty('node');
+  }
+
+  if (isset($context->data->book)) {
+    if ($conf['type'] == 'top') {
+      $nid = $context->data->book['bid'];
+    }
+    else {
+      // Just load the parent book.
+      $item = book_link_load($context->data->book['plid']);
+      $nid = $item['nid'];
+    }
+
+    if (!empty($nid)) {
+      // Load the node.
+      $node = node_load($nid);
+      // Generate the context.
+      return ctools_context_create('node', $node);
+    }
+  }
+  else {
+    return ctools_context_create_empty('node');
+  }
+}
+
+/**
+ * Settings form for the relationship.
+ */
+function ctools_book_parent_settings_form($form, &$form_state) {
+  $conf = $form_state['conf'];
+  $form['type'] = array(
+    '#type' => 'select',
+    '#title' => t('Relationship type'),
+    '#options' => array('parent' => t('Immediate parent'), 'top' => t('Top level book')),
+    '#default_value' => $conf['type'],
+  );
+
+  return $form;
+}