drupal/core/modules/field/field.module

<?php
/**
 * @file
 * Attach custom data fields to Drupal entities.
 */

use Drupal\Component\Utility\Html;
use Drupal\Component\Utility\SafeMarkup;
use Drupal\Component\Utility\Xss;
use Drupal\Core\Config\ConfigImporter;
use Drupal\Core\Entity\EntityTypeInterface;
use Drupal\Core\Extension\Extension;
use Drupal\Core\Form\FormStateInterface;
use Drupal\Core\Routing\RouteMatchInterface;

/*
 * Load all public Field API functions. Drupal currently has no
 * mechanism for auto-loading core APIs, so we have to load them on
 * every page request.
 */
require_once __DIR__ . '/field.purge.inc';

/**
 * @defgroup field Field API
 * @{
 * Attaches custom data fields to Drupal entities.
 *
 * The Field API allows custom data fields to be attached to Drupal entities and
 * takes care of storing, loading, editing, and rendering field data. Any entity
 * type (node, user, etc.) can use the Field API to make itself "fieldable" and
 * thus allow fields to be attached to it. Other modules can provide a user
 * interface for managing custom fields via a web browser as well as a wide and
 * flexible variety of data type, form element, and display format capabilities.
 *
 * The Field API defines two primary data structures, Field and Instance, and
 * the concept of a Bundle. A Field defines a particular type of data that can
 * be attached to entities. A Field Instance is a Field attached to a single
 * Bundle. A Bundle is a set of fields that are treated as a group by the Field
 * Attach API and is related to a single fieldable entity type.
 *
 * For example, suppose a site administrator wants Article nodes to have a
 * subtitle and photo. Using the Field API or Field UI module, the administrator
 * creates a field named 'subtitle' of type 'text' and a field named 'photo' of
 * type 'image'. The administrator (again, via a UI) creates two Field
 * Instances, one attaching the field 'subtitle' to the 'node' bundle 'article'
 * and one attaching the field 'photo' to the 'node' bundle 'article'. When the
 * node storage loads an Article node, it loads the values of the
 * 'subtitle' and 'photo' fields because they are both attached to the 'node'
 * bundle 'article'.
 *
 * - @link field_types Field Types API @endlink: Defines field types, widget
 *   types, and display formatters. Field modules use this API to provide field
 *   types like Text and Node Reference along with the associated form elements
 *   and display formatters.
 *
 * - @link field_purge Field API bulk data deletion @endlink: Cleans up after
 *   bulk deletion operations such as deletion of field or field_instance.
 */

/**
 * Implements hook_help().
 */
function field_help($route_name, RouteMatchInterface $route_match) {
  switch ($route_name) {
    case 'help.page.field':
      $output = '';
      $output .= '<h3>' . t('About') . '</h3>';
      $output .= '<p>' . t('The Field module allows custom data fields to be defined for <a href="!entity-help"><em>entity</em></a> types (entities include content items, comments, user accounts, and taxonomy terms). The Field module takes care of storing, loading, editing, and rendering field data. Most users will not interact with the Field module directly, but will instead use the <a href="!field-ui-help">Field UI module</a> user interface. Module developers can use the Field API to make new entity types "fieldable" and thus allow fields to be attached to them. For more information, see the <a href="!field">online documentation for the Field module</a>.', array('!entity-help' => \Drupal::url('help.page', array('name' => 'entity')), '!field-ui-help' => \Drupal::url('help.page', array('name' => 'field_ui')), '!field' => 'https://drupal.org/documentation/modules/field')) . '</p>';
      $output .= '<h3>' . t('Uses') . '</h3>';
      $output .= '<dl>';
      $output .= '<dt>' . t('Enabling field types') . '</dt>';
      $output .= '<dd>' . t('The Field module provides the infrastructure for fields and field attachment; the field types and input widgets themselves are provided by additional modules. Some of the modules are required; the optional modules can be enabled from the <a href="!modules">Extend administration page</a>. Additional fields and widgets may be provided by contributed modules, which you can find in the <a href="!contrib">contributed module section of Drupal.org</a>.', array('!modules' => \Drupal::url('system.modules_list'), '!contrib' => 'https://drupal.org/project/modules'));

      // Make a list of all widget and field modules currently enabled, ordered
      // by displayed module name (module names are not translated).
      $items = array();
      $info = system_get_info('module');
      $field_widgets = \Drupal::service('plugin.manager.field.widget')->getDefinitions();
      $field_types = \Drupal::service('plugin.manager.field.field_type')->getUiDefinitions();
      $providers = array();
      foreach (array_merge($field_types, $field_widgets) as $plugin) {
        $providers[] = $plugin['provider'];
      }
      $providers = array_unique($providers);
      sort($providers);
      foreach ($providers as $provider) {
        // Skip plugins provided by core components as they do not implement
        // hook_help().
        if (isset($info[$provider]['name'])) {
          $display = $info[$provider]['name'];
          if (\Drupal::moduleHandler()->implementsHook($provider, 'help')) {
            $items[] = l($display, 'admin/help/' . $provider);
          }
          else {
            $items[] = $display;
          }
        }
      }
      if ($items) {
        $output .= ' ' . t('Currently enabled field and input widget modules:');
        $item_list = array(
          '#theme' => 'item_list',
          '#items' => $items,
        );
        $output .= drupal_render($item_list);
      }
      return $output;
  }
}

/**
 * Implements hook_cron().
 */
function field_cron() {
  // Do a pass of purging on deleted Field API data, if any exists.
  $limit = \Drupal::config('field.settings')->get('purge_batch_size');
  field_purge_batch($limit);
}

/**
 * Implements hook_system_info_alter().
 *
 * Goes through a list of all modules that provide a field type and makes them
 * required if there are any active fields of that type.
 */
function field_system_info_alter(&$info, Extension $file, $type) {
  // It is not safe to call entity_load_multiple_by_properties() during
  // maintenance mode.
  if ($type == 'module' && !defined('MAINTENANCE_MODE')) {
    $fields = entity_load_multiple_by_properties('field_storage_config', array('module' => $file->getName(), 'include_deleted' => TRUE));
    if ($fields) {
      $info['required'] = TRUE;

      // Provide an explanation message (only mention pending deletions if there
      // remains no actual, non-deleted fields)
      $non_deleted = FALSE;
      foreach ($fields as $field) {
        if (empty($field->deleted)) {
          $non_deleted = TRUE;
          break;
        }
      }
      if ($non_deleted) {
        if (\Drupal::moduleHandler()->moduleExists('field_ui')) {
          $explanation = t('Field type(s) in use - see <a href="@fields-page">Field list</a>', array('@fields-page' => url('admin/reports/fields')));
        }
        else {
          $explanation = t('Fields type(s) in use');
        }
      }
      else {
        $explanation = t('Fields pending deletion');
      }
      $info['explanation'] = $explanation;
    }
  }
}

/**
 * Implements hook_entity_field_storage_info().
 */
function field_entity_field_storage_info(\Drupal\Core\Entity\EntityTypeInterface $entity_type) {
  // Expose storage definitions for all exposed bundle fields.
  if ($entity_type->isFieldable()) {
    // Query by filtering on the ID as this is more efficient than filtering
    // on the entity_type property directly.
    $ids = \Drupal::entityQuery('field_storage_config')
      ->condition('id', $entity_type->id() . '.', 'STARTS_WITH')
      ->execute();

    // Fetch all fields and key them by field name.
    $field_storages = entity_load_multiple('field_storage_config', $ids);
    $result = array();
    foreach ($field_storages as $field_storage) {
      $result[$field_storage->getName()] = $field_storage;
    }
    return $result;
  }
}

/**
 * Implements hook_entity_bundle_field_info().
 */
function field_entity_bundle_field_info(EntityTypeInterface $entity_type, $bundle, array $base_field_definitions) {
  if ($entity_type->isFieldable()) {
    // Query by filtering on the ID as this is more efficient than filtering
    // on the entity_type property directly.
    $ids = \Drupal::entityQuery('field_instance_config')
      ->condition('id', $entity_type->id() . '.' . $bundle . '.', 'STARTS_WITH')
      ->execute();

    // Fetch all fields and key them by field name.
    $field_instance_configs = entity_load_multiple('field_instance_config', $ids);
    $result = array();
    foreach ($field_instance_configs as $field_instance) {
      $result[$field_instance->getName()] = $field_instance;
    }
    return $result;
  }
}

/**
 * Implements hook_entity_bundle_rename().
 */
function field_entity_bundle_rename($entity_type, $bundle_old, $bundle_new) {
  $instances = entity_load_multiple_by_properties('field_instance_config', array('entity_type' => $entity_type, 'bundle' => $bundle_old, 'include_deleted' => TRUE));
  foreach ($instances as $instance) {
    $id_new = $instance->entity_type . '.' . $bundle_new . '.' . $instance->field_name;
    $instance->set('id', $id_new);
    $instance->bundle = $bundle_new;
    // Save non-deleted instances.
    if (!$instance->isDeleted()) {
      $instance->allowBundleRename();
      $instance->save();
    }
    // Update deleted instances directly in the state storage.
    else {
      $state = \Drupal::state();
      $deleted_instances = $state->get('field.instance.deleted') ?: array();
      $deleted_instances[$instance->uuid] = $instance->toArray();
      $state->set('field.instance.deleted', $deleted_instances);
    }
  }
}

/**
 * Implements hook_entity_bundle_delete().
 *
 * 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 as
 * 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).
 */
function field_entity_bundle_delete($entity_type, $bundle) {
  // Get the instances on the bundle. entity_load_multiple_by_properties() must
  // be used here since field_info_instances() does not return instances for
  // disabled entity types or bundles.
  $instances = entity_load_multiple_by_properties('field_instance_config', array('entity_type' => $entity_type, 'bundle' => $bundle));
  foreach ($instances as $instance) {
    $instance->delete();
  }
}

/**
 * Filters an HTML string to prevent cross-site-scripting (XSS) vulnerabilities.
 *
 * Like \Drupal\Component\Utility\Xss::filterAdmin(), but with a shorter list
 * of allowed tags.
 *
 * Used for items entered by administrators, like field descriptions, allowed
 * values, where some (mainly inline) mark-up may be desired (so
 * drupal_htmlspecialchars() is not acceptable).
 *
 * @param $string
 *   The string with raw HTML in it.
 *
 * @return
 *   An XSS safe version of $string, or an empty string if $string is not valid
 *   UTF-8.
 */
function field_filter_xss($string) {
  return SafeMarkup::set(Html::normalize(Xss::filter($string, _field_filter_xss_allowed_tags())));
}

/**
 * Returns a list of tags allowed by field_filter_xss().
 */
function _field_filter_xss_allowed_tags() {
  return array('a', 'b', 'big',  'code', 'del', 'em', 'i', 'ins',  'pre', 'q', 'small', 'span', 'strong', 'sub', 'sup', 'tt', 'ol', 'ul', 'li', 'p', 'br', 'img');
}

/**
 * Returns a human-readable list of allowed tags for display in help texts.
 */
function _field_filter_xss_display_allowed_tags() {
  return '<' . implode('> <', _field_filter_xss_allowed_tags()) . '>';
}

/**
 * @} End of "defgroup field".
 */

/**
 * Assembles a partial entity structure with initial IDs.
 *
 * @param object $ids
 *   An object with the properties entity_type (required), entity_id (required),
 *   revision_id (optional) and bundle (optional).
 *
 * @return \Drupal\Core\Entity\EntityInterface
 *   An entity, initialized with the provided IDs.
 */
function _field_create_entity_from_ids($ids) {
  $id_properties = array();
  $entity_type = \Drupal::entityManager()->getDefinition($ids->entity_type);
  if ($id_key = $entity_type->getKey('id')) {
    $id_properties[$id_key] = $ids->entity_id;
  }
  if (isset($ids->revision_id) && $revision_key = $entity_type->getKey('revision')) {
    $id_properties[$revision_key] = $ids->revision_id;
  }
  if (isset($ids->bundle) && $bundle_key = $entity_type->getKey('bundle')) {
    $id_properties[$bundle_key] = $ids->bundle;
  }
  return entity_create($ids->entity_type, $id_properties);
}

/**
 * Implements hook_hook_info().
 */
function field_hook_info() {
  $hooks['field_views_data'] = array(
    'group' => 'views',
  );
  $hooks['field_views_data_alter'] = array(
    'group' => 'views',
  );

  return $hooks;
}

/**
 * Implements hook_config_import_steps_alter().
 */
function field_config_import_steps_alter(&$sync_steps, ConfigImporter $config_importer) {
  $field_storages = \Drupal\field\ConfigImporterFieldPurger::getFieldStoragesToPurge(
    $config_importer->getStorageComparer()->getSourceStorage()->read('core.extension'),
    $config_importer->getStorageComparer()->getChangelist('delete')
  );
  if ($field_storages) {
    // Add a step to the beginning of the configuration synchronization process
    // to purge field data where the module that provides the field is being
    // uninstalled.
    array_unshift($sync_steps, array('\Drupal\field\ConfigImporterFieldPurger', 'process'));
  };
}

/**
 * Implements hook_form_FORM_ID_alter().
 *
 * Adds a warning if field data will be permanently removed by the configuration
 * synchronization.
 *
 * @see \Drupal\field\ConfigImporterFieldPurger
 */
function field_form_config_admin_import_form_alter(&$form, FormStateInterface $form_state) {
  // Only display the message when there is a storage comparer available and the
  // form is not submitted.
  if (isset($form_state['storage_comparer']) && empty($form_state['input'])) {
    $field_storages = \Drupal\field\ConfigImporterFieldPurger::getFieldStoragesToPurge(
      $form_state['storage_comparer']->getSourceStorage()->read('core.extension'),
      $form_state['storage_comparer']->getChangelist('delete')
    );
    if ($field_storages) {
      foreach ($field_storages as $field) {
        $field_labels[] = $field->label();
      }
      drupal_set_message(\Drupal::translation()->formatPlural(
        count($field_storages),
        'This synchronization will delete data from the field %fields.',
        'This synchronization will delete data from the fields: %fields.',
        array('%fields' => implode(', ', $field_labels))
      ), 'warning');
    }
  }
}