content.module

<?php
// $Id$
/**
 * @file
 * Allows administrators to associate custom fields to content types.
 */

define('CONTENT_DB_STORAGE_PER_FIELD', 0);
define('CONTENT_DB_STORAGE_PER_CONTENT_TYPE', 1);

define('CONTENT_CALLBACK_NONE', 0x0001);
define('CONTENT_CALLBACK_DEFAULT', 0x0002);
define('CONTENT_CALLBACK_CUSTOM', 0x0004);

define('CONTENT_HANDLE_CORE', 0x0001);
define('CONTENT_HANDLE_MODULE', 0x0002);

function content_help($path, $arg) {
  switch ($path) {
    case 'admin/help#content':
      $output = '<p>'. t('The content module, a required component of the Content Construction Kit (CCK), allows administrators to associate custom fields with content types. In Drupal, content types are used to define the characteristics of a post, including the title and description of the fields displayed on its add and edit pages. Using the content module (and the other helper modules included in CCK), custom fields beyond the default "Title" and "Body" may be added. CCK features are accessible through tabs on the <a href="@content-types">content types administration page</a>. (See the <a href="@node-help">node module help page</a> for more information about content types.)', array('@content-types' => url('admin/content/types'), '@node-help' => url('admin/help/node'))) .'</p>';
      $output .= '<p>'. t('When adding a custom field to a content type, you determine its type (whether it will contain text, numbers, or references to other objects) and how it will be displayed (either as a text field or area, a select box, checkbox, radio button, or autocompleting field). A field may have multiple values (i.e., a "person" may have multiple e-mail addresses) or a single value (i.e., an "employee" has a single employee identification number). As you add and edit fields, CCK automatically adjusts the structure of the database as necessary. CCK also provides a number of other features, including intelligent caching for your custom data, an import and export facility for content type definitions, and integration with other contributed modules.') .'</p>';
      $output .= '<p>'. t('Custom field types are provided by a set of optional modules included with CCK (each module provides a different type). The <a href="@modules">modules page</a> allows you to enable or disable CCK components. A default installation of CCK includes:', array('@modules' => url('admin/build/modules'))) .'</p>';
      $output .= '<ul>';
      $output .= '<li>'. t('<em>number</em>, which adds numeric field types, in integer, decimal or floating point form. You may define a set of allowed inputs, or specify an allowable range of values. A variety of common formats for displaying numeric data are available.') .'</li>';
      $output .= '<li>'. t("<em>text</em>, which adds text field types. A text field may contain plain text only, or optionally, may use Drupal's input format filters to securely manage rich text input. Text input fields may be either a single line (text field), multiple lines (text area), or for greater input control, a select box, checkbox, or radio buttons. If desired, CCK can validate the input to a set of allowed values.") .'</li>';
      $output .= '<li>'. t('<em>nodereference</em>, which creates custom references between Drupal nodes. By adding a <em>nodereference</em> field and two different content types, for instance, you can easily create complex parent/child relationships between data (multiple "employee" nodes may contain a <em>nodereference</em> field linking to an "employer" node).') .'</li>';
      $output .= '<li>'. t('<em>userreference</em>, which creates custom references to your sites\' user accounts. By adding a <em>userreference</em> field, you can create complex relationships between your site\'s users and posts. To track user involvement in a post beyond Drupal\'s standard <em>Authored by</em> field, for instance, add a <em>userreference</em> field named "Edited by" to a content type to store a link to an editor\'s user account page.') .'</li>';
      $output .= '<li>'. t('<em>fieldgroup</em>, which creates collapsible fieldsets to hold a group of related fields. A fieldset may either be open or closed by default. The order of your fieldsets, and the order of fields within a fieldset, is managed via a drag-and-drop interface provided by content module.') .'</li>';
      $output .= '</ul>';
      $output .= '<p>'. t('For more information, see the online handbook entry for <a href="@handbook-cck">CCK</a> or the <a href="@project-cck">CCK project page</a>.', array('@handbook-cck' => 'http://drupal.org/handbook/modules/cck', '@project-cck' => 'http://drupal.org/project/cck')) .'</p>';
      return $output;
  }
}

/**
 * Implementation of hook_flush_caches.
 */
function content_flush_caches() {
  return array(content_cache_tablename());
}

/**
 * Implementation of hook_init().
 */
function content_init() {
  drupal_add_css(drupal_get_path('module', 'content') .'/theme/content-module.css');
  if (module_exists('token') && !function_exists('content_token_values')) {
    module_load_include('inc', 'content', 'includes/content.token');
  }
  if (module_exists('diff') && !function_exists('content_diff')) {
    module_load_include('inc', 'content', 'includes/content.diff');
  }
  if (module_exists('panels')) {
    module_load_include('inc', 'content', 'includes/content.panels');
  }
}

/**
 * Implementation of hook_perm().
 */
function content_perm() {
  return array('Use PHP input for field settings (dangerous - grant with care)');
}

/**
 * Implementation of hook_menu_alter().
 */
function content_menu_alter(&$items) {
  // Customize the content types page with our own callback
  $items['admin/content/types']['page callback'] = 'content_types_overview';
  $items['admin/content/types']['file'] = 'content.admin.inc';
  $items['admin/content/types']['file path'] = drupal_get_path('module', 'content') .'/includes';
}

/**
 * Implementation of hook_menu().
 */
function content_menu() {
  $items = array();
  $items['admin/content/types/fields'] = array(
    'title' => 'Fields',
    'page callback' => 'content_fields_list',
    'access arguments' => array('administer content types'),
    'file' => 'includes/content.admin.inc',
    'type' => MENU_LOCAL_TASK,
  );
  // Callback for AHAH add more buttons.
  $items['content/js_add_more'] = array(
    'page callback' => 'content_add_more_js',
    'access arguments' => array('access content'),
    'file' => 'includes/content.node_form.inc',
    'type' => MENU_CALLBACK,
  );

  // Make sure this doesn't fire until content_types is working,
  // and tables are updated, needed to avoid errors on initial installation.
  if (!defined('MAINTENANCE_MODE') && variable_get('content_schema_version', -1) >= 6007) {
    foreach (node_get_types() as $type) {
      $type_name = $type->type;
      $content_type = content_types($type_name);
      $type_url_str = $content_type['url_str'];
      $items['admin/content/node-type/'. $type_url_str .'/fields'] = array(
        'title' => 'Manage fields',
        'page callback' => 'drupal_get_form',
        'page arguments' => array('content_field_overview_form', $type_name),
        'access arguments' => array('administer content types'),
        'file' => 'includes/content.admin.inc',
        'type' => MENU_LOCAL_TASK,
        'weight' => 1,
      );
      $items['admin/content/node-type/'. $type_url_str .'/display'] = array(
        'title' => 'Display fields',
        'page callback' => 'drupal_get_form',
        'page arguments' => array('content_display_overview_form', $type_name),
        'access arguments' => array('administer content types'),
        'file' => 'includes/content.admin.inc',
        'type' => MENU_LOCAL_TASK,
        'weight' => 2,
      );
      $contexts = content_build_modes('_tabs');
      foreach ($contexts as $key => $tab) {
        $items['admin/content/node-type/'. $type_url_str .'/display/'. $key] = array(
          'title' => $tab['title'],
          'page arguments' => array('content_display_overview_form', $type_name, $key),
          'access arguments' => array('administer content types'),
          'type' => $key == 'basic' ? MENU_DEFAULT_LOCAL_TASK : MENU_LOCAL_TASK,
          'weight' => $key == 'basic' ? 0 : 1,
        );
      }
      // Cast as an array in case this is called before any fields have
      // been added, like when a new content type is created.
      foreach ((array) $content_type['fields'] as $field) {
        $field_name = $field['field_name'];
        $items['admin/content/node-type/'. $type_url_str .'/fields/'. $field_name] = array(
          'title' => $field['widget']['label'],
          'page callback' => 'drupal_get_form',
          'page arguments' => array('content_field_edit_form', $type_name, $field_name),
          'access arguments' => array('administer content types'),
          'file' => 'includes/content.admin.inc',
          'type' => MENU_LOCAL_TASK,
        );
        $items['admin/content/node-type/'. $type_url_str .'/fields/'. $field_name .'/remove'] = array(
          'title' => 'Remove field',
          'page callback' => 'drupal_get_form',
          'page arguments' => array('content_field_remove_form', $type_name, $field_name),
          'access arguments' => array('administer content types'),
          'file' => 'includes/content.admin.inc',
          'type' => MENU_CALLBACK,
        );
      }
    }
  }
  return $items;
}

/**
 * Hook elements().
 *
 * Used to add multiple value processing, validation, and themes.
 *
 * FAPI callbacks can be declared here, and the element will be
 * passed to those callbacks.
 *
 * Drupal will automatically theme the element using a theme with
 * the same name as the hook_elements key.
 */
function content_elements() {
  return array(
    'content_multiple_values' => array(),
    'content_field' => array(),
  );
}

/**
 * Implementation of hook_theme().
 */
function content_theme() {
  $path = drupal_get_path('module', 'content') .'/theme';
  require_once "./$path/theme.inc";

  return array(
    'content_field' => array(
      'template' => 'content-field',
      'arguments' => array('element' => NULL),
      'path' => $path,
    ),
    'content_overview_links' => array(
      'arguments' => array(),
    ),
    'content_field_overview_form' => array(
      'template' => 'content-admin-field-overview-form',
      'file' => 'theme.inc',
      'path' => $path,
      'arguments' => array('form' => NULL),
    ),
    'content_display_overview_form' => array(
      'template' => 'content-admin-display-overview-form',
      'file' => 'theme.inc',
      'path' => $path,
      'arguments' => array('form' => NULL),
    ),
    'content_exclude' => array(
      'arguments' => array('content' => NULL, 'object' => array(), 'context' => NULL),
    ),
    'content_view_multiple_field' => array(
      'arguments' => array('items' => NULL, 'field' => NULL, 'data' => NULL),
    ),
    'content_multiple_values' => array(
      'arguments' => array('element' => NULL),
    ),
  );
}

/**
 * Implementation of hook_views_api().
 */
function content_views_api() {
  return array(
    'api' => 2,
    'path' => drupal_get_path('module', 'content') . '/includes/views',
  );
}

/**
 * Load data for a node type's fields.
 * Implementation of hook_nodeapi 'load' op.
 *
 * When loading one of the content.module nodes, we need to let each field handle
 * its own loading. This can make for a number of queries in some cases, so we
 * cache the loaded object structure and invalidate it during the update process.
 */
function content_load(&$node) {
  $cid = 'content:'. $node->nid .':'. $node->vid;
  if ($cached = cache_get($cid, content_cache_tablename())) {
    foreach ($cached->data as $key => $value) {
      $node->$key = $value;
    }
  }
  else {
    $default_additions = _content_field_invoke_default('load', $node);
    if ($default_additions) {
      foreach ($default_additions as $key => $value) {
        $node->$key = $value;
      }
    }
    $additions = _content_field_invoke('load', $node);
    if ($additions) {
      foreach ($additions as $key => $value) {
        $node->$key = $value;
        $default_additions[$key] = $value;
      }
    }
    cache_set($cid, $default_additions, content_cache_tablename());
  }
}

/**
 * Implementation of hook_nodeapi 'validate' op.
 *
 */
function content_validate(&$node, $form = NULL) {
  _content_field_invoke('validate', $node, $form);
  _content_field_invoke_default('validate', $node, $form);
}

/**
 * Implementation of hook_nodeapi 'presave' op.
 *
 */
function content_presave(&$node) {
  _content_field_invoke('presave', $node);
  _content_field_invoke_default('presave', $node);
}

/**
 * Implementation of hook_nodeapi 'insert' op.
 *
 * Insert node type fields.
 */
function content_insert(&$node) {
  _content_field_invoke('insert', $node);
  _content_field_invoke_default('insert', $node);
}

/**
 * Implementation of hook_nodeapi 'update' op.
 *
 * Update node type fields.
 */
function content_update(&$node) {
  _content_field_invoke('update', $node);
  _content_field_invoke_default('update', $node);
  cache_clear_all('content:'. $node->nid .':'. $node->vid, content_cache_tablename());
}

/**
 * Implementation of hook_nodeapi 'delete' op.
 *
 * Delete node type fields.
 */
function content_delete(&$node) {
  _content_field_invoke('delete', $node);
  _content_field_invoke_default('delete', $node);
  cache_clear_all('content:'. $node->nid .':', content_cache_tablename(), TRUE);
}

/**
 * Implementation of hook_nodeapi 'delete_revision' op.
 *
 * Delete node type fields for a revision.
 */
function content_delete_revision(&$node) {
  _content_field_invoke('delete revision', $node);
  _content_field_invoke_default('delete revision', $node);
  cache_clear_all('content:'. $node->nid .':'. $node->vid, content_cache_tablename());
}

/**
 * Implementation of hook_nodeapi 'view' op.
 *
 * Generate field render arrays.
 */
function content_view(&$node, $teaser = FALSE, $page = FALSE) {
  // Let field modules sanitize their data for output.
  _content_field_invoke('sanitize', $node, $teaser, $page);

  // Merge fields.
  $additions = _content_field_invoke_default('view', $node, $teaser, $page);
  $node->content = array_merge((array) $node->content, $additions);
}

/**
 * Render 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 the
 * $FIELD_NAME_rendered variables instead.
 *
 * By default, the field is displayed using the settings defined for the
 * 'full node' or 'teaser' contexts (depending on the value of the $teaser param).
 * Set $node->build_mode to a different value to use a different context.
 *
 * Different settings can be specified by adjusting $field['display_settings'].
 *
 * @param $field
 *   The field definition.
 * @param $node
 *   The node containing the field to display. Can be a 'pseudo-node', containing
 *   at least 'type', 'nid', 'vid', and the field data.
 * @param $teaser
 * @param $page
 *   Similar to hook_nodeapi('view')
 * @return
 *   The themed output for the field.
 */
function content_view_field($field, $node, $teaser = FALSE, $page = FALSE) {
  $output = '';
  if (isset($node->$field['field_name'])) {
    $items = $node->$field['field_name'];

    // Use 'full'/'teaser' if not specified otherwise.
    $node->build_mode = isset($node->build_mode) ? $node->build_mode : NODE_BUILD_NORMAL;

    // One-field equivalent to _content_field_invoke('sanitize').
    $field_types = _content_field_types();
    $module = $field_types[$field['type']]['module'];
    $function = $module .'_field';
    if (function_exists($function)) {
      $function('sanitize', $node, $field, $items, $teaser, $page);
      $node->$field['field_name'] = $items;
    }

    $view = content_field('view', $node, $field, $items, $teaser, $page);
    // content_field('view') adds a wrapper to handle variables and 'excluded'
    // fields for node templates. We bypass it and render the actual field.
    $output = drupal_render($view[$field['field_name']]['field']);
  }
  return $output;
}

/**
 * Implementation of hook_nodeapi 'alter' op.
 *
 * Add back the formatted values in the 'view' element for all fields,
 * so that node templates can use it.
 */
function content_alter(&$node, $teaser = FALSE, $page = FALSE) {
  _content_field_invoke_default('alter', $node, $teaser, $page);
}

/**
 * Implementation of hook_nodeapi 'prepare translation' op.
 *
 * Generate field render arrays.
 */
function content_prepare_translation(&$node) {
  $default_additions = _content_field_invoke_default('prepare translation', $node);
  $additions = _content_field_invoke('prepare translation', $node);
  // Merge module additions after the default ones to enable overriding
  // of field values.
  $node = (object) array_merge((array) $node, $default_additions, $additions);
}

/**
 * Implementation of hook_nodeapi().
 */
function content_nodeapi(&$node, $op, $a3 = NULL, $a4 = NULL) {
  // Prevent against invalid 'nodes' built by broken 3rd party code.
  if (isset($node->type)) {
    $type = content_types($node->type);
    // Save cycles if the type has no CCK fields.
    if (!empty($type['fields'])) {
      $callback = 'content_'. str_replace(' ', '_', $op);
      if (function_exists($callback)) {
        $callback($node, $a3, $a4);
      }
    }

    // Special case for 'view' op, we want to adjust weights of non-cck fields
    // even if there are no actual fields for this type.
    if ($op == 'view') {
      foreach ($type['extra'] as $key => $value) {
        // Some core 'fields' use a different key in node forms and in 'view'
        // render arrays.
        if (isset($value['view']) && isset($node->content[$value['view']])) {
          $node->content[$value['view']]['#weight'] = $value['weight'];
        }
        elseif (isset($node->content[$key])) {
          $node->content[$key]['#weight'] = $value['weight'];
        }
      }
    }
  }
}

/**
 *  Implementation of hook_form_alter().
 */
function content_form_alter(&$form, $form_state, $form_id) {
  if (isset($form['type']) && isset($form['#node']) && $form['type']['#value'] .'_node_form' == $form_id) {
    $type = content_types($form['#node']->type);
    if (!empty($type['fields'])) {
      module_load_include('inc', 'content', 'includes/content.node_form');
      // Merge field widgets.
      $form = array_merge($form, content_form($form, $form_state));
    }
    // Adjust weights for non-CCK fields.
    foreach ($type['extra'] as $key => $value) {
      if (isset($form[$key])) {
        $form[$key]['#weight'] = $value['weight'];
      }
    }
  }
}

/**
 * Proxy function to call content_add_more_submit(), because it might not be
 * included yet when the form is processed and invokes the callback.
 */
function content_add_more_submit_proxy($form, &$form_state) {
  module_load_include('inc', 'content', 'includes/content.node_form');
  content_add_more_submit($form, $form_state);
}

/**
 * Theme an individual form element.
 *
 * Combine multiple values into a table with drag-n-drop reordering.
 */
function theme_content_multiple_values($element) {
  $field_name = $element['#field_name'];
  $field = content_fields($field_name);
  $output = '';

  if ($field['multiple'] >= 1) {
    $table_id = $element['#field_name'] .'_values';
    $order_class = $element['#field_name'] .'-delta-order';
    $required = !empty($element['#required']) ? '<span class="form-required" title="'. t('This field is required.') .'">*</span>' : '';

    $header = array(
      array(
        'data' => t('!title: !required', array('!title' => $element['#title'], '!required' => $required)),
        'colspan' => 2
      ),
      t('Order'),
    );
    $rows = array();

    // Sort items according to '_weight' (needed when the form comes back after
    // preview or failed validation)
    $items = array();
    foreach (element_children($element) as $key) {
      if ($key !== $element['#field_name'] .'_add_more') {
        $items[] = &$element[$key];
      }
    }
    usort($items, '_content_sort_items_value_helper');

    // Add the items as table rows.
    foreach ($items as $key => $item) {
      $item['_weight']['#attributes']['class'] = $order_class;
      $delta_element = drupal_render($item['_weight']);
      $cells = array(
        array('data' => '', 'class' => 'content-multiple-drag'),
        drupal_render($item),
        array('data' => $delta_element, 'class' => 'delta-order'),
      );
      $rows[] = array(
        'data' => $cells,
        'class' => 'draggable',
      );
    }

    $output .= theme('table', $header, $rows, array('id' => $table_id, 'class' => 'content-multiple-table'));
    $output .= $element['#description'] ? '<div class="description">'. $element['#description'] .'</div>' : '';
    $output .= drupal_render($element[$element['#field_name'] .'_add_more']);

    drupal_add_tabledrag($table_id, 'order', 'sibling', $order_class);
  }
  else {
    foreach (element_children($element) as $key) {
      $output .= drupal_render($element[$key]);
    }
  }

  return $output;
}

/**
 * Modules notify Content module when uninstalled, disabled, etc.
 *
 * @param string $op
 *   the module operation: uninstall, install, enable, disable
 * @param string $module
 *   the name of the affected module.
 * @TODO
 *   figure out exactly what needs to be done by content module when
 *   field modules are installed, uninstalled, enabled or disabled.
 */
function content_notify($op, $module) {
  switch ($op) {
    case 'install':
      content_clear_type_cache();
      break;
    case 'uninstall':
      module_load_include('inc', 'content', 'includes/content.crud');
      content_module_delete($module);
      break;
    case 'enable':
      content_associate_fields($module);
      content_clear_type_cache();
      break;
    case 'disable':
      // When CCK modules are disabled before content module's update is run
      // to add the active column, we can't do this.
      if (variable_get('content_schema_version', -1) < 6007) {
        return FALSE;
      }
      db_query("UPDATE {". content_field_tablename() ."} SET active=0 WHERE module='%s'", $module);
      db_query("UPDATE {". content_instance_tablename() ."} SET widget_active=0 WHERE widget_module='%s'", $module);
      content_clear_type_cache(TRUE);
      break;
  }
}

/**
 * Allows a module to update the database for fields and columns it controls.
 *
 * @param string $module
 *   The name of the module to update on.
 */
function content_associate_fields($module) {
  // When CCK modules are enabled before content module's update is run,
  // to add module and active columns, we can't do this.
  if (variable_get('content_schema_version', -1) < 6007) {
    return FALSE;
  }
  $module_fields = module_invoke($module, 'field_info');
  if ($module_fields) {
    foreach ($module_fields as $name => $field_info) {
      watchdog('content', 'Updating field type %type with module %module.', array('%type' => $name, '%module' => $module));
      db_query("UPDATE {". content_field_tablename() ."} SET module = '%s', active = %d WHERE type = '%s'", $module, 1, $name);
    }
  }
  $module_widgets = module_invoke($module, 'widget_info');
  if ($module_widgets) {
    foreach ($module_widgets as $name => $widget_info) {
      watchdog('content', 'Updating widget type %type with module %module.', array('%type' => $name, '%module' => $module));
      db_query("UPDATE {". content_instance_tablename() ."} SET widget_module = '%s', widget_active = %d WHERE widget_type = '%s'", $module, 1, $name);
    }
  }
  // This is called from updates and installs, so get the install-safe
  // version of a fields array.
  $fields_set = array();
  module_load_include('install', 'content');
  $types = content_types_install();
  foreach ($types as $type_name => $fields) {
    foreach ($fields as $field) {
      if ($field['module'] == $module && !in_array($field['field_name'], $fields_set)) {
        $columns = module_invoke($field['module'], 'field_settings', 'database columns', $field);
        db_query("UPDATE {". content_field_tablename() ."} SET db_columns = '%s' WHERE field_name = '%s'", serialize($columns), $field['field_name']);
        $fields_set[] = $field['field_name'];
      }
    }
  }
}

/**
 * Implementation of hook_field(). Handles common field housekeeping.
 *
 * This implementation is special, as content.module does not define any field
 * types. Instead, this function gets called after the type-specific hook, and
 * takes care of default stuff common to all field types.
 *
 * Db-storage ops ('load', 'insert', 'update', 'delete', 'delete revisions')
 * are not executed field by field, and are thus handled separately in
 * content_storage.
 *
 * The 'view' operation constructs the $node in a way that you can use
 * drupal_render() to display the formatted output for an individual field.
 * i.e. print drupal_render($node->countent['field_foo']);
 *
 * The code now supports both single value formatters, which theme an
 * individual item value as has been done in previous version of CCK,
 * and multiple value formatters, which theme all values for the field
 * in a single theme. The multiple value formatters could be used, for
 * instance, to plot field values on a single map or display them
 * in a graph. Single value formatters are the default, multiple value
 * formatters can be designated as such in formatter_info().
 *
 * The node array will look like:
 *   $node->content['field_foo']['wrapper'] = array(
 *     '#type' => 'content_field',
 *     '#title' => 'label'
 *     '#field_name' => 'field_name',
 *     '#node' => $node,
 *     // Value of the $teaser param of hook_nodeapi('view').
 *     '#teaser' => $teaser,
 *     // Value of the $page param of hook_nodeapi('view').
 *     '#page' => $page,
 *     // The curent rendering context ('teaser', 'full', NODE_BUILD_SEARCH_INDEX...).
 *     '#context' => $context,
 *     'items' =>
 *       0 => array(
 *         '#item' => $items[0],
 *         // Only for 'single-value' formatters
 *         '#theme' => $theme,
 *         '#field_name' => 'field_name',
 *         '#type_name' => $node->type,
 *         '#formatter' => $formatter_name,
 *         '#node' => $node,
 *         '#delta' => 0,
 *       ),
 *       1 => array(
 *         '#item' => $items[1],
 *         // Only for 'single-value' formatters
 *         '#theme' => $theme,
 *         '#field_name' => 'field_name',
 *         '#type_name' => $node->type,
 *         '#formatter' => $formatter_name,
 *         '#node' => $node,
 *         '#delta' => 1,
 *       ),
 *       // Only for 'multiple-value' formatters
 *       '#theme' => $theme,
 *       '#field_name' => 'field_name',
 *       '#type_name' => $node->type,
 *       '#formatter' => $formatter_name,
 *     ),
 *   );
 */
function content_field($op, &$node, $field, &$items, $teaser, $page) {
  switch ($op) {
    case 'validate':
      // TODO: here we could validate that the number of multiple data is correct ?
      // We're controlling the number of fields to fill out and saving empty
      // ones if a specified number is requested, so no reason to do any validation
      // here right now, but if later create a method to indicate whether
      // 'required' means all values must be filled out, we can come back
      // here and check that they're not empty.
      break;

    case 'presave':
      if (!empty($node->devel_generate)) {
        include_once('./'. drupal_get_path('module', 'content') .'/includes/content.devel.inc');
        content_generate_fields($node, $field);
        $items = $node->{$field['field_name']};
      }

      // Manual node_save calls might not have all fields filled in.
      // On node insert, we need to make sure all tables get at least an empty
      // record, or subsequent edits, using drupal_write_record() in update mode,
      // won't insert any data.
      // Missing fields on node update are handled in content_storage().
      if (empty($items) && !isset($node->nid)) {
        foreach (array_keys($field['columns']) as $column) {
          $items[0][$column] = NULL;
        }
        $node->$field['field_name'] = $items;
      }

      // If there was an AHAH add more button in this field, don't save it.
      // TODO: is it still needed ?
      unset($items[$field['field_name'] .'_add_more']);

      if (content_handle('widget', 'multiple values', $field) == CONTENT_HANDLE_CORE) {
        // Reorder items to account for drag-n-drop reordering.
        $items = _content_sort_items($field, $items);
      }

      // Filter out empty values.
      $items = content_set_empty($field, $items);

      break;

    case 'view':
      $addition = array();

      // Previewed nodes bypass the 'presave' op, so we need to some massaging.
      if ($node->build_mode == NODE_BUILD_PREVIEW && content_handle('widget', 'multiple values', $field) == CONTENT_HANDLE_CORE) {
        if (content_handle('widget', 'multiple values', $field) == CONTENT_HANDLE_CORE) {
          // Reorder items to account for drag-n-drop reordering.
          $items = _content_sort_items($field, $items);
        }

        // Filter out empty values.
        $items = content_set_empty($field, $items);
      }

      // NODE_BUILD_NORMAL is 0, and ('whatever' == 0) is TRUE, so we need a ===.
      if ($node->build_mode === NODE_BUILD_NORMAL || $node->build_mode == NODE_BUILD_PREVIEW) {
        $context = $teaser ? 'teaser' : 'full';
      }
      else {
        $context = $node->build_mode;
      }
      // The field may be missing info for $contexts added by modules 
      // enabled after the field was last edited.
      $formatter_name = isset($field['display_settings'][$context]) && isset($field['display_settings'][$context]['format']) ? $field['display_settings'][$context]['format'] : 'default';
      if ($formatter = _content_get_formatter($formatter_name, $field['type'])) {
        $theme = $formatter['module'] .'_formatter_'. $formatter_name;
        $single = (content_handle('formatter', 'multiple values', $formatter) == CONTENT_HANDLE_CORE);

        $label_display = isset($field['display_settings']['label']['format']) ? $field['display_settings']['label']['format'] : 'above';
        // Do not include field labels when indexing content.
        if ($context == NODE_BUILD_SEARCH_INDEX) {
          $label_display = 'hidden';
        }

        $element = array(
          '#type' => 'content_field',
          '#title' => check_plain(t($field['widget']['label'])),
          '#field_name' => $field['field_name'],
          '#access' => $formatter_name != 'hidden' && content_access('view', $field),
          '#label_display' => $label_display,
          '#node' => $node,
          '#teaser' => $teaser,
          '#page' => $page,
          '#context' => $context,
          '#single' => $single,
          'items' => array(),
        );

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

        // Append formatter information either on each item ('single-value' formatter)
        // or at the upper 'items' level ('multiple-value' formatter)
        $format_info = array(
          '#theme' => $theme,
          '#field_name' => $field['field_name'],
          '#type_name' => $node->type,
          '#formatter' => $formatter_name,
          '#node' => $node,
        );
        if ($single) {
          foreach ($items as $delta => $item) {
            $element['items'][$delta] += $format_info;
            $element['items'][$delta]['#item']['#delta'] = $delta;
          }
        }
        else {
          $element['items'] += $format_info;
        }

        // The wrapper lets us get the themed output for the whole field
        // to populate the $FIELD_NAME_rendered variable for node templates,
        // and hide it from the $content variable if needed.
        // See 'preprocess_node' op and theme_content_field_wrapper()?
        $wrapper = array(
          'field' => $element,
          '#weight' => $field['widget']['weight'],
          '#post_render' => array('content_field_wrapper_post_render'),
          '#field_name' => $field['field_name'],
          '#type_name' => $node->type,
          '#context' => $context,
        );

        $addition = array($field['field_name'] => $wrapper);
      }
      return $addition;

    case 'alter':
      // Add back the formatted values in the 'view' element,
      // so that tokens and node templates can use it.
      // Note: Doing this in 'preprocess_node' breaks token integration.

      // The location of the field's rendered output depends on whether the
      // field is in a fieldgroup or not.
      $wrapper = NULL;
      if (isset($node->content[$field['field_name']])) {
        $wrapper = $node->content[$field['field_name']];
      }
      elseif (module_exists('fieldgroup') && ($group_name = fieldgroup_get_group($node->type, $field['field_name'])) && isset($node->content[$group_name]['group'][$field['field_name']])) {
        $wrapper = $node->content[$group_name]['group'][$field['field_name']];
      }

      if ($wrapper) {
        $element = $wrapper['field'];
        // '#single' is not set if the field is hidden or inaccessible.
        if (isset($element['#single'])) {
          if (!empty($element['#single'])) {
            // Single value formatter.
            foreach (element_children($element['items']) as $delta) {
              // '#chilren' is not set if the field is empty.
              $items[$delta]['view'] = isset($element['items'][$delta]['#children']) ? $element['items'][$delta]['#children'] : '';
            }
          }
          elseif (isset($element['items']['#children']))  {
            // Multiple values formatter.
            $items[0]['view'] = $element['items']['#children'];
          }
        }
        else {
          // Hidden or inaccessible field.
          $items[0]['view'] = '';
        }
      }
      break;

    case 'preprocess_node':
      // Add $FIELD_NAME_rendered variables.
      $addition = array();

      // The location of the field's rendered output depends on whether the
      // field is in a fieldgroup or not.
      $wrapper = NULL;
      if (isset($node->content[$field['field_name']])) {
        $wrapper = $node->content[$field['field_name']];
      }
      elseif (module_exists('fieldgroup') && ($group_name = fieldgroup_get_group($node->type, $field['field_name'])) && isset($node->content[$group_name]['group'][$field['field_name']])) {
        $wrapper = $node->content[$group_name]['group'][$field['field_name']];
      }

      if ($wrapper) {
        // '#chilren' is not set if the field is empty.
        $addition[$field['field_name'] .'_rendered'] = isset($wrapper['#children']) ? $wrapper['#children'] : '';
      }

      return $addition;

    case 'prepare translation':
      $addition = array();
      if (isset($node->translation_source->$field['field_name'])) {
        $addition[$field['field_name']] = $node->translation_source->$field['field_name'];
      }
      return $addition;
  }
}

/**
 * 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 $items
 * @return array
 *   returns filtered and adjusted item array
 */
function content_set_empty($field, $items) {
  // Filter out empty values.
  $filtered = array();
  $function = $field['module'] .'_content_is_empty';
  foreach ((array) $items as $delta => $item) {
    if (!$function($item, $field)) {
      $filtered[] = $item;
    }
  }

  // Make sure we store the right number of 'empty' values.
  $empty = array();
  foreach (array_keys($field['columns']) as $column) {
    $empty[$column] = NULL;
  }
  $pad = $field['multiple'] > 1 ? $field['multiple'] : 1;
  $filtered = array_pad($filtered, $pad, $empty);

  return $filtered;
}

/**
 * Helper function to sort items in a field according to
 * user drag-n-drop reordering.
 */
function _content_sort_items($field, $items) {
  if ($field['multiple'] >= 1 && isset($items[0]['_weight'])) {
    usort($items, '_content_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 _content_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 _content_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;
}

/**
 * Handle storage ops for _content_field_invoke_default().
 */
function content_storage($op, $node) {
  // Don't try this before content module's update is run to add
  // the active and module columns.
  if (variable_get('content_schema_version', -1) < 6007) {
    return FALSE;
  }

  $type_name = $node->type;
  $type = content_types($type_name);

  switch ($op) {
    case 'load':
      // OPTIMIZE: load all non multiple fields in a single JOIN query ?
      // warning: 61-join limit in MySQL ?
      $additions = array();
      // For each table used by this content type,
      foreach ($type['tables'] as $table) {
        $schema = drupal_get_schema($table);
        // The per-type table might not have any fields actually stored in it.
        if (!$schema['content fields']) {
          continue;
        }
        $query = 'SELECT * FROM {'. $table .'} WHERE vid = %d';

        // If we're loading a table for a multiple field,
        // we fetch all rows (values) ordered by delta,
        // else we only fetch one row.
        $result = isset($schema['fields']['delta']) ? db_query($query .' ORDER BY delta', $node->vid) : db_query_range($query, $node->vid, 0, 1);

        // For each table row, populate the fields.
        while ($row = db_fetch_array($result)) {
          // For each field stored in the table, add the field item.
          foreach ($schema['content fields'] as $field_name) {
            $item = array();
            $field = content_fields($field_name, $type_name);
            $db_info = content_database_info($field);
            // For each column declared by the field, populate the item.
            foreach ($db_info['columns'] as $column => $attributes) {
              $item[$column] = $row[$attributes['column']];
            }

            // Add the item to the field values for the node.
            if (!isset($additions[$field_name])) {
              $additions[$field_name] = array();
            }
            $additions[$field_name][] = $item;
          }
        }