cms/drupal/modules/field/field.attach.inc
changeset 541 e756a8c72c3d
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cms/drupal/modules/field/field.attach.inc	Fri Sep 08 12:04:06 2017 +0200
@@ -0,0 +1,1416 @@
+<?php
+
+/**
+ * @file
+ * Field attach API, allowing entities (nodes, users, ...) to be 'fieldable'.
+ */
+
+/**
+ * Exception thrown by field_attach_validate() on field validation errors.
+ */
+class FieldValidationException extends FieldException {
+  var $errors;
+
+ /**
+  * Constructor for FieldValidationException.
+  *
+  * @param $errors
+  *   An array of field validation errors, keyed by field name and
+  *   delta that contains two keys:
+  *   - 'error': A machine-readable error code string, prefixed by
+  *     the field module name. A field widget may use this code to decide
+  *     how to report the error.
+  *   - 'message': A human-readable error message such as to be
+  *     passed to form_error() for the appropriate form element.
+  */
+  function __construct($errors) {
+    $this->errors = $errors;
+    parent::__construct(t('Field validation errors'));
+  }
+}
+
+/**
+ * @defgroup field_storage Field Storage API
+ * @{
+ * Implement a storage engine for Field API data.
+ *
+ * The Field Attach API uses the Field Storage API to perform all "database
+ * access". Each Field Storage API hook function defines a primitive database
+ * operation such as read, write, or delete. The default field storage module,
+ * field_sql_storage.module, uses the local SQL database to implement these
+ * operations, but alternative field storage backends can choose to represent
+ * the data in SQL differently or use a completely different storage mechanism
+ * such as a cloud-based database.
+ *
+ * Each field defines which storage backend it uses. The Drupal system variable
+ * 'field_storage_default' identifies the storage backend used by default.
+ *
+ * See @link field Field API @endlink for information about the other parts of
+ * the Field API.
+ */
+
+/**
+ * Argument for an update operation.
+ *
+ * This is used in hook_field_storage_write when updating an
+ * existing entity.
+ */
+define('FIELD_STORAGE_UPDATE', 'update');
+
+/**
+ * Argument for an insert operation.
+ *
+ * This is used in hook_field_storage_write when inserting a new entity.
+ */
+define('FIELD_STORAGE_INSERT', 'insert');
+
+/**
+ * @} End of "defgroup field_storage".
+ */
+
+/**
+ * @defgroup field_attach Field Attach API
+ * @{
+ * Operate on Field API data attached to Drupal entities.
+ *
+ * Field Attach API functions load, store, display, generate Field API
+ * structures, and perform a variety of other functions for field data attached
+ * to individual entities.
+ *
+ * Field Attach API functions generally take $entity_type and $entity arguments
+ * along with additional function-specific arguments. $entity_type is the type
+ * of the fieldable entity, such as 'node' or 'user', and $entity is the entity
+ * itself.
+ *
+ * hook_entity_info() is the central place for entity types to define if and
+ * how Field API should operate on their entity objects. Notably, the
+ * 'fieldable' property needs to be set to TRUE.
+ *
+ * The Field Attach API uses the concept of bundles: the set of fields for a
+ * given entity is defined on a per-bundle basis. The collection of bundles for
+ * an entity type is defined its hook_entity_info() implementation. For
+ * instance, node_entity_info() exposes each node type as its own bundle. This
+ * means that the set of fields of a node is determined by the node type. The
+ * Field API reads the bundle name for a given entity from a particular
+ * property of the entity object, and hook_entity_info() defines which property
+ * to use. For instance, node_entity_info() specifies:
+ * @code $info['entity keys']['bundle'] = 'type'@endcode
+ * This indicates that for a particular node object, the bundle name can be
+ * found in $node->type. This property can be omitted if the entity type only
+ * exposes a single bundle (all entities of this type have the same collection
+ * of fields). This is the case for the 'user' entity type.
+ *
+ * Most Field Attach API functions define a corresponding hook function that
+ * allows any module to act on Field Attach operations for any entity after the
+ * operation is complete, and access or modify all the field, form, or display
+ * data for that entity and operation. For example, field_attach_view() invokes
+ * hook_field_attach_view_alter(). These all-module hooks are distinct from
+ * those of the Field Types API, such as hook_field_load(), that are only
+ * invoked for the module that defines a specific field type.
+ *
+ * field_attach_load(), field_attach_insert(), and field_attach_update() also
+ * define pre-operation hooks, e.g. hook_field_attach_pre_load(). These hooks
+ * run before the corresponding Field Storage API and Field Type API
+ * operations. They allow modules to define additional storage locations (e.g.
+ * denormalizing, mirroring) for field data on a per-field basis. They also
+ * allow modules to take over field storage completely by instructing other
+ * implementations of the same hook and the Field Storage API itself not to
+ * operate on specified fields.
+ *
+ * The pre-operation hooks do not make the Field Storage API irrelevant. The
+ * Field Storage API is essentially the "fallback mechanism" for any fields
+ * that aren't being intercepted explicitly by pre-operation hooks.
+ *
+ * @link field_language Field Language API @endlink provides information about
+ * the structure of field objects.
+ *
+ * See @link field Field API @endlink for information about the other parts of
+ * the Field API.
+ */
+
+/**
+ * Invoke a field hook.
+ *
+ * @param $op
+ *   Possible operations include:
+ *   - form
+ *   - validate
+ *   - presave
+ *   - insert
+ *   - update
+ *   - delete
+ *   - delete revision
+ *   - view
+ *   - prepare translation
+ * @param $entity_type
+ *   The type of $entity; e.g. 'node' or 'user'.
+ * @param $entity
+ *   The fully formed $entity_type entity.
+ * @param $a
+ *   - The $form in the 'form' operation.
+ *   - The value of $view_mode in the 'view' operation.
+ *   - Otherwise NULL.
+ * @param $b
+ *   - The $form_state in the 'submit' operation.
+ *   - Otherwise NULL.
+ * @param $options
+ *   An associative array of additional options, with the following keys:
+ *  - 'field_name': The name of the field whose operation should be
+ *    invoked. By default, the operation is invoked on all the fields
+ *    in the entity's bundle. NOTE: This option is not compatible with
+ *    the 'deleted' option; the 'field_id' option should be used
+ *    instead.
+ *  - 'field_id': The id of the field whose operation should be
+ *    invoked. By default, the operation is invoked on all the fields
+ *    in the entity's' bundles.
+ *  - 'default': A boolean value, specifying which implementation of
+ *    the operation should be invoked.
+ *    - if FALSE (default), the field types implementation of the operation
+ *      will be invoked (hook_field_[op])
+ *    - If TRUE, the default field implementation of the field operation
+ *      will be invoked (field_default_[op])
+ *    Internal use only. Do not explicitely set to TRUE, but use
+ *    _field_invoke_default() instead.
+ *  - 'deleted': If TRUE, the function will operate on deleted fields
+ *    as well as non-deleted fields. If unset or FALSE, only
+ *    non-deleted fields are operated on.
+ *  - 'language': A language code or an array of language codes keyed by field
+ *    name. It will be used to narrow down to a single value the available
+ *    languages to act on.
+ */
+function _field_invoke($op, $entity_type, $entity, &$a = NULL, &$b = NULL, $options = array()) {
+  // Merge default options.
+  $default_options = array(
+    'default' => FALSE,
+    'deleted' => FALSE,
+    'language' => NULL,
+  );
+  $options += $default_options;
+
+  // Determine the list of instances to iterate on.
+  list(, , $bundle) = entity_extract_ids($entity_type, $entity);
+  $instances = _field_invoke_get_instances($entity_type, $bundle, $options);
+
+  // Iterate through the instances and collect results.
+  $return = array();
+  foreach ($instances as $instance) {
+    // field_info_field() is not available for deleted fields, so use
+    // field_info_field_by_id().
+    $field = field_info_field_by_id($instance['field_id']);
+    $field_name = $field['field_name'];
+    $function = $options['default'] ? 'field_default_' . $op : $field['module'] . '_field_' . $op;
+    if (function_exists($function)) {
+      // Determine the list of languages to iterate on.
+      $available_languages = field_available_languages($entity_type, $field);
+      $languages = _field_language_suggestion($available_languages, $options['language'], $field_name);
+
+      foreach ($languages as $langcode) {
+        $items = isset($entity->{$field_name}[$langcode]) ? $entity->{$field_name}[$langcode] : array();
+        $result = $function($entity_type, $entity, $field, $instance, $langcode, $items, $a, $b);
+        if (isset($result)) {
+          // For hooks with array results, we merge results together.
+          // For hooks with scalar results, we collect results in an array.
+          if (is_array($result)) {
+            $return = array_merge($return, $result);
+          }
+          else {
+            $return[] = $result;
+          }
+        }
+
+        // Populate $items back in the field values, but avoid replacing missing
+        // fields with an empty array (those are not equivalent on update).
+        if ($items !== array() || isset($entity->{$field_name}[$langcode])) {
+          $entity->{$field_name}[$langcode] = $items;
+        }
+      }
+    }
+  }
+
+  return $return;
+}
+
+/**
+ * Invoke a field hook across fields on multiple entities.
+ *
+ * @param $op
+ *   Possible operations include:
+ *   - load
+ *   - prepare_view
+ *   For all other operations, use _field_invoke() / field_invoke_default()
+ *   instead.
+ * @param $entity_type
+ *   The type of $entity; e.g. 'node' or 'user'.
+ * @param $entities
+ *   An array of entities, keyed by entity id.
+ * @param $a
+ *   - The $age parameter in the 'load' operation.
+ *   - Otherwise NULL.
+ * @param $b
+ *   Currently always NULL.
+ * @param $options
+ *   An associative array of additional options, with the following keys:
+ *  - 'field_name': The name of the field whose operation should be
+ *    invoked. By default, the operation is invoked on all the fields
+ *    in the entity's bundle. NOTE: This option is not compatible with
+ *    the 'deleted' option; the 'field_id' option should be used instead.
+ *  - 'field_id': The id of the field whose operation should be
+ *    invoked. By default, the operation is invoked on all the fields
+ *    in the entity's' bundles.
+ *  - 'default': A boolean value, specifying which implementation of
+ *    the operation should be invoked.
+ *    - if FALSE (default), the field types implementation of the operation
+ *      will be invoked (hook_field_[op])
+ *    - If TRUE, the default field implementation of the field operation
+ *      will be invoked (field_default_[op])
+ *    Internal use only. Do not explicitely set to TRUE, but use
+ *    _field_invoke_multiple_default() instead.
+ *  - 'deleted': If TRUE, the function will operate on deleted fields
+ *    as well as non-deleted fields. If unset or FALSE, only
+ *    non-deleted fields are operated on.
+ *  - 'language': A language code or an array of arrays of language codes keyed
+ *    by entity id and field name. It will be used to narrow down to a single
+ *    value the available languages to act on.
+ *
+ * @return
+ *   An array of returned values keyed by entity id.
+ */
+function _field_invoke_multiple($op, $entity_type, $entities, &$a = NULL, &$b = NULL, $options = array()) {
+  // Merge default options.
+  $default_options = array(
+    'default' => FALSE,
+    'deleted' => FALSE,
+    'language' => NULL,
+  );
+  $options += $default_options;
+
+  $fields = array();
+  $grouped_instances = array();
+  $grouped_entities = array();
+  $grouped_items = array();
+  $return = array();
+
+  // Go through the entities and collect the fields on which the hook should be
+  // invoked.
+  //
+  // We group fields by id, not by name, because this function can operate on
+  // deleted fields which may have non-unique names. However, entities can only
+  // contain data for a single field for each name, even if that field
+  // is deleted, so we reference field data via the
+  // $entity->$field_name property.
+  foreach ($entities as $entity) {
+    // Determine the list of instances to iterate on.
+    list($id, $vid, $bundle) = entity_extract_ids($entity_type, $entity);
+    $instances = _field_invoke_get_instances($entity_type, $bundle, $options);
+
+    foreach ($instances as $instance) {
+      $field_id = $instance['field_id'];
+      $field_name = $instance['field_name'];
+      $field = field_info_field_by_id($field_id);
+      $function = $options['default'] ? 'field_default_' . $op : $field['module'] . '_field_' . $op;
+      if (function_exists($function)) {
+        // Add the field to the list of fields to invoke the hook on.
+        if (!isset($fields[$field_id])) {
+          $fields[$field_id] = $field;
+        }
+        // Extract the field values into a separate variable, easily accessed
+        // by hook implementations.
+        // Unless a language suggestion is provided we iterate on all the
+        // available languages.
+        $available_languages = field_available_languages($entity_type, $field);
+        $language = is_array($options['language']) && !empty($options['language'][$id]) ? $options['language'][$id] : $options['language'];
+        $languages = _field_language_suggestion($available_languages, $language, $field_name);
+        foreach ($languages as $langcode) {
+          $grouped_items[$field_id][$langcode][$id] = isset($entity->{$field_name}[$langcode]) ? $entity->{$field_name}[$langcode] : array();
+          // Group the instances and entities corresponding to the current
+          // field.
+          $grouped_instances[$field_id][$langcode][$id] = $instance;
+          $grouped_entities[$field_id][$langcode][$id] = $entities[$id];
+        }
+      }
+    }
+    // Initialize the return value for each entity.
+    $return[$id] = array();
+  }
+
+  // For each field, invoke the field hook and collect results.
+  foreach ($fields as $field_id => $field) {
+    $field_name = $field['field_name'];
+    $function = $options['default'] ? 'field_default_' . $op : $field['module'] . '_field_' . $op;
+    // Iterate over all the field translations.
+    foreach ($grouped_items[$field_id] as $langcode => &$items) {
+      $entities = $grouped_entities[$field_id][$langcode];
+      $instances = $grouped_instances[$field_id][$langcode];
+      $results = $function($entity_type, $entities, $field, $instances, $langcode, $items, $a, $b);
+      if (isset($results)) {
+        // Collect results by entity.
+        // For hooks with array results, we merge results together.
+        // For hooks with scalar results, we collect results in an array.
+        foreach ($results as $id => $result) {
+          if (is_array($result)) {
+            $return[$id] = array_merge($return[$id], $result);
+          }
+          else {
+            $return[$id][] = $result;
+          }
+        }
+      }
+    }
+
+    // Populate field values back in the entities, but avoid replacing missing
+    // fields with an empty array (those are not equivalent on update).
+    foreach ($grouped_entities[$field_id] as $langcode => $entities) {
+      foreach ($entities as $id => $entity) {
+        if ($grouped_items[$field_id][$langcode][$id] !== array() || isset($entity->{$field_name}[$langcode])) {
+          $entity->{$field_name}[$langcode] = $grouped_items[$field_id][$langcode][$id];
+        }
+      }
+    }
+  }
+
+  return $return;
+}
+
+/**
+ * Invoke field.module's version of a field hook.
+ *
+ * This function invokes the field_default_[op]() function.
+ * Use _field_invoke() to invoke the field type implementation,
+ * hook_field_[op]().
+ *
+ * @see _field_invoke()
+ */
+function _field_invoke_default($op, $entity_type, $entity, &$a = NULL, &$b = NULL, $options = array()) {
+  $options['default'] = TRUE;
+  return _field_invoke($op, $entity_type, $entity, $a, $b, $options);
+}
+
+/**
+ * Invoke field.module's version of a field hook on multiple entities.
+ *
+ * This function invokes the field_default_[op]() function.
+ * Use _field_invoke_multiple() to invoke the field type implementation,
+ * hook_field_[op]().
+ *
+ * @see _field_invoke_multiple()
+ */
+function _field_invoke_multiple_default($op, $entity_type, $entities, &$a = NULL, &$b = NULL, $options = array()) {
+  $options['default'] = TRUE;
+  return _field_invoke_multiple($op, $entity_type, $entities, $a, $b, $options);
+}
+
+/**
+ * Helper for _field_invoke(): retrieves a list of instances to operate on.
+ *
+ * @param $entity_type
+ *   The entity type.
+ * @param $bundle
+ *   The bundle name.
+ * @param $options
+ *   An associative array of options, as provided to _field_invoke(). Only the
+ *   following keys are considered :
+ *   - deleted
+ *   - field_name
+ *   - field_id
+ *   See _field_invoke() for details.
+ *
+ * @return
+ *   The array of selected instance definitions.
+ */
+function _field_invoke_get_instances($entity_type, $bundle, $options) {
+  if ($options['deleted']) {
+    // Deleted fields are not included in field_info_instances(), and need to
+    // be fetched from the database with field_read_instances().
+    $params = array('entity_type' => $entity_type, 'bundle' => $bundle);
+    if (isset($options['field_id'])) {
+      // Single-field mode by field id: field_read_instances() does the filtering.
+      // Single-field mode by field name is not compatible with the 'deleted'
+      // option.
+      $params['field_id'] = $options['field_id'];
+    }
+    $instances = field_read_instances($params, array('include_deleted' => TRUE));
+  }
+  elseif (isset($options['field_name'])) {
+    // Single-field mode by field name: field_info_instance() does the
+    // filtering.
+    $instances = array(field_info_instance($entity_type, $options['field_name'], $bundle));
+  }
+  else {
+    $instances = field_info_instances($entity_type, $bundle);
+    if (isset($options['field_id'])) {
+      // Single-field mode by field id: we need to loop on each instance to
+      // find the right one.
+      foreach ($instances as $instance) {
+        if ($instance['field_id'] == $options['field_id']) {
+          $instances = array($instance);
+          break;
+        }
+      }
+    }
+  }
+
+  return $instances;
+}
+
+/**
+ * Add form elements for all fields for an entity to a form structure.
+ *
+ * The form elements for the entity's fields are added by reference as direct
+ * children in the $form parameter. This parameter can be a full form structure
+ * (most common case for entity edit forms), or a sub-element of a larger form.
+ *
+ * By default, submitted field values appear at the top-level of
+ * $form_state['values']. A different location within $form_state['values'] can
+ * be specified by setting the '#parents' property on the incoming $form
+ * parameter. Because of name clashes, two instances of the same field cannot
+ * appear within the same $form element, or within the same '#parents' space.
+ *
+ * For each call to field_attach_form(), field values are processed by calling
+ * field_attach_form_validate() and field_attach_submit() on the same $form
+ * element.
+ *
+ * Sample resulting structure in $form:
+ * @code
+ *   '#parents' => The location of field values in $form_state['values'],
+ *   '#entity_type' => The name of the entity type,
+ *   '#bundle' => The name of the bundle,
+ *   // One sub-array per field appearing in the entity, keyed by field name.
+ *   // The structure of the array differs slightly depending on whether the
+ *   // widget is 'single-value' (provides the input for one field value,
+ *   // most common case), and will therefore be repeated as many times as
+ *   // needed, or 'multiple-values' (one single widget allows the input of
+ *   // several values, e.g checkboxes, select box...).
+ *   // The sub-array is nested into a $langcode key where $langcode has the
+ *   // same value of the $langcode parameter above.
+ *   // The '#language' key holds the same value of $langcode and it is used
+ *   // to access the field sub-array when $langcode is unknown.
+ *   'field_foo' => array(
+ *     '#tree' => TRUE,
+ *     '#field_name' => The name of the field,
+ *     '#language' => $langcode,
+ *     $langcode => array(
+ *       '#field_name' => The name of the field,
+ *       '#language' => $langcode,
+ *       '#field_parents' => The 'parents' space for the field in the form,
+ *          equal to the #parents property of the $form parameter received by
+ *          field_attach_form(),
+ *       '#required' => Whether or not the field is required,
+ *       '#title' => The label of the field instance,
+ *       '#description' => The description text for the field instance,
+ *
+ *       // Only for 'single' widgets:
+ *       '#theme' => 'field_multiple_value_form',
+ *       '#cardinality' => The field cardinality,
+ *       // One sub-array per copy of the widget, keyed by delta.
+ *       0 => array(
+ *         '#entity_type' => The name of the entity type,
+ *         '#bundle' => The name of the bundle,
+ *         '#field_name' => The name of the field,
+ *         '#field_parents' => The 'parents' space for the field in the form,
+ *            equal to the #parents property of the $form parameter received by
+ *            field_attach_form(),
+ *         '#title' => The title to be displayed by the widget,
+ *         '#default_value' => The field value for delta 0,
+ *         '#required' => Whether the widget should be marked required,
+ *         '#delta' => 0,
+ *         '#columns' => The array of field columns,
+ *         // The remaining elements in the sub-array depend on the widget.
+ *         '#type' => The type of the widget,
+ *         ...
+ *       ),
+ *       1 => array(
+ *         ...
+ *       ),
+ *
+ *       // Only for multiple widgets:
+ *       '#entity_type' => The name of the entity type,
+ *       '#bundle' => $instance['bundle'],
+ *       '#columns'  => array_keys($field['columns']),
+ *       // The remaining elements in the sub-array depend on the widget.
+ *       '#type' => The type of the widget,
+ *       ...
+ *     ),
+ *     ...
+ *   ),
+ * )
+ * @endcode
+ *
+ * Additionally, some processing data is placed in $form_state, and can be
+ * accessed by field_form_get_state() and field_form_set_state().
+ *
+ * @param $entity_type
+ *   The type of $entity; e.g. 'node' or 'user'.
+ * @param $entity
+ *   The entity for which to load form elements, used to initialize
+ *   default form values.
+ * @param $form
+ *   The form structure to fill in. This can be a full form structure, or a
+ *   sub-element of a larger form. The #parents property can be set to control
+ *   the location of submitted field values within $form_state['values']. If
+ *   not specified, $form['#parents'] is set to an empty array, placing field
+ *   values at the top-level of $form_state['values'].
+ * @param $form_state
+ *   An associative array containing the current state of the form.
+ * @param $langcode
+ *   The language the field values are going to be entered, if no language
+ *   is provided the default site language will be used.
+ * @param array $options
+ *   An associative array of additional options. See _field_invoke() for
+ *   details.
+ *
+ * @see field_form_get_state()
+ * @see field_form_set_state()
+ */
+function field_attach_form($entity_type, $entity, &$form, &$form_state, $langcode = NULL, $options = array()) {
+  // Validate $options since this is a new parameter added after Drupal 7 was
+  // released.
+  $options = is_array($options) ? $options : array();
+
+  // Set #parents to 'top-level' by default.
+  $form += array('#parents' => array());
+
+  // If no language is provided use the default site language.
+  $options['language'] = field_valid_language($langcode);
+  $form += (array) _field_invoke_default('form', $entity_type, $entity, $form, $form_state, $options);
+
+  // Add custom weight handling.
+  list($id, $vid, $bundle) = entity_extract_ids($entity_type, $entity);
+  $form['#pre_render'][] = '_field_extra_fields_pre_render';
+  $form['#entity_type'] = $entity_type;
+  $form['#bundle'] = $bundle;
+
+  // Let other modules make changes to the form.
+  // Avoid module_invoke_all() to let parameters be taken by reference.
+  foreach (module_implements('field_attach_form') as $module) {
+    $function = $module . '_field_attach_form';
+    $function($entity_type, $entity, $form, $form_state, $langcode);
+  }
+}
+
+/**
+ * Loads fields for the current revisions of a group of entities.
+ *
+ * Loads all fields for each entity object in a group of a single entity type.
+ * The loaded field values are added directly to the entity objects.
+ *
+ * field_attach_load() is automatically called by the default entity controller
+ * class, and thus, in most cases, doesn't need to be explicitly called by the
+ * entity type module.
+ *
+ * @param $entity_type
+ *   The type of $entity; e.g., 'node' or 'user'.
+ * @param $entities
+ *   An array of entities for which to load fields, keyed by entity ID.
+ *   Each entity needs to have its 'bundle', 'id' and (if applicable)
+ *   'revision' keys filled in. The function adds the loaded field data
+ *   directly in the entity objects of the $entities array.
+ * @param $age
+ *   FIELD_LOAD_CURRENT to load the most recent revision for all
+ *   fields, or FIELD_LOAD_REVISION to load the version indicated by
+ *   each entity. Defaults to FIELD_LOAD_CURRENT; use
+ *   field_attach_load_revision() instead of passing FIELD_LOAD_REVISION.
+ * @param $options
+ *   An associative array of additional options, with the following keys:
+ *   - 'field_id': The field ID that should be loaded, instead of
+ *     loading all fields, for each entity. Note that returned entities
+ *     may contain data for other fields, for example if they are read
+ *     from a cache.
+ *   - 'deleted': If TRUE, the function will operate on deleted fields
+ *     as well as non-deleted fields. If unset or FALSE, only
+ *     non-deleted fields are operated on.
+ */
+function field_attach_load($entity_type, $entities, $age = FIELD_LOAD_CURRENT, $options = array()) {
+  $load_current = $age == FIELD_LOAD_CURRENT;
+
+  // Merge default options.
+  $default_options = array(
+    'deleted' => FALSE,
+  );
+  $options += $default_options;
+
+  $info = entity_get_info($entity_type);
+  // Only the most current revision of non-deleted fields for cacheable entity
+  // types can be cached.
+  $cache_read = $load_current && $info['field cache'] && empty($options['deleted']);
+  // In addition, do not write to the cache when loading a single field.
+  $cache_write = $cache_read && !isset($options['field_id']);
+
+  if (empty($entities)) {
+    return;
+  }
+
+  // Assume all entities will need to be queried. Entities found in the cache
+  // will be removed from the list.
+  $queried_entities = $entities;
+
+  // Fetch available entities from cache, if applicable.
+  if ($cache_read) {
+    // Build the list of cache entries to retrieve.
+    $cids = array();
+    foreach ($entities as $id => $entity) {
+      $cids[] = "field:$entity_type:$id";
+    }
+    $cache = cache_get_multiple($cids, 'cache_field');
+    // Put the cached field values back into the entities and remove them from
+    // the list of entities to query.
+    foreach ($entities as $id => $entity) {
+      $cid = "field:$entity_type:$id";
+      if (isset($cache[$cid])) {
+        unset($queried_entities[$id]);
+        foreach ($cache[$cid]->data as $field_name => $values) {
+          $entity->$field_name = $values;
+        }
+      }
+    }
+  }
+
+  // Fetch other entities from their storage location.
+  if ($queried_entities) {
+    // The invoke order is:
+    // - hook_field_storage_pre_load()
+    // - storage backend's hook_field_storage_load()
+    // - field-type module's hook_field_load()
+    // - hook_field_attach_load()
+
+    // Invoke hook_field_storage_pre_load(): let any module load field
+    // data before the storage engine, accumulating along the way.
+    $skip_fields = array();
+    foreach (module_implements('field_storage_pre_load') as $module) {
+      $function = $module . '_field_storage_pre_load';
+      $function($entity_type, $queried_entities, $age, $skip_fields, $options);
+    }
+
+    $instances = array();
+
+    // Collect the storage backends used by the remaining fields in the entities.
+    $storages = array();
+    foreach ($queried_entities as $entity) {
+      list($id, $vid, $bundle) = entity_extract_ids($entity_type, $entity);
+      $instances = _field_invoke_get_instances($entity_type, $bundle, $options);
+
+      foreach ($instances as $instance) {
+        $field_name = $instance['field_name'];
+        $field_id = $instance['field_id'];
+        // Make sure all fields are present at least as empty arrays.
+        if (!isset($queried_entities[$id]->{$field_name})) {
+          $queried_entities[$id]->{$field_name} = array();
+        }
+        // Collect the storage backend if the field has not been loaded yet.
+        if (!isset($skip_fields[$field_id])) {
+          $field = field_info_field_by_id($field_id);
+          $storages[$field['storage']['type']][$field_id][] = $load_current ? $id : $vid;
+        }
+      }
+    }
+
+    // Invoke hook_field_storage_load() on the relevant storage backends.
+    foreach ($storages as $storage => $fields) {
+      $storage_info = field_info_storage_types($storage);
+      module_invoke($storage_info['module'], 'field_storage_load', $entity_type, $queried_entities, $age, $fields, $options);
+    }
+
+    // Invoke field-type module's hook_field_load().
+    $null = NULL;
+    _field_invoke_multiple('load', $entity_type, $queried_entities, $age, $null, $options);
+
+    // Invoke hook_field_attach_load(): let other modules act on loading the
+    // entity.
+    module_invoke_all('field_attach_load', $entity_type, $queried_entities, $age, $options);
+
+    // Build cache data.
+    if ($cache_write) {
+      foreach ($queried_entities as $id => $entity) {
+        $data = array();
+        list($id, $vid, $bundle) = entity_extract_ids($entity_type, $entity);
+        $instances = field_info_instances($entity_type, $bundle);
+        foreach ($instances as $instance) {
+          $data[$instance['field_name']] = $queried_entities[$id]->{$instance['field_name']};
+        }
+        $cid = "field:$entity_type:$id";
+        cache_set($cid, $data, 'cache_field');
+      }
+    }
+  }
+}
+
+/**
+ * Load all fields for previous versions of a group of entities.
+ *
+ * Loading different versions of the same entities is not supported, and should
+ * be done by separate calls to the function.
+ *
+ * field_attach_load_revision() is automatically called by the default entity
+ * controller class, and thus, in most cases, doesn't need to be explicitly
+ * called by the entity type module.
+ *
+ * @param $entity_type
+ *   The type of $entity; e.g. 'node' or 'user'.
+ * @param $entities
+ *   An array of entities for which to load fields, keyed by entity ID. Each
+ *   entity needs to have its 'bundle', 'id' and (if applicable) 'revision'
+ *   keys filled. The function adds the loaded field data directly in the
+ *   entity objects of the $entities array.
+ * @param $options
+ *   An associative array of additional options. See field_attach_load() for
+ *   details.
+ */
+function field_attach_load_revision($entity_type, $entities, $options = array()) {
+  return field_attach_load($entity_type, $entities, FIELD_LOAD_REVISION, $options);
+}
+
+/**
+ * Perform field validation against the field data in an entity.
+ *
+ * This function does not perform field widget validation on form
+ * submissions. It is intended to be called during API save
+ * operations. Use field_attach_form_validate() to validate form
+ * submissions.
+ *
+ * @param $entity_type
+ *   The type of $entity; e.g. 'node' or 'user'.
+ * @param $entity
+ *   The entity with fields to validate.
+ * @throws FieldValidationException
+ *   If validation errors are found, a FieldValidationException is thrown. The
+ *   'errors' property contains the array of errors, keyed by field name,
+ *   language and delta.
+ * @param array $options
+ *   An associative array of additional options. See _field_invoke() for
+ *   details.
+ */
+function field_attach_validate($entity_type, $entity, $options = array()) {
+  // Validate $options since this is a new parameter added after Drupal 7 was
+  // released.
+  $options = is_array($options) ? $options : array();
+
+  $errors = array();
+  // Check generic, field-type-agnostic errors first.
+  $null = NULL;
+  _field_invoke_default('validate', $entity_type, $entity, $errors, $null, $options);
+  // Check field-type specific errors.
+  _field_invoke('validate', $entity_type, $entity, $errors, $null, $options);
+
+  // Let other modules validate the entity.
+  // Avoid module_invoke_all() to let $errors be taken by reference.
+  foreach (module_implements('field_attach_validate') as $module) {
+    $function = $module . '_field_attach_validate';
+    $function($entity_type, $entity, $errors);
+  }
+
+  if ($errors) {
+    throw new FieldValidationException($errors);
+  }
+}
+
+/**
+ * Perform field validation against form-submitted field values.
+ *
+ * There are two levels of validation for fields in forms: widget
+ * validation, and field validation.
+ * - Widget validation steps are specific to a given widget's own form
+ *   structure and UI metaphors. They are executed through FAPI's
+ *   #element_validate property during normal form validation.
+ * - Field validation steps are common to a given field type, independently of
+ *   the specific widget being used in a given form. They are defined in the
+ *   field type's implementation of hook_field_validate().
+ *
+ * This function performs field validation in the context of a form
+ * submission. It converts field validation errors into form errors
+ * on the correct form elements. Fieldable entity types should call
+ * this function during their own form validation function.
+ *
+ * @param $entity_type
+ *   The type of $entity; e.g. 'node' or 'user'.
+ * @param $entity
+ *   The entity being submitted. The 'bundle', 'id' and (if applicable)
+ *   'revision' keys should be present. The actual field values will be read
+ *   from $form_state['values'].
+ * @param $form
+ *   The form structure where field elements are attached to. This might be a
+ *   full form structure, or a sub-element of a larger form.
+ * @param $form_state
+ *   An associative array containing the current state of the form.
+ * @param array $options
+ *   An associative array of additional options. See _field_invoke() for
+ *   details.
+ */
+function field_attach_form_validate($entity_type, $entity, $form, &$form_state, $options = array()) {
+  // Validate $options since this is a new parameter added after Drupal 7 was
+  // released.
+  $options = is_array($options) ? $options : array();
+
+  // Extract field values from submitted values.
+  _field_invoke_default('extract_form_values', $entity_type, $entity, $form, $form_state);
+
+  // Perform field_level validation.
+  try {
+    field_attach_validate($entity_type, $entity, $options);
+  }
+  catch (FieldValidationException $e) {
+    // Pass field-level validation errors back to widgets for accurate error
+    // flagging.
+    foreach ($e->errors as $field_name => $field_errors) {
+      foreach ($field_errors as $langcode => $errors) {
+        $field_state = field_form_get_state($form['#parents'], $field_name, $langcode, $form_state);
+        $field_state['errors'] = $errors;
+        field_form_set_state($form['#parents'], $field_name, $langcode, $form_state, $field_state);
+      }
+    }
+    _field_invoke_default('form_errors', $entity_type, $entity, $form, $form_state, $options);
+  }
+}
+
+/**
+ * Perform necessary operations on field data submitted by a form.
+ *
+ * Currently, this accounts for drag-and-drop reordering of
+ * field values, and filtering of empty values.
+ *
+ * @param $entity_type
+ *   The type of $entity; e.g. 'node' or 'user'.
+ * @param $entity
+ *   The entity being submitted. The 'bundle', 'id' and (if applicable)
+ *   'revision' keys should be present. The actual field values will be read
+ *   from $form_state['values'].
+ * @param $form
+ *   The form structure where field elements are attached to. This might be a
+ *   full form structure, or a sub-element of a larger form.
+ * @param $form_state
+ *   An associative array containing the current state of the form.
+ * @param array $options
+ *   An associative array of additional options. See _field_invoke() for
+ *   details.
+ */
+function field_attach_submit($entity_type, $entity, $form, &$form_state, $options = array()) {
+  // Validate $options since this is a new parameter added after Drupal 7 was
+  // released.
+  $options = is_array($options) ? $options : array();
+
+  // Extract field values from submitted values.
+  _field_invoke_default('extract_form_values', $entity_type, $entity, $form, $form_state, $options);
+
+  _field_invoke_default('submit', $entity_type, $entity, $form, $form_state, $options);
+
+  // Let other modules act on submitting the entity.
+  // Avoid module_invoke_all() to let $form_state be taken by reference.
+  foreach (module_implements('field_attach_submit') as $module) {
+    $function = $module . '_field_attach_submit';
+    $function($entity_type, $entity, $form, $form_state);
+  }
+}
+
+/**
+ * Perform necessary operations just before fields data get saved.
+ *
+ * We take no specific action here, we just give other
+ * modules the opportunity to act.
+ *
+ * @param $entity_type
+ *   The type of $entity; e.g. 'node' or 'user'.
+ * @param $entity
+ *   The entity with fields to process.
+ */
+function field_attach_presave($entity_type, $entity) {
+  _field_invoke('presave', $entity_type, $entity);
+
+  // Let other modules act on presaving the entity.
+  module_invoke_all('field_attach_presave', $entity_type, $entity);
+}
+
+/**
+ * Save field data for a new entity.
+ *
+ * The passed-in entity must already contain its id and (if applicable)
+ * revision id attributes.
+ * Default values (if any) will be saved for fields not present in the
+ * $entity.
+ *
+ * @param $entity_type
+ *   The type of $entity; e.g. 'node' or 'user'.
+ * @param $entity
+ *   The entity with fields to save.
+ * @return
+ *   Default values (if any) will be added to the $entity parameter for fields
+ *   it leaves unspecified.
+ */
+function field_attach_insert($entity_type, $entity) {
+  _field_invoke_default('insert', $entity_type, $entity);
+  _field_invoke('insert', $entity_type, $entity);
+
+  list($id, $vid, $bundle) = entity_extract_ids($entity_type, $entity);
+
+  // Let any module insert field data before the storage engine, accumulating
+  // saved fields along the way.
+  $skip_fields = array();
+  foreach (module_implements('field_storage_pre_insert') as $module) {
+    $function = $module . '_field_storage_pre_insert';
+    $function($entity_type, $entity, $skip_fields);
+  }
+
+  // Collect the storage backends used by the remaining fields in the entities.
+  $storages = array();
+  foreach (field_info_instances($entity_type, $bundle) as $instance) {
+    $field = field_info_field_by_id($instance['field_id']);
+    $field_id = $field['id'];
+    $field_name = $field['field_name'];
+    if (!empty($entity->$field_name)) {
+      // Collect the storage backend if the field has not been written yet.
+      if (!isset($skip_fields[$field_id])) {
+        $storages[$field['storage']['type']][$field_id] = $field_id;
+      }
+    }
+  }
+
+  // Field storage backends save any remaining unsaved fields.
+  foreach ($storages as $storage => $fields) {
+    $storage_info = field_info_storage_types($storage);
+    module_invoke($storage_info['module'], 'field_storage_write', $entity_type, $entity, FIELD_STORAGE_INSERT, $fields);
+  }
+
+  // Let other modules act on inserting the entity.
+  module_invoke_all('field_attach_insert', $entity_type, $entity);
+
+  $entity_info = entity_get_info($entity_type);
+}
+
+/**
+ * Save field data for an existing entity.
+ *
+ * When calling this function outside an entity save operation be sure to
+ * clear caches for the entity:
+ * @code
+ * entity_get_controller($entity_type)->resetCache(array($entity_id))
+ * @endcode
+ *
+ * @param $entity_type
+ *   The type of $entity; e.g. 'node' or 'user'.
+ * @param $entity
+ *   The entity with fields to save.
+ */
+function field_attach_update($entity_type, $entity) {
+  _field_invoke('update', $entity_type, $entity);
+
+  list($id, $vid, $bundle) = entity_extract_ids($entity_type, $entity);
+
+  // Let any module update field data before the storage engine, accumulating
+  // saved fields along the way.
+  $skip_fields = array();
+  foreach (module_implements('field_storage_pre_update') as $module) {
+    $function = $module . '_field_storage_pre_update';
+    $function($entity_type, $entity, $skip_fields);
+  }
+
+  // Collect the storage backends used by the remaining fields in the entities.
+  $storages = array();
+  foreach (field_info_instances($entity_type, $bundle) as $instance) {
+    $field = field_info_field_by_id($instance['field_id']);
+    $field_id = $field['id'];
+    $field_name = $field['field_name'];
+    // Leave the field untouched if $entity comes with no $field_name property,
+    // but empty the field if it comes as a NULL value or an empty array.
+    // Function property_exists() is slower, so we catch the more frequent
+    // cases where it's an empty array with the faster isset().
+    if (isset($entity->$field_name) || property_exists($entity, $field_name)) {
+      // Collect the storage backend if the field has not been written yet.
+      if (!isset($skip_fields[$field_id])) {
+        $storages[$field['storage']['type']][$field_id] = $field_id;
+      }
+    }
+  }
+
+  // Field storage backends save any remaining unsaved fields.
+  foreach ($storages as $storage => $fields) {
+    $storage_info = field_info_storage_types($storage);
+    module_invoke($storage_info['module'], 'field_storage_write', $entity_type, $entity, FIELD_STORAGE_UPDATE, $fields);
+  }
+
+  // Let other modules act on updating the entity.
+  module_invoke_all('field_attach_update', $entity_type, $entity);
+
+  $entity_info = entity_get_info($entity_type);
+  if ($entity_info['field cache']) {
+    cache_clear_all("field:$entity_type:$id", 'cache_field');
+  }
+}
+
+/**
+ * Delete field data for an existing entity. This deletes all
+ * revisions of field data for the entity.
+ *
+ * @param $entity_type
+ *   The type of $entity; e.g. 'node' or 'user'.
+ * @param $entity
+ *   The entity whose field data to delete.
+ */
+function field_attach_delete($entity_type, $entity) {
+  _field_invoke('delete', $entity_type, $entity);
+
+  list($id, $vid, $bundle) = entity_extract_ids($entity_type, $entity);
+
+  // Collect the storage backends used by the fields in the entities.
+  $storages = array();
+  foreach (field_info_instances($entity_type, $bundle) as $instance) {
+    $field = field_info_field_by_id($instance['field_id']);
+    $field_id = $field['id'];
+    $storages[$field['storage']['type']][$field_id] = $field_id;
+  }
+
+  // Field storage backends delete their data.
+  foreach ($storages as $storage => $fields) {
+    $storage_info = field_info_storage_types($storage);
+    module_invoke($storage_info['module'], 'field_storage_delete', $entity_type, $entity, $fields);
+  }
+
+  // Let other modules act on deleting the entity.
+  module_invoke_all('field_attach_delete', $entity_type, $entity);
+
+  $entity_info = entity_get_info($entity_type);
+  if ($entity_info['field cache']) {
+    cache_clear_all("field:$entity_type:$id", 'cache_field');
+  }
+}
+
+/**
+ * Delete field data for a single revision of an existing entity. The
+ * passed entity must have a revision id attribute.
+ *
+ * @param $entity_type
+ *   The type of $entity; e.g. 'node' or 'user'.
+ * @param $entity
+ *   The entity with fields to save.
+ */
+function field_attach_delete_revision($entity_type, $entity) {
+  _field_invoke('delete_revision', $entity_type, $entity);
+
+  list($id, $vid, $bundle) = entity_extract_ids($entity_type, $entity);
+
+  // Collect the storage backends used by the fields in the entities.
+  $storages = array();
+  foreach (field_info_instances($entity_type, $bundle) as $instance) {
+    $field = field_info_field_by_id($instance['field_id']);
+    $field_id = $field['id'];
+    $storages[$field['storage']['type']][$field_id] = $field_id;
+  }
+
+  // Field storage backends delete their data.
+  foreach ($storages as $storage => $fields) {
+    $storage_info = field_info_storage_types($storage);
+    module_invoke($storage_info['module'], 'field_storage_delete_revision', $entity_type, $entity, $fields);
+  }
+
+  // Let other modules act on deleting the revision.
+  module_invoke_all('field_attach_delete_revision', $entity_type, $entity);
+}
+
+/**
+ * Prepare field data prior to display.
+ *
+ * This function lets field types and formatters load additional data
+ * needed for display that is not automatically loaded during
+ * field_attach_load(). It accepts an array of entities to allow query
+ * optimisation when displaying lists of entities.
+ *
+ * field_attach_prepare_view() and field_attach_view() are two halves
+ * of the same operation. It is safe to call
+ * field_attach_prepare_view() multiple times on the same entity
+ * before calling field_attach_view() on it, but calling any Field
+ * API operation on an entity between passing that entity to these two
+ * functions may yield incorrect results.
+ *
+ * @param $entity_type
+ *   The type of $entities; e.g. 'node' or 'user'.
+ * @param $entities
+ *   An array of entities, keyed by entity id.
+ * @param $view_mode
+ *   View mode, e.g. 'full', 'teaser'...
+ * @param $langcode
+ *   (Optional) The language the field values are to be shown in. If no language
+ *   is provided the current language is used.
+ * @param array $options
+ *   An associative array of additional options. See _field_invoke() for
+ *   details.
+ */
+function field_attach_prepare_view($entity_type, $entities, $view_mode, $langcode = NULL, $options = array()) {
+  // Validate $options since this is a new parameter added after Drupal 7 was
+  // released.
+  $options = is_array($options) ? $options : array();
+
+  $options['language'] = array();
+
+  // To ensure hooks are only run once per entity, only process items without
+  // the _field_view_prepared flag.
+  // @todo: resolve this more generally for both entity and field level hooks.
+  $prepare = array();
+  foreach ($entities as $id => $entity) {
+    if (empty($entity->_field_view_prepared)) {
+      // Add this entity to the items to be prepared.
+      $prepare[$id] = $entity;
+
+      // Determine the actual language to display for each field, given the
+      // languages available in the field data.
+      $options['language'][$id] = field_language($entity_type, $entity, NULL, $langcode);
+
+      // Mark this item as prepared.
+      $entity->_field_view_prepared = TRUE;
+    }
+  }
+
+  $null = NULL;
+  // First let the field types do their preparation.
+  _field_invoke_multiple('prepare_view', $entity_type, $prepare, $null, $null, $options);
+  // Then let the formatters do their own specific massaging.
+  // field_default_prepare_view() takes care of dispatching to the correct
+  // formatters according to the display settings for the view mode.
+  _field_invoke_multiple_default('prepare_view', $entity_type, $prepare, $view_mode, $null, $options);
+}
+
+/**
+ * Returns a renderable array for the fields on an entity.
+ *
+ * Each field is displayed according to the display options specified in the
+ * $instance definition for the given $view_mode.
+ *
+ * field_attach_prepare_view() and field_attach_view() are two halves
+ * of the same operation. It is safe to call
+ * field_attach_prepare_view() multiple times on the same entity
+ * before calling field_attach_view() on it, but calling any Field
+ * API operation on an entity between passing that entity to these two
+ * functions may yield incorrect results.
+ *
+ * Sample structure:
+ * @code
+ * array(
+ *   'field_foo' => array(
+ *     '#theme' => 'field',
+ *     '#title' => the label of the field instance,
+ *     '#label_display' => the label display mode,
+ *     '#object' => the fieldable entity being displayed,
+ *     '#entity_type' => the type of the entity being displayed,
+ *     '#language' => the language of the field values being displayed,
+ *     '#view_mode' => the view mode,
+ *     '#field_name' => the name of the field,
+ *     '#field_type' => the type of the field,
+ *     '#formatter' => the name of the formatter,
+ *     '#items' => the field values being displayed,
+ *     // The element's children are the formatted values returned by
+ *     // hook_field_formatter_view().
+ *   ),
+ * );
+ * @endcode
+ *
+ * @param $entity_type
+ *   The type of $entity; e.g. 'node' or 'user'.
+ * @param $entity
+ *   The entity with fields to render.
+ * @param $view_mode
+ *   View mode, e.g. 'full', 'teaser'...
+ * @param $langcode
+ *   The language the field values are to be shown in. If no language is
+ *   provided the current language is used.
+ * @param array $options
+ *   An associative array of additional options. See _field_invoke() for
+ *   details.
+ * @return
+ *   A renderable array for the field values.
+ */
+function field_attach_view($entity_type, $entity, $view_mode, $langcode = NULL, $options = array()) {
+  // Validate $options since this is a new parameter added after Drupal 7 was
+  // released.
+  $options = is_array($options) ? $options : array();
+
+  // Determine the actual language to display for each field, given the
+  // languages available in the field data.
+  $display_language = field_language($entity_type, $entity, NULL, $langcode);
+  $options['language'] = $display_language;
+
+  // Invoke field_default_view().
+  $null = NULL;
+  $output = _field_invoke_default('view', $entity_type, $entity, $view_mode, $null, $options);
+
+  // Add custom weight handling.
+  list($id, $vid, $bundle) = entity_extract_ids($entity_type, $entity);
+  $output['#pre_render'][] = '_field_extra_fields_pre_render';
+  $output['#entity_type'] = $entity_type;
+  $output['#bundle'] = $bundle;
+
+  // Let other modules alter the renderable array.
+  $context = array(
+    'entity_type' => $entity_type,
+    'entity' => $entity,
+    'view_mode' => $view_mode,
+    'display' => $view_mode,
+    'language' => $langcode,
+  );
+  drupal_alter('field_attach_view', $output, $context);
+
+  // Reset the _field_view_prepared flag set in field_attach_prepare_view(),
+  // in case the same entity is displayed with different settings later in
+  // the request.
+  unset($entity->_field_view_prepared);
+
+  return $output;
+}
+
+/**
+ * Populate the template variables with the field values available for rendering.
+ *
+ * The $variables array will be populated with all the field instance values
+ * associated with the given entity type, keyed by field name; in case of
+ * translatable fields the language currently chosen for display will be
+ * selected.
+ *
+ * @param $entity_type
+ *   The type of $entity; e.g. 'node' or 'user'.
+ * @param $entity
+ *   The entity with fields to render.
+ * @param $element
+ *   The structured array containing the values ready for rendering.
+ * @param $variables
+ *   The variables array is passed by reference and will be populated with field
+ *   values.
+ */
+function field_attach_preprocess($entity_type, $entity, $element, &$variables) {
+  list(, , $bundle) = entity_extract_ids($entity_type, $entity);
+
+  foreach (field_info_instances($entity_type, $bundle) as $instance) {
+    $field_name = $instance['field_name'];
+    if (isset($element[$field_name]['#language'])) {
+      $langcode = $element[$field_name]['#language'];
+      $variables[$field_name] = isset($entity->{$field_name}[$langcode]) ? $entity->{$field_name}[$langcode] : NULL;
+    }
+  }
+
+  // Let other modules make changes to the $variables array.
+  $context = array(
+    'entity_type' => $entity_type,
+    'entity' => $entity,
+    'element' => $element,
+  );
+  drupal_alter('field_attach_preprocess', $variables, $context);
+}
+
+/**
+ * Prepares an entity for translation.
+ *
+ * This function is used to fill-in the form default values for Field API fields
+ * while performing entity translation. By default it copies all the source
+ * values in the given source language to the new entity and assigns them the
+ * target language.
+ *
+ * This is used as part of the 'per entity' translation pattern, which is
+ * implemented only for nodes by translation.module. Other entity types may be
+ * supported through contributed modules.
+ *
+ * @param $entity_type
+ *   The type of $entity; e.g. 'node' or 'user'.
+ * @param $entity
+ *   The entity to be prepared for translation.
+ * @param $langcode
+ *   The language the entity has to be translated in.
+ * @param $source_entity
+ *   The source entity holding the field values to be translated.
+ * @param $source_langcode
+ *   The source language from which translate.
+ */
+function field_attach_prepare_translation($entity_type, $entity, $langcode, $source_entity, $source_langcode) {
+  $options = array('language' => $langcode);
+  // Copy source field values into the entity to be prepared.
+  _field_invoke_default('prepare_translation', $entity_type, $entity, $source_entity, $source_langcode, $options);
+  // Let field types handle their own advanced translation pattern if needed.
+  _field_invoke('prepare_translation', $entity_type, $entity, $source_entity, $source_langcode, $options);
+  // Let other modules alter the entity translation.
+  $context = array(
+    'entity_type' => $entity_type,
+    'langcode' => $langcode,
+    'source_entity' => $source_entity,
+    'source_langcode' => $source_langcode,
+  );
+  drupal_alter('field_attach_prepare_translation', $entity, $context);
+}
+
+/**
+ * Notify field.module that a new bundle was created.
+ *
+ * The default SQL-based storage doesn't need to do anything about it, but
+ * others might.
+ *
+ * @param $entity_type
+ *   The entity type to which the bundle is bound.
+ * @param $bundle
+ *   The name of the newly created bundle.
+ */
+function field_attach_create_bundle($entity_type, $bundle) {
+  // Clear the cache.
+  field_cache_clear();
+
+  // Let other modules act on creating the bundle.
+  module_invoke_all('field_attach_create_bundle', $entity_type, $bundle);
+}
+
+/**
+ * Notify field.module that a bundle was renamed.
+ *
+ * @param $entity_type
+ *   The entity type to which the bundle is bound.
+ * @param $bundle_old
+ *   The previous name of the bundle.
+ * @param $bundle_new
+ *   The new name of the bundle.
+ */
+function field_attach_rename_bundle($entity_type, $bundle_old, $bundle_new) {
+  db_update('field_config_instance')
+    ->fields(array('bundle' => $bundle_new))
+    ->condition('entity_type', $entity_type)
+    ->condition('bundle', $bundle_old)
+    ->execute();
+
+  // Clear the cache.
+  field_cache_clear();
+
+  // Update bundle settings.
+  $settings = variable_get('field_bundle_settings_' . $entity_type . '__' . $bundle_old, array());
+  variable_set('field_bundle_settings_' . $entity_type . '__' . $bundle_new, $settings);
+  variable_del('field_bundle_settings_' . $entity_type . '__' . $bundle_old);
+
+  // Let other modules act on renaming the bundle.
+  module_invoke_all('field_attach_rename_bundle', $entity_type, $bundle_old, $bundle_new);
+}
+
+/**
+ * Notify field.module the a bundle was deleted.
+ *
+ * This deletes the data for the field instances as well as the field instances
+ * themselves. This function actually just marks the data and field instances
+ * and deleted, leaving the garbage collection for a separate process, because
+ * it is not always possible to delete this much data in a single page request
+ * (particularly since for some field types, the deletion is more than just a
+ * simple DELETE query).
+ *
+ * @param $entity_type
+ *   The entity type to which the bundle is bound.
+ * @param $bundle
+ *   The bundle to delete.
+ */
+function field_attach_delete_bundle($entity_type, $bundle) {
+  // First, delete the instances themselves. field_read_instances() must be
+  // used here since field_info_instances() does not return instances for
+  // disabled entity types or bundles.
+  $instances = field_read_instances(array('entity_type' => $entity_type, 'bundle' => $bundle), array('include_inactive' => 1));
+  foreach ($instances as $instance) {
+    field_delete_instance($instance);
+  }
+
+  // Clear the cache.
+  field_cache_clear();
+
+  // Clear bundle display settings.
+  variable_del('field_bundle_settings_' . $entity_type . '__' . $bundle);
+
+  // Let other modules act on deleting the bundle.
+  module_invoke_all('field_attach_delete_bundle', $entity_type, $bundle, $instances);
+}
+
+
+/**
+ * @} End of "defgroup field_attach".
+ */