drupal/modules/field/field.module

<?php
// $Id$
/**
 * @file
 * Attach custom data fields to Drupal objects.
 */

/*
 * 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.
 */
module_load_include('inc', 'field', 'field.crud');
module_load_include('inc', 'field', 'field.default');
module_load_include('inc', 'field', 'field.info');
module_load_include('inc', 'field', 'field.multilingual');
module_load_include('inc', 'field', 'field.attach');
module_load_include('inc', 'field', 'field.form');

/**
 * @defgroup field Field API
 * @{
 * Attach custom data fields to Drupal objects.
 *
 * The Field API allows custom data fields to be attached to Drupal
 * objects and takes care of storing, loading, editing, and rendering
 * field data. Any object 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.
 *
 * - @link field_structs Data structures: Field, Instance, Bundle @endlink.
 *
 * - @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_crud Field CRUD API @endlink. Create, updates, and
 *   deletes fields, bundles (a.k.a. "content types"), and instances.
 *   Modules use this API, often in hook_install(), to create
 *   custom data structures.
 *
 * - @link field_attach Field Attach API @endlink. Connects object
 *   types to the Field API. Field Attach API functions load, store,
 *   generate Form API structures, display, and perform a vareity of
 *   other functions for field data connected to individual objects.
 *   Fieldable object types like node and user use this API to make
 *   themselves fieldable.
 *
 * - @link field_info Field Info API @endlink. Exposes information
 *   about all fields, instances, widgets, and related information
 *   defined by or with the Field API.
 *
 * - @link field_storage Field Storage API @endlink. Provides a
 *   pluggable back-end storage system for actual field data. The
 *   default implementation, field_sql_storage.module, stores field data
 *   in the local SQL database.

 * - @link field_purge Field API bulk data deletion @endlink. Cleans
 *   up after bulk deletion operations such as field_delete_field()
 *   and field_delete_instance().
 */

/**
 * Value for $field['cardinality'] property to indicate it can hold an
 * unlimited number of values.
 */
define('FIELD_CARDINALITY_UNLIMITED', -1);

/**
 * The language code assigned to untranslatable fields.
 *
 * Defined by ISO639-2 for "No linguistic content / Not applicable".
 */
define('FIELD_LANGUAGE_NONE', 'zxx');

/**
 * TODO
 */
define('FIELD_BEHAVIOR_NONE', 0x0001);
/**
 * TODO
 */
define('FIELD_BEHAVIOR_DEFAULT', 0x0002);
/**
 * TODO
 */
define('FIELD_BEHAVIOR_CUSTOM', 0x0004);

/**
 * Age argument for loading the most recent version of an object's
 * field data with field_attach_load().
 */
define('FIELD_LOAD_CURRENT', 'FIELD_LOAD_CURRENT');
/**
 * Age argument for loading the version of an object's field data
 * specified in the object with field_attach_load().
 */
define('FIELD_LOAD_REVISION', 'FIELD_LOAD_REVISION');

/**
 * @name Field query flags
 * @{
 * Flags for field_attach_query().
 */

/**
 * Limit argument for field_attach_query() to request all available
 * objects instead of a limited number.
 */
define('FIELD_QUERY_NO_LIMIT', 'FIELD_QUERY_NO_LIMIT');

/**
 * Cursor return value for field_attach_query() to indicate that no
 * more data is available.
 */
define('FIELD_QUERY_COMPLETE', 'FIELD_QUERY_COMPLETE');

/**
 * @} End of "Field query flags".
 */

/**
 * Base class for all exceptions thrown by Field API functions.
 *
 * This class has no functionality of its own other than allowing all
 * Field API exceptions to be caught by a single catch block.
 */
class FieldException extends Exception {}

/**
 * Exception class thrown by hook_field_update_forbid().
 */
class FieldUpdateForbiddenException extends FieldException {}

/**
 * Implement hook_flush_caches.
 */
function field_flush_caches() {
  return array('cache_field');
}

/**
 * Implement hook_help().
 */
function field_help($path, $arg) {
  switch ($path) {
    case 'admin/help#field':
      $output = '<p>' . t('The Field API allows custom data fields to be attached to Drupal objects and takes care of storing, loading, editing, and rendering field data. Any object type (node, user, etc.) can use the Field API to make itself "fieldable" and thus allow fields to be attached to it.') . '</p>';
      return $output;
  }
}

/**
 * Implement hook_theme().
 */
function field_theme() {
  $path = drupal_get_path('module', 'field') . '/theme';
  $items = array(
    'field' => array(
      'template' => 'field',
      'arguments' => array('element' => NULL),
      'path' => $path,
    ),
    'field_multiple_value_form' => array(
      'arguments' => array('element' => NULL),
    ),
  );
  $field_formatters = field_info_formatter_types(NULL);
  foreach ($field_formatters as $key => $field_formatter) {
    $items['field_formatter_' . $key] = array(
      'arguments' => array('element' => NULL),
    );
    if (isset($field_formatter['theme'])) {
      $items['field_formatter_' . $key] += $field_formatter['theme'];
    }
  }
  return $items;
}

/**
 * Implement hook_cron().
 *
 * Purges some deleted Field API data, if any exists.
 */
function field_cron() {
  $limit = variable_get('field_purge_batch_size', 10);
  field_purge_batch($limit);
}

/**
 * Implement hook_modules_installed().
 */
function field_modules_installed($modules) {
  field_cache_clear();
}

/**
 * Implement hook_modules_uninstalled().
 */
function field_modules_uninstalled($modules) {
  module_load_include('inc', 'field', 'field.crud');
  foreach ($modules as $module) {
    // TODO D7: field_module_delete is not yet implemented
    // field_module_delete($module);
  }
}

/**
 * Implement hook_modules_enabled().
 */
function field_modules_enabled($modules) {
  foreach ($modules as $module) {
    field_associate_fields($module);
  }
  field_cache_clear();
}

/**
 * Implement hook_modules_disabled().
 */
function field_modules_disabled($modules) {
  foreach ($modules as $module) {
    db_update('field_config')
      ->fields(array('active' => 0))
      ->condition('module', $module)
      ->execute();
    db_update('field_config')
      ->fields(array('storage_active' => 0))
      ->condition('storage_module', $module)
      ->execute();
    field_cache_clear(TRUE);
  }
}

/**
 * Allows a module to update the database for fields and columns it controls.
 *
 * @param string $module
 *   The name of the module to update on.
 */
function field_associate_fields($module) {
  // Associate field types.
  $field_types =(array) module_invoke($module, 'field_info');
  foreach ($field_types as $name => $field_info) {
    watchdog('field', 'Updating field type %type with module %module.', array('%type' => $name, '%module' => $module));
    db_update('field_config')
      ->fields(array('module' => $module, 'active' => 1))
      ->condition('type', $name)
      ->execute();
  }
  // Associate storage backends.
  $storage_types = (array) module_invoke($module, 'field_storage_info');
  foreach ($storage_types as $name => $storage_info) {
    watchdog('field', 'Updating field storage %type with module %module.', array('%type' => $name, '%module' => $module));
    db_update('field_config')
      ->fields(array('storage_module' => $module, 'storage_active' => 1))
      ->condition('storage_type', $name)
      ->execute();
  }
}

/**
 * Helper function to get the default value for a field on an object.
 *
 * @param $obj_type
 *   The type of $object; e.g. 'node' or 'user'.
 * @param $object
 *   The object for the operation.
 * @param $field
 *   The field structure.
 * @param $instance
 *   The instance structure.
 * @param $langcode
 *   The field language to fill-in with the default value.
 */
function field_get_default_value($obj_type, $object, $field, $instance, $langcode = NULL) {
  $items = array();
  if (!empty($instance['default_value_function'])) {
    $function = $instance['default_value_function'];
    if (function_exists($function)) {
      $items = $function($obj_type, $object, $field, $instance, $langcode);
    }
  }
  elseif (!empty($instance['default_value'])) {
    $items = $instance['default_value'];
  }
  return $items;
}

/**
 * Helper function to filter out empty values.
 *
 * On order to keep marker rows in the database, the function ensures
 * that the right number of 'all columns NULL' values is kept.
 *
 * @param array $field
 * @param array $items
 * @return array
 *   returns filtered and adjusted item array
 *
 * TODO D7: poorly named...
 */
function field_set_empty($field, $items) {
  $function = $field['module'] . '_field_is_empty';
  // We ensure the function is loaded, but explicitly break if it is missing.
  function_exists($function);
  foreach ((array) $items as $delta => $item) {
    if ($function($item, $field)) {
      unset($items[$delta]);
    }
  }
  return array_values($items);
}

/**
 * Helper function to sort items in a field according to
 * user drag-n-drop reordering.
 */
function _field_sort_items($field, $items) {
  if (($field['cardinality'] > 1 || $field['cardinality'] == FIELD_CARDINALITY_UNLIMITED) && isset($items[0]['_weight'])) {
    usort($items, '_field_sort_items_helper');
    foreach ($items as $delta => $item) {
      if (is_array($items[$delta])) {
        unset($items[$delta]['_weight']);
      }
    }
  }
  return $items;
}

/**
 * Sort function for items order.
 * (copied form element_sort(), which acts on #weight keys)
 */
function _field_sort_items_helper($a, $b) {
  $a_weight = (is_array($a) && isset($a['_weight'])) ? $a['_weight'] : 0;
  $b_weight = (is_array($b) && isset($b['_weight'])) ? $b['_weight'] : 0;
  if ($a_weight == $b_weight) {
    return 0;
  }
  return ($a_weight < $b_weight) ? -1 : 1;
}

/**
 * Same as above, using ['_weight']['#value']
 */
function _field_sort_items_value_helper($a, $b) {
  $a_weight = (is_array($a) && isset($a['_weight']['#value'])) ? $a['_weight']['#value'] : 0;
  $b_weight = (is_array($b) && isset($b['_weight']['#value'])) ? $b['_weight']['#value'] : 0;
  if ($a_weight == $b_weight) {
    return 0;
  }
  return ($a_weight < $b_weight) ? -1 : 1;
}

/**
 * Registry of available build modes.
 */
function field_build_modes($obj_type) {
  $info = &drupal_static(__FUNCTION__, array());

  if (!isset($info[$obj_type])) {
    $info[$obj_type] = module_invoke_all('field_build_modes', $obj_type);
  }
  return $info[$obj_type];
}

/**
 * Registry of pseudo-field components in a given bundle.
 *
 * @param $bundle_name
 *   The bundle name.
 * @return
 *   The array of pseudo-field elements in the bundle.
 */
function field_extra_fields($bundle_name) {
  $info = &drupal_static(__FUNCTION__, array());

  if (empty($info)) {
    $info = array();
    $bundles = field_info_bundles();
    foreach ($bundles as $bundle => $bundle_label) {
      // Gather information about non-field object additions.
      $extra = module_invoke_all('field_extra_fields', $bundle);
      drupal_alter('field_extra_fields', $extra, $bundle);

      // Add saved weights.
      foreach (variable_get("field_extra_weights_$bundle", array()) as $key => $value) {
        // Some stored entries might not exist anymore, for instance if uploads
        // have been disabled or vocabularies were deleted.
        if (isset($extra[$key])) {
          $extra[$key]['weight'] = $value;
        }
      }
      $info[$bundle] = $extra;
    }
  }
  if (array_key_exists($bundle_name, $info)) {
    return $info[$bundle_name];
  }
  else {
    return array();
  }
}

/**
 * Pre-render callback to adjust weights of non-field elements on objects.
 */
function _field_extra_weights_pre_render($elements) {
  if (isset($elements['#extra_fields'])) {
    foreach ($elements['#extra_fields'] as $key => $value) {
      // Some core 'fields' use a different key in node forms and in 'view'
      // render arrays. Ensure that we are not on a form first.
      if (!isset($elements['#build_id']) && isset($value['view']) && isset($elements[$value['view']])) {
        $elements[$value['view']]['#weight'] = $value['weight'];
      }
      elseif (isset($elements[$key])) {
        $elements[$key]['#weight'] = $value['weight'];
      }
    }
  }
  return $elements;
}

/**
 * Clear the cached information; called in several places when field
 * information is changed.
 */
function field_cache_clear($rebuild_schema = FALSE) {
  cache_clear_all('*', 'cache_field', TRUE);

  module_load_include('inc', 'field', 'field.info');
  field_info_cache_clear();

  // Refresh the schema to pick up new information.
  // TODO : if db storage gets abstracted out, we'll need to revisit how and when
  // we refresh the schema...
  if ($rebuild_schema) {
    $schema = drupal_get_schema(NULL, TRUE);
  }
}

/**
 * Like filter_xss_admin(), 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 check_plain() is not acceptable).
 */
function field_filter_xss($string) {
  return filter_xss($string, _field_filter_xss_allowed_tags());
}

/**
 * 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');
}

/**
 * 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()) . '>';
}

/**
 * Format a field item for display.
 *
 * TODO D7 : do we still need field_format ?
 * - backwards compatibility of templates - check what fallbacks we can propose...
 * - was used by Views integration in CCK in D6 - do we need now?
 * At least needs a little rehaul/update...
 *
 * Used to display a field's values outside the context of the $node, as
 * when fields are displayed in Views, or to display a field in a template
 * using a different formatter than the one set up on the Display Fields tab
 * for the node's context.
 *
 * @param $field
 *   Either a field array or the name of the field.
 * @param $item
 *   The field item(s) to be formatted (such as $node->field_foo[0],
 *   or $node->field_foo if the formatter handles multiple values itself)
 * @param $formatter_type
 *   The name of the formatter type to use.
 * @param $node
 *   Optionally, the containing node object for context purposes and
 *   field-instance options.
 *
 * @return
 *   A string containing the contents of the field item(s) sanitized for display.
 *   It will have been passed through the necessary check_plain() or check_markup()
 *   functions as necessary.
 */
function field_format($obj_type, $object, $field, $item, $formatter_type = NULL, $formatter_settings = array()) {
  if (!is_array($field)) {
    $field = field_info_field($field);
  }

  if (field_access('view', $field, $obj_type, $object)) {
    $field_type = field_info_field_types($field['type']);

    // We need $field, $instance, $obj_type, $object to be able to display a value...
    list(, , $bundle) = field_extract_ids($obj_type, $object);
    $instance = field_info_instance($obj_type, $field['field_name'], $bundle);

    $display = array(
      'type' => $formatter_type ? $formatter_type : $field_type['default_formatter'],
      'settings' => $formatter_settings,
    );
    $display['settings'] += field_info_formatter_settings($display['type']);

    if ($display['type'] !== 'hidden') {
      $theme = $formatter['module'] . '_formatter_' . $display['type'];

      $element = array(
        '#theme' => $theme,
        '#field_name' => $field['field_name'],
        '#object_type' => $obj_type,
        '#bundle' => $bundle,
        '#formatter' => $display['type'],
        '#settings' => $display['settings'],
        '#object' => $object,
        '#object_type' => $obj_type,
        '#delta' => isset($item['#delta']) ? $item['#delta'] : NULL,
      );

      if (field_behaviors_formatter('multiple values', $display) == FIELD_BEHAVIOR_DEFAULT) {
        // Single value formatter.

        // hook_field('sanitize') expects an array of items, so we build one.
        $items = array($item);
        $function = $field['module'] . '_field_sanitize';
        if (function_exists($function)) {
          $function($obj_type, $object, $field, $instance, $items);
        }

        $element['#item'] = $items[0];
      }
      else {
        // Multiple values formatter.
        $items = $item;
        $function = $field['module'] . '_field_sanitize';
        if (function_exists($function)) {
          $function($obj_type, $object, $field, $instance, $items);
        }

        foreach ($items as $delta => $item) {
          $element[$delta] = array(
            '#item' => $item,
            '#weight' => $delta,
          );
        }
      }

      return theme($theme, $element);
    }
  }
}

/**
 * Return a single field, fully themed with label and multiple values.
 *
 * To be used by third-party code (Views, Panels...) that needs to output
 * an isolated field. Do *not* use inside node templates, use
 * render($content[FIELD_NAME]) instead.
 *
 * The field will be displayed using the display options (label display,
 * formatter settings...) specified in the $instance structure for the given
 * build mode: $instance['display'][$build_mode].
 *
 * @param $object
 *   The object containing the field to display. Must at least contain the id key,
 *   revision key (if applicable), bundle key, and the field data.
 * @param $field
 *   The field structure.
 * @param $instance
 *   The instance structure for $field on $object's bundle.
 * @param $build_mode
 *   Build mode, e.g. 'full', 'teaser'...
 * @return
 *   The themed output for the field.
 */
function field_view_field($obj_type, $object, $field, $instance, $build_mode = 'full') {
  $output = '';
  if (isset($object->$field['field_name'])) {
    $items = $object->$field['field_name'];

    // One-field equivalent to _field_invoke('sanitize').
    $function = $field['module'] . '_field_sanitize';
    if (function_exists($function)) {
      $function($obj_type, $object, $field, $instance, $items);
      $object->$field['field_name'] = $items;
    }

    $view = field_default_view($obj_type, $object, $field, $instance, $items, $build_mode);
    // TODO : what about hook_field_attach_view ?

    $output = $view[$field['field_name']];
  }
  return $output;
}

/**
 * Determine whether a field has any data.
 *
 * @param $field
 *   A field structure.
 * @return
 *   TRUE if the field has data for any object; FALSE otherwise.
 */
function field_has_data($field) {
  $results = field_attach_query($field['id'], array(), 1);
  return !empty($results);
}

/**
 * Determine whether the user has access to a given field.
 *
 * @param $op
 *   The operation to be performed. Possible values:
 *   - "edit"
 *   - "view"
 * @param $field
 *   The field on which the operation is to be performed.
 * @param $obj_type
 *   The type of $object; e.g. 'node' or 'user'.
 * @param $object
 *   (optional) The object for the operation.
 * @param $account
 *   (optional) The account to check, if not given use currently logged in user.
 * @return
 *   TRUE if the operation is allowed;
 *   FALSE if the operation is denied.
 */
function field_access($op, $field, $obj_type, $object = NULL, $account = NULL) {
  global $user;

  if (is_null($account)) {
    $account = $user;
  }

  $field_access = module_invoke_all('field_access', $op, $field, $obj_type, $object, $account);
  foreach ($field_access as $value) {
    if ($value === FALSE) {
      return FALSE;
    }
  }
  return TRUE;
}

/**
 * Helper function to extract id, vid, and bundle name from an object.
 *
 * @param $obj_type
 *   The type of $object; e.g. 'node' or 'user'.
 * @param $object
 *   The object from which to extract values.
 * @return
 *   A numerically indexed array (not a hash table) containing these
 *   elements:
 *
 *   0: primary id of the object
 *   1: revision id of the object, or NULL if $obj_type is not versioned
 *   2: bundle name of the object
 *   3: whether $obj_type's fields should be cached (TRUE/FALSE)
 */
function field_extract_ids($obj_type, $object) {
  // TODO D7 : prevent against broken 3rd party $node without 'type'.
  $info = field_info_fieldable_types($obj_type);
  // Objects being created might not have id/vid yet.
  $id = isset($object->{$info['object keys']['id']}) ? $object->{$info['object keys']['id']} : NULL;
  $vid = ($info['object keys']['revision'] && isset($object->{$info['object keys']['revision']})) ? $object->{$info['object keys']['revision']} : NULL;
  // If no bundle key provided, then we assume a single bundle, named after the
  // type of the object.
  $bundle = $info['object keys']['bundle'] ? $object->{$info['object keys']['bundle']} : $obj_type;
  $cacheable = $info['cacheable'];
  return array($id, $vid, $bundle, $cacheable);
}

/**
 * Helper function to extract id, vid, and bundle name from an object.
 *
 * @param $obj_type
 *   The type of $object; e.g. 'node' or 'user'.
 * @param $bundle
 *   The bundle object (or string if bundles for this object type do not exist
 *   as standalone objects).
 * @return
 *   The bundle name.
 */
function field_extract_bundle($obj_type, $bundle) {
  if (is_string($bundle)) {
    return $bundle;
  }

  $info = field_info_fieldable_types($obj_type);
  if (is_object($bundle) && isset($info['bundle keys']['bundle']) && isset($bundle->{$info['bundle keys']['bundle']})) {
    return $bundle->{$info['bundle keys']['bundle']};
  }
}

/**
 * Helper function to assemble an object structure with initial ids.
 *
 * This function can be seen as reciprocal to field_extract_ids().
 *
 * @param $obj_type
 *   The type of $object; e.g. 'node' or 'user'.
 * @param $ids
 *   A numerically indexed array, as returned by field_extract_ids(),
 *   containing these elements:
 *   0: primary id of the object
 *   1: revision id of the object, or NULL if $obj_type is not versioned
 *   2: bundle name of the object
 * @return
 *   An $object structure, initialized with the ids provided.
 */
function field_create_stub_entity($obj_type, $ids) {
  $object = new stdClass();
  $info = field_info_fieldable_types($obj_type);
  $object->{$info['object keys']['id']} = $ids[0];
  if (isset($info['object keys']['revision']) && !is_null($ids[1])) {
    $object->{$info['object keys']['revision']} = $ids[1];
  }
  if ($info['object keys']['bundle']) {
    $object->{$info['object keys']['bundle']} = $ids[2];
  }
  return $object;
}

/**
 * Theme preprocess function for field.tpl.php.
 *
 * @see field.tpl.php
 */
function template_preprocess_field(&$variables) {
  $element = $variables['element'];
  list(, , $bundle) = field_extract_ids($element['#object_type'], $element['#object']);
  $instance = field_info_instance($element['#object_type'], $element['#field_name'], $bundle);
  $field = field_info_field($element['#field_name']);

  $field_type_css = strtr($field['type'], '_', '-');
  $field_name_css = strtr($field['field_name'], '_', '-');

  // If the formatter is multiple, the template sees only one 'item', which
  // will include all values.
  $items = $element['#formatter_single'] ? $element['items'] : array($element['items']);

  $additions = array(
    'object' => $element['#object'],
    'field' => $field,
    'instance' => $instance,
    'build_mode' => $element['#build_mode'],
    'items' => $items,
    'field_type' => $field['type'],
    'field_name' => $field['field_name'],
    'field_type_css' => $field_type_css,
    'field_name_css' => $field_name_css,
    'label' => $element['#title'],
    'label_display' => $element['#label_display'],
    'label_hidden' => $element['#label_display'] == 'hidden',
    'field_language' => $element['#language'],
    'field_translatable' => $field['translatable'],
    'classes_array' => array(
      'field-name-' . $field_name_css,
      'field-type-' . $field_type_css,
      'field-label-' . $element['#label_display'],
    ),
    'template_files' => array(
      'field',
      'field-' . $element['#field_name'],
      'field-' . $bundle,
      'field-' . $element['#field_name'] . '-' . $bundle,
    ),
  );
  $variables = array_merge($variables, $additions);

  // Initialize attributes for each item.
  foreach ($variables['items'] as $delta => $item) {
    $variables['item_attributes_array'][$delta] = array();
  }
}

/**
 * Theme process function for field.tpl.php.
 *
 * @see field.tpl.php
 */
function template_process_field(&$variables) {
  // Flatten out attributes for each item.
  foreach ($variables['items'] as $delta => $item) {
    $variables['item_attributes'][$delta] = drupal_attributes($variables['item_attributes_array'][$delta]);
  }
}
/**
 * @} End of "defgroup field"
 */