corpus_parole: comparison cms/drupal/modules/field/field.crud.inc

equal deleted inserted replaced

-:07239de796bb
+:e756a8c72c3d
+<?php
+/**
+* @file
+* Field CRUD API, handling field and field instance creation and deletion.
+*/
+/**
+* @defgroup field_crud Field CRUD API
+* @{
+* Create, update, and delete Field API fields, bundles, and instances.
+*
+* Modules use this API, often in hook_install(), to create custom
+* data structures. UI modules will use it to create a user interface.
+*
+* The Field CRUD API uses
+* @link field Field API data structures @endlink.
+*
+* See @link field Field API @endlink for information about the other parts of
+* the Field API.
+*/
+/**
+* Creates a field.
+*
+* This function does not bind the field to any bundle; use
+* field_create_instance() for that.
+*
+* @param $field
+*   A field definition array. The field_name and type properties are required.
+*   Other properties, if omitted, will be given the following default values:
+*   - cardinality: 1
+*   - locked: FALSE
+*   - indexes: the field-type indexes, specified by the field type's
+*     hook_field_schema(). The indexes specified in $field are added
+*     to those default indexes. It is possible to override the
+*     definition of a field-type index by providing an index with the
+*     same name, or to remove it by redefining it as an empty array
+*     of columns. Overriding field-type indexes should be done
+*     carefully, for it might seriously affect the site's performance.
+*   - settings: each omitted setting is given the default value defined in
+*     hook_field_info().
+*   - storage:
+*     - type: the storage backend specified in the 'field_storage_default'
+*       system variable.
+*     - settings: each omitted setting is given the default value specified in
+*       hook_field_storage_info().
+*
+* @return
+*   The $field array with the id property filled in.
+*
+* @throws FieldException
+*
+* See: @link field Field API data structures @endlink.
+*/
+function field_create_field($field) {
+// Field name is required.
+if (empty($field['field_name'])) {
+throw new FieldException('Attempt to create an unnamed field.');
+}
+// Field type is required.
+if (empty($field['type'])) {
+throw new FieldException(format_string('Attempt to create field @field_name with no type.', array('@field_name' => $field['field_name'])));
+}
+// Field name cannot contain invalid characters.
+if (!preg_match('/^[_a-z]+[_a-z0-9]*$/', $field['field_name'])) {
+throw new FieldException(format_string('Attempt to create a field @field_name with invalid characters. Only lowercase alphanumeric characters and underscores are allowed, and only lowercase letters and underscore are allowed as the first character', array('@field_name' => $field['field_name'])));
+}
+// Field name cannot be longer than 32 characters. We use drupal_strlen()
+// because the DB layer assumes that column widths are given in characters,
+// not bytes.
+if (drupal_strlen($field['field_name']) > 32) {
+throw new FieldException(t('Attempt to create a field with a name longer than 32 characters: %name',
+array('%name' => $field['field_name'])));
+}
+// Ensure the field name is unique over active and disabled fields.
+// We do not care about deleted fields.
+$prior_field = field_read_field($field['field_name'], array('include_inactive' => TRUE));
+if (!empty($prior_field)) {
+$message = $prior_field['active']?
+t('Attempt to create field name %name which already exists and is active.', array('%name' => $field['field_name'])):
+t('Attempt to create field name %name which already exists, although it is inactive.', array('%name' => $field['field_name']));
+throw new FieldException($message);
+}
+// Disallow reserved field names. This can't prevent all field name
+// collisions with existing entity properties, but some is better
+// than none.
+foreach (entity_get_info() as $type => $info) {
+if (in_array($field['field_name'], $info['entity keys'])) {
+throw new FieldException(t('Attempt to create field name %name which is reserved by entity type %type.', array('%name' => $field['field_name'], '%type' => $type)));
+}
+}
+$field += array(
+'entity_types' => array(),
+'cardinality' => 1,
+'translatable' => FALSE,
+'locked' => FALSE,
+'settings' => array(),
+'storage' => array(),
+'deleted' => 0,
+);
+// Check that the field type is known.
+$field_type = field_info_field_types($field['type']);
+if (!$field_type) {
+throw new FieldException(t('Attempt to create a field of unknown type %type.', array('%type' => $field['type'])));
+}
+// Create all per-field-type properties (needed here as long as we have
+// settings that impact column definitions).
+$field['settings'] += field_info_field_settings($field['type']);
+$field['module'] = $field_type['module'];
+$field['active'] = 1;
+// Provide default storage.
+$field['storage'] += array(
+'type' => variable_get('field_storage_default', 'field_sql_storage'),
+'settings' => array(),
+);
+// Check that the storage type is known.
+$storage_type = field_info_storage_types($field['storage']['type']);
+if (!$storage_type) {
+throw new FieldException(t('Attempt to create a field with unknown storage type %type.', array('%type' => $field['storage']['type'])));
+}
+// Provide default storage settings.
+$field['storage']['settings'] += field_info_storage_settings($field['storage']['type']);
+$field['storage']['module'] = $storage_type['module'];
+$field['storage']['active'] = 1;
+// Collect storage information.
+module_load_install($field['module']);
+$schema = (array) module_invoke($field['module'], 'field_schema', $field);
+$schema += array('columns' => array(), 'indexes' => array(), 'foreign keys' => array());
+// 'columns' are hardcoded in the field type.
+$field['columns'] = $schema['columns'];
+// 'foreign keys' are hardcoded in the field type.
+$field['foreign keys'] = $schema['foreign keys'];
+// 'indexes' can be both hardcoded in the field type, and specified in the
+// incoming $field definition.
+$field += array(
+'indexes' => array(),
+);
+$field['indexes'] += $schema['indexes'];
+// The serialized 'data' column contains everything from $field that does not
+// have its own column and is not automatically populated when the field is
+// read.
+$data = $field;
+unset($data['columns'], $data['field_name'], $data['type'], $data['active'], $data['module'], $data['storage_type'], $data['storage_active'], $data['storage_module'], $data['locked'], $data['cardinality'], $data['deleted']);
+// Additionally, do not save the 'bundles' property populated by
+// field_info_field().
+unset($data['bundles']);
+$record = array(
+'field_name' => $field['field_name'],
+'type' => $field['type'],
+'module' => $field['module'],
+'active' => $field['active'],
+'storage_type' => $field['storage']['type'],
+'storage_module' => $field['storage']['module'],
+'storage_active' => $field['storage']['active'],
+'locked' => $field['locked'],
+'data' => $data,
+'cardinality' => $field['cardinality'],
+'translatable' => $field['translatable'],
+'deleted' => $field['deleted'],
+);
+// Store the field and get the id back.
+drupal_write_record('field_config', $record);
+$field['id'] = $record['id'];
+// Invoke hook_field_storage_create_field after the field is
+// complete (e.g. it has its id).
+try {
+// Invoke hook_field_storage_create_field after
+// drupal_write_record() sets the field id.
+module_invoke($storage_type['module'], 'field_storage_create_field', $field);
+}
+catch (Exception $e) {
+// If storage creation failed, remove the field_config record before
+// rethrowing the exception.
+db_delete('field_config')
+->condition('id', $field['id'])
+->execute();
+throw $e;
+}
+// Clear caches
+field_cache_clear();
+// Invoke external hooks after the cache is cleared for API consistency.
+module_invoke_all('field_create_field', $field);
+return $field;
+}
+/**
+* Updates a field.
+*
+* Any module may forbid any update for any reason. For example, the
+* field's storage module might forbid an update if it would change
+* the storage schema while data for the field exists. A field type
+* module might forbid an update if it would change existing data's
+* semantics, or if there are external dependencies on field settings
+* that cannot be updated.
+*
+* @param $field
+*   A field structure. $field['field_name'] must provided; it
+*   identifies the field that will be updated to match this
+*   structure. Any other properties of the field that are not
+*   specified in $field will be left unchanged, so it is not
+*   necessary to pass in a fully populated $field structure.
+* @return
+*   Throws a FieldException if the update cannot be performed.
+* @see field_create_field()
+*/
+function field_update_field($field) {
+// Check that the specified field exists.
+$prior_field = field_read_field($field['field_name']);
+if (empty($prior_field)) {
+throw new FieldException('Attempt to update a non-existent field.');
+}
+// Use the prior field values for anything not specifically set by the new
+// field to be sure that all values are set.
+$field += $prior_field;
+$field['settings'] += $prior_field['settings'];
+// Some updates are always disallowed.
+if ($field['type'] != $prior_field['type']) {
+throw new FieldException("Cannot change an existing field's type.");
+}
+if ($field['entity_types'] != $prior_field['entity_types']) {
+throw new FieldException("Cannot change an existing field's entity_types property.");
+}
+if ($field['storage']['type'] != $prior_field['storage']['type']) {
+throw new FieldException("Cannot change an existing field's storage type.");
+}
+// Collect the new storage information, since what is in
+// $prior_field may no longer be right.
+module_load_install($field['module']);
+$schema = (array) module_invoke($field['module'], 'field_schema', $field);
+$schema += array('columns' => array(), 'indexes' => array(), 'foreign keys' => array());
+// 'columns' are hardcoded in the field type.
+$field['columns'] = $schema['columns'];
+// 'foreign keys' are hardcoded in the field type.
+$field['foreign keys'] = $schema['foreign keys'];
+// 'indexes' can be both hardcoded in the field type, and specified in the
+// incoming $field definition.
+$field += array(
+'indexes' => array(),
+);
+$field['indexes'] += $schema['indexes'];
+$has_data = field_has_data($field);
+// See if any module forbids the update by throwing an exception.
+foreach (module_implements('field_update_forbid') as $module) {
+$function = $module . '_field_update_forbid';
+$function($field, $prior_field, $has_data);
+}
+// Tell the storage engine to update the field. Do this before
+// saving the new definition since it still might fail.
+$storage_type = field_info_storage_types($field['storage']['type']);
+module_invoke($storage_type['module'], 'field_storage_update_field', $field, $prior_field, $has_data);
+// Save the new field definition. @todo: refactor with
+// field_create_field.
+// The serialized 'data' column contains everything from $field that does not
+// have its own column and is not automatically populated when the field is
+// read.
+$data = $field;
+unset($data['columns'], $data['field_name'], $data['type'], $data['locked'], $data['module'], $data['cardinality'], $data['active'], $data['deleted']);
+// Additionally, do not save the 'bundles' property populated by
+// field_info_field().
+unset($data['bundles']);
+$field['data'] = $data;
+// Store the field and create the id.
+$primary_key = array('id');
+drupal_write_record('field_config', $field, $primary_key);
+// Clear caches
+field_cache_clear();
+// Invoke external hooks after the cache is cleared for API consistency.
+module_invoke_all('field_update_field', $field, $prior_field, $has_data);
+}
+/**
+* Reads a single field record directly from the database.
+*
+* Generally, you should use the field_info_field() instead.
+*
+* This function will not return deleted fields. Use
+* field_read_fields() instead for this purpose.
+*
+* @param $field_name
+*   The field name to read.
+* @param array $include_additional
+*   The default behavior of this function is to not return a field that
+*   is inactive. Setting
+*   $include_additional['include_inactive'] to TRUE will override this
+*   behavior.
+* @return
+*   A field definition array, or FALSE.
+*/
+function field_read_field($field_name, $include_additional = array()) {
+$fields = field_read_fields(array('field_name' => $field_name), $include_additional);
+return $fields ? current($fields) : FALSE;
+}
+/**
+* Reads in fields that match an array of conditions.
+*
+* @param array $params
+*   An array of conditions to match against. Keys are columns from the
+*   'field_config' table, values are conditions to match. Additionally,
+*   conditions on the 'entity_type' and 'bundle' columns from the
+*   'field_config_instance' table are supported (select fields having an
+*   instance on a given bundle).
+* @param array $include_additional
+*   The default behavior of this function is to not return fields that
+*   are inactive or have been deleted. Setting
+*   $include_additional['include_inactive'] or
+*   $include_additional['include_deleted'] to TRUE will override this
+*   behavior.
+* @return
+*   An array of fields matching $params. If
+*   $include_additional['include_deleted'] is TRUE, the array is keyed
+*   by field id, otherwise it is keyed by field name.
+*/
+function field_read_fields($params = array(), $include_additional = array()) {
+$query = db_select('field_config', 'fc', array('fetch' => PDO::FETCH_ASSOC));
+$query->fields('fc');
+// Turn the conditions into a query.
+foreach ($params as $key => $value) {
+// Allow filtering on the 'entity_type' and 'bundle' columns of the
+// field_config_instance table.
+if ($key == 'entity_type' || $key == 'bundle') {
+if (empty($fci_join)) {
+$fci_join = $query->join('field_config_instance', 'fci', 'fc.id = fci.field_id');
+}
+$key = 'fci.' . $key;
+}
+else {
+$key = 'fc.' . $key;
+}
+$query->condition($key, $value);
+}
+if (!isset($include_additional['include_inactive']) || !$include_additional['include_inactive']) {
+$query
+->condition('fc.active', 1)
+->condition('fc.storage_active', 1);
+}
+$include_deleted = (isset($include_additional['include_deleted']) && $include_additional['include_deleted']);
+if (!$include_deleted) {
+$query->condition('fc.deleted', 0);
+}
+$fields = array();
+$results = $query->execute();
+foreach ($results as $record) {
+$field = unserialize($record['data']);
+$field['id'] = $record['id'];
+$field['field_name'] = $record['field_name'];
+$field['type'] = $record['type'];
+$field['module'] = $record['module'];
+$field['active'] = $record['active'];
+$field['storage']['type'] = $record['storage_type'];
+$field['storage']['module'] = $record['storage_module'];
+$field['storage']['active'] = $record['storage_active'];
+$field['locked'] = $record['locked'];
+$field['cardinality'] = $record['cardinality'];
+$field['translatable'] = $record['translatable'];
+$field['deleted'] = $record['deleted'];
+module_invoke_all('field_read_field', $field);
+// Populate storage information.
+module_load_install($field['module']);
+$schema = (array) module_invoke($field['module'], 'field_schema', $field);
+$schema += array('columns' => array(), 'indexes' => array());
+$field['columns'] = $schema['columns'];
+$field_name = $field['field_name'];
+if ($include_deleted) {
+$field_name = $field['id'];
+}
+$fields[$field_name] = $field;
+}
+return $fields;
+}
+/**
+* Marks a field and its instances and data for deletion.
+*
+* @param $field_name
+*   The field name to delete.
+*/
+function field_delete_field($field_name) {
+// Delete all non-deleted instances.
+$field = field_info_field($field_name);
+if (isset($field['bundles'])) {
+foreach ($field['bundles'] as $entity_type => $bundles) {
+foreach ($bundles as $bundle) {
+$instance = field_info_instance($entity_type, $field_name, $bundle);
+field_delete_instance($instance, FALSE);
+}
+}
+}
+// Mark field data for deletion.
+module_invoke($field['storage']['module'], 'field_storage_delete_field', $field);
+// Mark the field for deletion.
+db_update('field_config')
+->fields(array('deleted' => 1))
+->condition('field_name', $field_name)
+->execute();
+// Clear the cache.
+field_cache_clear();
+module_invoke_all('field_delete_field', $field);
+}
+/**
+* Creates an instance of a field, binding it to a bundle.
+*
+* @param $instance
+*   A field instance definition array. The field_name, entity_type and
+*   bundle properties are required. Other properties, if omitted,
+*   will be given the following default values:
+*   - label: the field name
+*   - description: empty string
+*   - required: FALSE
+*   - default_value_function: empty string
+*   - settings: each omitted setting is given the default value specified in
+*     hook_field_info().
+*   - widget:
+*     - type: the default widget specified in hook_field_info().
+*     - settings: each omitted setting is given the default value specified in
+*       hook_field_widget_info().
+*   - display:
+*     Settings for the 'default' view mode will be added if not present, and
+*     each view mode in the definition will be completed with the following
+*     default values:
+*     - label: 'above'
+*     - type: the default formatter specified in hook_field_info().
+*     - settings: each omitted setting is given the default value specified in
+*       hook_field_formatter_info().
+*     View modes not present in the definition are left empty, and the field
+*     will not be displayed in this mode.
+*
+* @return
+*   The $instance array with the id property filled in.
+*
+* @throws FieldException
+*
+* See: @link field Field API data structures @endlink.
+*/
+function field_create_instance($instance) {
+$field = field_read_field($instance['field_name']);
+if (empty($field)) {
+throw new FieldException(t("Attempt to create an instance of a field @field_name that doesn't exist or is currently inactive.", array('@field_name' => $instance['field_name'])));
+}
+// Check that the required properties exists.
+if (empty($instance['entity_type'])) {
+throw new FieldException(t('Attempt to create an instance of field @field_name without an entity type.', array('@field_name' => $instance['field_name'])));
+}
+if (empty($instance['bundle'])) {
+throw new FieldException(t('Attempt to create an instance of field @field_name without a bundle.', array('@field_name' => $instance['field_name'])));
+}
+// Check that the field can be attached to this entity type.
+if (!empty($field['entity_types']) && !in_array($instance['entity_type'], $field['entity_types'])) {
+throw new FieldException(t('Attempt to create an instance of field @field_name on forbidden entity type @entity_type.', array('@field_name' => $instance['field_name'], '@entity_type' => $instance['entity_type'])));
+}
+// Set the field id.
+$instance['field_id'] = $field['id'];
+// Note that we do *not* prevent creating a field on non-existing bundles,
+// because that would break the 'Body as field' upgrade for contrib
+// node types.
+// TODO: Check that the widget type is known and can handle the field type ?
+// TODO: Check that the formatters are known and can handle the field type ?
+// TODO: Check that the display view modes are known for the entity type ?
+// Those checks should probably happen in _field_write_instance() ?
+// Problem : this would mean that a UI module cannot update an instance with a disabled formatter.
+// Ensure the field instance is unique within the bundle.
+// We only check for instances of active fields, since adding an instance of
+// a disabled field is not supported.
+$prior_instance = field_read_instance($instance['entity_type'], $instance['field_name'], $instance['bundle']);
+if (!empty($prior_instance)) {
+$message = t('Attempt to create an instance of field @field_name on bundle @bundle that already has an instance of that field.', array('@field_name' => $instance['field_name'], '@bundle' => $instance['bundle']));
+throw new FieldException($message);
+}
+_field_write_instance($instance);
+// Clear caches
+field_cache_clear();
+// Invoke external hooks after the cache is cleared for API consistency.
+module_invoke_all('field_create_instance', $instance);
+return $instance;
+}
+/**
+* Updates an instance of a field.
+*
+* @param $instance
+*   An associative array representing an instance structure. The following
+*   required array elements specify which field instance is being updated:
+*   - entity_type: The type of the entity the field is attached to.
+*   - bundle: The bundle this field belongs to.
+*   - field_name: The name of an existing field.
+*   The other array elements represent properties of the instance, and all
+*   properties must be specified or their default values will be used (except
+*   internal-use properties, which are assigned automatically). To avoid
+*   losing the previously stored properties of the instance when making a
+*   change, first load the instance with field_info_instance(), then override
+*   the values you want to override, and finally save using this function.
+*   Example:
+*   @code
+*   // Fetch an instance info array.
+*   $instance_info = field_info_instance($entity_type, $field_name, $bundle_name);
+*   // Change a single property in the instance definition.
+*   $instance_info['required'] = TRUE;
+*   // Write the changed definition back.
+*   field_update_instance($instance_info);
+*   @endcode
+*
+* @throws FieldException
+*
+* @see field_info_instance()
+* @see field_create_instance()
+*/
+function field_update_instance($instance) {
+// Check that the specified field exists.
+$field = field_read_field($instance['field_name']);
+if (empty($field)) {
+throw new FieldException(t('Attempt to update an instance of a nonexistent field @field.', array('@field' => $instance['field_name'])));
+}
+// Check that the field instance exists (even if it is inactive, since we
+// want to be able to replace inactive widgets with new ones).
+$prior_instance = field_read_instance($instance['entity_type'], $instance['field_name'], $instance['bundle'], array('include_inactive' => TRUE));
+if (empty($prior_instance)) {
+throw new FieldException(t("Attempt to update an instance of field @field on bundle @bundle that doesn't exist.", array('@field' => $instance['field_name'], '@bundle' => $instance['bundle'])));
+}
+$instance['id'] = $prior_instance['id'];
+$instance['field_id'] = $prior_instance['field_id'];
+_field_write_instance($instance, TRUE);
+// Clear caches.
+field_cache_clear();
+module_invoke_all('field_update_instance', $instance, $prior_instance);
+}
+/**
+* Stores an instance record in the field configuration database.
+*
+* @param $instance
+*   An instance structure.
+* @param $update
+*   Whether this is a new or existing instance.
+*/
+function _field_write_instance($instance, $update = FALSE) {
+$field = field_read_field($instance['field_name']);
+$field_type = field_info_field_types($field['type']);
+// Set defaults.
+$instance += array(
+'settings' => array(),
+'display' => array(),
+'widget' => array(),
+'required' => FALSE,
+'label' => $instance['field_name'],
+'description' => '',
+'deleted' => 0,
+);
+// Set default instance settings.
+$instance['settings'] += field_info_instance_settings($field['type']);
+// Set default widget and settings.
+$instance['widget'] += array(
+// TODO: what if no 'default_widget' specified ?
+'type' => $field_type['default_widget'],
+'settings' => array(),
+);
+// If no weight specified, make sure the field sinks at the bottom.
+if (!isset($instance['widget']['weight'])) {
+$max_weight = field_info_max_weight($instance['entity_type'], $instance['bundle'], 'form');
+$instance['widget']['weight'] = isset($max_weight) ? $max_weight + 1 : 0;
+}
+// Check widget module.
+$widget_type = field_info_widget_types($instance['widget']['type']);
+$instance['widget']['module'] = $widget_type['module'];
+$instance['widget']['settings'] += field_info_widget_settings($instance['widget']['type']);
+// Make sure there are at least display settings for the 'default' view mode,
+// and fill in defaults for each view mode specified in the definition.
+$instance['display'] += array(
+'default' => array(),
+);
+foreach ($instance['display'] as $view_mode => $display) {
+$display += array(
+'label' => 'above',
+'type' => isset($field_type['default_formatter']) ? $field_type['default_formatter'] : 'hidden',
+'settings' => array(),
+);
+if ($display['type'] != 'hidden') {
+$formatter_type = field_info_formatter_types($display['type']);
+$display['module'] = $formatter_type['module'];
+$display['settings'] += field_info_formatter_settings($display['type']);
+}
+// If no weight specified, make sure the field sinks at the bottom.
+if (!isset($display['weight'])) {
+$max_weight = field_info_max_weight($instance['entity_type'], $instance['bundle'], $view_mode);
+$display['weight'] = isset($max_weight) ? $max_weight + 1 : 0;
+}
+$instance['display'][$view_mode] = $display;
+}
+// The serialized 'data' column contains everything from $instance that does
+// not have its own column and is not automatically populated when the
+// instance is read.
+$data = $instance;
+unset($data['id'], $data['field_id'], $data['field_name'], $data['entity_type'], $data['bundle'], $data['deleted']);
+$record = array(
+'field_id' => $instance['field_id'],
+'field_name' => $instance['field_name'],
+'entity_type' => $instance['entity_type'],
+'bundle' => $instance['bundle'],
+'data' => $data,
+'deleted' => $instance['deleted'],
+);
+// We need to tell drupal_update_record() the primary keys to trigger an
+// update.
+if ($update) {
+$record['id'] = $instance['id'];
+$primary_key = array('id');
+}
+else {
+$primary_key = array();
+}
+drupal_write_record('field_config_instance', $record, $primary_key);
+}
+/**
+* Reads a single instance record from the database.
+*
+* Generally, you should use field_info_instance() instead, as it
+* provides caching and allows other modules the opportunity to
+* append additional formatters, widgets, and other information.
+*
+* @param $entity_type
+*   The type of entity to which the field is bound.
+* @param $field_name
+*   The field name to read.
+* @param $bundle
+*   The bundle to which the field is bound.
+* @param array $include_additional
+*   The default behavior of this function is to not return an instance that
+*   has been deleted, or whose field is inactive. Setting
+*   $include_additional['include_inactive'] or
+*   $include_additional['include_deleted'] to TRUE will override this
+*   behavior.
+* @return
+*   An instance structure, or FALSE.
+*/
+function field_read_instance($entity_type, $field_name, $bundle, $include_additional = array()) {
+$instances = field_read_instances(array('entity_type' => $entity_type, 'field_name' => $field_name, 'bundle' => $bundle), $include_additional);
+return $instances ? current($instances) : FALSE;
+}
+/**
+* Reads in field instances that match an array of conditions.
+*
+* @param $param
+*   An array of properties to use in selecting a field
+*   instance. Valid keys include any column of the
+*   field_config_instance table. If NULL, all instances will be returned.
+* @param $include_additional
+*   The default behavior of this function is to not return field
+*   instances that have been marked deleted, or whose field is inactive.
+*   Setting $include_additional['include_inactive'] or
+*   $include_additional['include_deleted'] to TRUE will override this
+*   behavior.
+* @return
+*   An array of instances matching the arguments.
+*/
+function field_read_instances($params = array(), $include_additional = array()) {
+$include_inactive = isset($include_additional['include_inactive']) && $include_additional['include_inactive'];
+$include_deleted = isset($include_additional['include_deleted']) && $include_additional['include_deleted'];
+$query = db_select('field_config_instance', 'fci', array('fetch' => PDO::FETCH_ASSOC));
+$query->join('field_config', 'fc', 'fc.id = fci.field_id');
+$query->fields('fci');
+// Turn the conditions into a query.
+foreach ($params as $key => $value) {
+$query->condition('fci.' . $key, $value);
+}
+if (!$include_inactive) {
+$query
+->condition('fc.active', 1)
+->condition('fc.storage_active', 1);
+}
+if (!$include_deleted) {
+$query->condition('fc.deleted', 0);
+$query->condition('fci.deleted', 0);
+}
+$instances = array();
+$results = $query->execute();
+foreach ($results as $record) {
+// Filter out instances on unknown entity types (for instance because the
+// module exposing them was disabled).
+$entity_info = entity_get_info($record['entity_type']);
+if ($include_inactive || $entity_info) {
+$instance = unserialize($record['data']);
+$instance['id'] = $record['id'];
+$instance['field_id'] = $record['field_id'];
+$instance['field_name'] = $record['field_name'];
+$instance['entity_type'] = $record['entity_type'];
+$instance['bundle'] = $record['bundle'];
+$instance['deleted'] = $record['deleted'];
+module_invoke_all('field_read_instance', $instance);
+$instances[] = $instance;
+}
+}
+return $instances;
+}
+/**
+* Marks a field instance and its data for deletion.
+*
+* @param $instance
+*   An instance structure.
+* @param $field_cleanup
+*   If TRUE, the field will be deleted as well if its last instance is being
+*   deleted. If FALSE, it is the caller's responsibility to handle the case of
+*   fields left without instances. Defaults to TRUE.
+*/
+function field_delete_instance($instance, $field_cleanup = TRUE) {
+// Mark the field instance for deletion.
+db_update('field_config_instance')
+->fields(array('deleted' => 1))
+->condition('field_name', $instance['field_name'])
+->condition('entity_type', $instance['entity_type'])
+->condition('bundle', $instance['bundle'])
+->execute();
+// Clear the cache.
+field_cache_clear();
+// Mark instance data for deletion.
+$field = field_info_field($instance['field_name']);
+module_invoke($field['storage']['module'], 'field_storage_delete_instance', $instance);
+// Let modules react to the deletion of the instance.
+module_invoke_all('field_delete_instance', $instance);
+// Delete the field itself if we just deleted its last instance.
+if ($field_cleanup && count($field['bundles']) == 0) {
+field_delete_field($field['field_name']);
+}
+}
+/**
+* @} End of "defgroup field_crud".
+*/
+/**
+* @defgroup field_purge Field API bulk data deletion
+* @{
+* Clean up after Field API bulk deletion operations.
+*
+* Field API provides functions for deleting data attached to individual
+* entities as well as deleting entire fields or field instances in a single
+* operation.
+*
+* Deleting field data items for an entity with field_attach_delete() involves
+* three separate operations:
+* - Invoking the Field Type API hook_field_delete() for each field on the
+* entity. The hook for each field type receives the entity and the specific
+* field being deleted. A file field module might use this hook to delete
+* uploaded files from the filesystem.
+* - Invoking the Field Storage API hook_field_storage_delete() to remove
+* data from the primary field storage. The hook implementation receives the
+* entity being deleted and deletes data for all of the entity's bundle's
+* fields.
+* - Invoking the global Field Attach API hook_field_attach_delete() for all
+* modules that implement it. Each hook implementation receives the entity
+* being deleted and can operate on whichever subset of the entity's bundle's
+* fields it chooses to.
+*
+* These hooks are invoked immediately when field_attach_delete() is
+* called. Similar operations are performed for field_attach_delete_revision().
+*
+* When a field, bundle, or field instance is deleted, it is not practical to
+* invoke these hooks immediately on every affected entity in a single page
+* request; there could be thousands or millions of them. Instead, the
+* appropriate field data items, instances, and/or fields are marked as deleted
+* so that subsequent load or query operations will not return them. Later, a
+* separate process cleans up, or "purges", the marked-as-deleted data by going
+* through the three-step process described above and, finally, removing
+* deleted field and instance records.
+*
+* Purging field data is made somewhat tricky by the fact that, while
+* field_attach_delete() has a complete entity to pass to the various deletion
+* hooks, the Field API purge process only has the field data it has previously
+* stored. It cannot reconstruct complete original entities to pass to the
+* deletion hooks. It is even possible that the original entity to which some
+* Field API data was attached has been itself deleted before the field purge
+* operation takes place.
+*
+* Field API resolves this problem by using "pseudo-entities" during purge
+* operations. A pseudo-entity contains only the information from the original
+* entity that Field API knows about: entity type, id, revision id, and
+* bundle. It also contains the field data for whichever field instance is
+* currently being purged. For example, suppose that the node type 'story' used
+* to contain a field called 'subtitle' but the field was deleted. If node 37
+* was a story with a subtitle, the pseudo-entity passed to the purge hooks
+* would look something like this:
+*
+* @code
+*   $entity = stdClass Object(
+*     [nid] => 37,
+*     [vid] => 37,
+*     [type] => 'story',
+*     [subtitle] => array(
+*       [0] => array(
+*         'value' => 'subtitle text',
+*       ),
+*     ),
+*   );
+* @endcode
+*
+* See @link field Field API @endlink for information about the other parts of
+* the Field API.
+*/
+/**
+* Purges a batch of deleted Field API data, instances, or fields.
+*
+* This function will purge deleted field data in batches. The batch size
+* is defined as an argument to the function, and once each batch is finished,
+* it continues with the next batch until all have completed. If a deleted field
+* instance with no remaining data records is found, the instance itself will
+* be purged. If a deleted field with no remaining field instances is found, the
+* field itself will be purged.
+*
+* @param $batch_size
+*   The maximum number of field data records to purge before returning.
+*/
+function field_purge_batch($batch_size) {
+// Retrieve all deleted field instances. We cannot use field_info_instances()
+// because that function does not return deleted instances.
+$instances = field_read_instances(array('deleted' => 1), array('include_deleted' => 1));
+foreach ($instances as $instance) {
+// field_purge_data() will need the field array.
+$field = field_info_field_by_id($instance['field_id']);
+// Retrieve some entities.
+$query = new EntityFieldQuery();
+$results = $query
+->fieldCondition($field)
+->entityCondition('bundle', $instance['bundle'])
+->deleted(TRUE)
+->range(0, $batch_size)
+->execute();
+if ($results) {
+foreach ($results as $entity_type => $stub_entities) {
+field_attach_load($entity_type, $stub_entities, FIELD_LOAD_CURRENT, array('field_id' => $field['id'], 'deleted' => 1));
+foreach ($stub_entities as $stub_entity) {
+// Purge the data for the entity.
+field_purge_data($entity_type, $stub_entity, $field, $instance);
+}
+}
+}
+else {
+// No field data remains for the instance, so we can remove it.
+field_purge_instance($instance);
+}
+}
+// Retrieve all deleted fields. Any that have no instances can be purged.
+$fields = field_read_fields(array('deleted' => 1), array('include_deleted' => 1));
+foreach ($fields as $field) {
+$instances = field_read_instances(array('field_id' => $field['id']), array('include_deleted' => 1));
+if (empty($instances)) {
+field_purge_field($field);
+}
+}
+}
+/**
+* Purges the field data for a single field on a single pseudo-entity.
+*
+* This is basically the same as field_attach_delete() except it only applies
+* to a single field. The entity itself is not being deleted, and it is quite
+* possible that other field data will remain attached to it.
+*
+* @param $entity_type
+*   The type of $entity; e.g. 'node' or 'user'.
+* @param $entity
+*   The pseudo-entity whose field data is being purged.
+* @param $field
+*   The (possibly deleted) field whose data is being purged.
+* @param $instance
+*   The deleted field instance whose data is being purged.
+*/
+function field_purge_data($entity_type, $entity, $field, $instance) {
+// Each field type's hook_field_delete() only expects to operate on a single
+// field at a time, so we can use it as-is for purging.
+$options = array('field_id' => $instance['field_id'], 'deleted' => TRUE);
+_field_invoke('delete', $entity_type, $entity, $dummy, $dummy, $options);
+// Tell the field storage system to purge the data.
+module_invoke($field['storage']['module'], 'field_storage_purge', $entity_type, $entity, $field, $instance);
+// Let other modules act on purging the data.
+foreach (module_implements('field_attach_purge') as $module) {
+$function = $module . '_field_attach_purge';
+$function($entity_type, $entity, $field, $instance);
+}
+}
+/**
+* Purges a field instance record from the database.
+*
+* This function assumes all data for the instance has already been purged, and
+* should only be called by field_purge_batch().
+*
+* @param $instance
+*   The instance record to purge.
+*/
+function field_purge_instance($instance) {
+db_delete('field_config_instance')
+->condition('id', $instance['id'])
+->execute();
+// Notify the storage engine.
+$field = field_info_field_by_id($instance['field_id']);
+module_invoke($field['storage']['module'], 'field_storage_purge_instance', $instance);
+// Clear the cache.
+field_info_cache_clear();
+// Invoke external hooks after the cache is cleared for API consistency.
+module_invoke_all('field_purge_instance', $instance);
+}
+/**
+* Purges a field record from the database.
+*
+* This function assumes all instances for the field has already been purged,
+* and should only be called by field_purge_batch().
+*
+* @param $field
+*   The field record to purge.
+*/
+function field_purge_field($field) {
+$instances = field_read_instances(array('field_id' => $field['id']), array('include_deleted' => 1));
+if (count($instances) > 0) {
+throw new FieldException(t('Attempt to purge a field @field_name that still has instances.', array('@field_name' => $field['field_name'])));
+}
+db_delete('field_config')
+->condition('id', $field['id'])
+->execute();
+// Notify the storage engine.
+module_invoke($field['storage']['module'], 'field_storage_purge_field', $field);
+// Clear the cache.
+field_info_cache_clear();
+// Invoke external hooks after the cache is cleared for API consistency.
+module_invoke_all('field_purge_field', $field);
+}
+/**
+* @} End of "defgroup field_purge".
+*/