comparison sites/all/modules/references/user_reference/user_reference.module @ 4:ce11bbd8f642

added modules

+<?php
+
+/**
+ * @file
+ * Defines a field type for referencing a user from a node.
+ */
+
+/**
+ * Implements hook_menu().
+ */
+function user_reference_menu() {
+  $items['user_reference/autocomplete/%/%/%'] = array(
+    'page callback' => 'user_reference_autocomplete',
+    'page arguments' => array(2, 3, 4),
+    'access callback' => 'reference_autocomplete_access',
+    'access arguments' => array(2, 3, 4),
+    'type' => MENU_CALLBACK,
+  );
+  return $items;
+}
+
+/**
+ * Implements hook_field_info().
+ */
+function user_reference_field_info() {
+  return array(
+    'user_reference' => array(
+      'label' => t('User reference'),
+      'description' => t('This field stores the ID of a related user as an integer value.'),
+      'settings' => array(
+        'referenceable_roles' => array(),
+        'referenceable_status' => array(),
+        'view' => array(
+          'view_name' => '',
+          'display_name' => '',
+          'args' => array(),
+        ),
+      ),
+      'default_widget' => 'user_reference_autocomplete',
+      'default_formatter' => 'user_reference_default',
+      // Support hook_entity_property_info() from contrib "Entity API".
+      'property_type' => 'user',
+      // Support default token formatter for field tokens.
+      'default_token_formatter' => 'user_reference_plain',
+    ),
+  );
+}
+
+/**
+ * Implements hook_field_settings_form().
+ */
+function user_reference_field_settings_form($field, $instance, $has_data) {
+  $settings = $field['settings'];
+
+  $form = array();
+  $form['referenceable_roles'] = array(
+    '#type' => 'checkboxes',
+    '#title' => t('User roles that can be referenced'),
+    '#default_value' => is_array($settings['referenceable_roles'])
+       ? array_filter($settings['referenceable_roles'])
+       : array(),
+    '#options' => user_roles(TRUE),
+  );
+  $form['referenceable_status'] = array(
+    '#type' => 'checkboxes',
+    '#title' => t('User status that can be referenced'),
+    '#default_value' => is_array($settings['referenceable_status'])
+      ? array_filter($settings['referenceable_status'])
+      : array(1),
+    '#options' => array(1 => t('Active'), 0 => t('Blocked')),
+  );
+
+  if (module_exists('views')) {
+    $view_settings = $settings['view'];
+
+    $description = '<p>' . t('The list of users that can be referenced can provided by a view (Views module) using the "References" display type.') . '</p>';
+
+    // Special note for legacy fields migrated from D6.
+    if (!empty($view_settings['view_name']) && $view_settings['display_name'] == 'default') {
+      $description .= '<p><strong><span class="admin-missing">'. t("Important D6 migration note:") . '</span></strong>';
+      $description .= '<br/>' . t("The field is currently configured to use the 'Master' display of the view %view_name.", array('%view_name' => $view_settings['view_name']));
+      $description .= '<br/>' . t("It is highly recommended that you: <br/>- edit this view and create a new display using the 'References' display type, <br/>- update the field settings to explicitly select the correct view and display.");
+      $description .= '<br/>' . t("The field will work correctly until then, but submitting this form might inadvertently change the field settings.") . '</p>';
+    }
+
+    $form['view'] = array(
+      '#type' => 'fieldset',
+      '#title' => t('Views - Users that can be referenced'),
+      '#collapsible' => TRUE,
+      '#collapsed' => empty($view_settings['view_name']),
+      '#description' => $description,
+    );
+
+    $views_options = references_get_views_options('user');
+    if ($views_options) {
+      // The value of the 'view_and_display' select below will need to be split
+      // into 'view_name' and 'view_display' in the final submitted values, so
+      // we massage the data at validate time on the wrapping element (not
+      // ideal).
+      $form['view']['#element_validate'] = array('_user_reference_view_settings_validate');
+
+      $views_options = array('' => '<' . t('none') . '>') + $views_options;
+      $default = empty($view_settings['view_name']) ? '' : $view_settings['view_name'] . ':' .$view_settings['display_name'];
+      $form['view']['view_and_display'] = array(
+        '#type' => 'select',
+        '#title' => t('View used to select the users'),
+        '#options' => $views_options,
+        '#default_value' => $default,
+        '#description' => '<p>' . t('Choose the view and display that select the nodes that can be referenced.<br />Only views with a display of type "References" are eligible.') . '</p>' .
+          t('Note:<ul><li>This will discard the "Referenceable Roles" and "Referenceable Status" settings above. Use the view\'s "filters" section instead.</li><li>Use the view\'s "fields" section to display additional informations about candidate users on user creation/edition form.</li><li>Use the view\'s "sort criteria" section to determine the order in which candidate users will be displayed.</li></ul>'),
+      );
+
+      $default = implode(', ', $view_settings['args']);
+      $form['view']['args'] = array(
+        '#type' => 'textfield',
+        '#title' => t('View arguments'),
+        '#default_value' => $default,
+        '#required' => FALSE,
+        '#description' => t('Provide a comma separated list of arguments to pass to the view.'),
+      );
+    }
+    else {
+      $form['view']['no_view_help'] = array(
+        '#markup' => '<p>' . t('No eligible view was found.') .'</p>',
+      );
+    }
+  }
+
+  return $form;
+}
+
+/**
+ * Validate callback for the 'view settings' fieldset.
+ *
+ * Puts back the various form values in the expected shape.
+ */
+function _user_reference_view_settings_validate($element, &$form_state, $form) {
+  // Split view name and display name from the 'view_and_display' value.
+  if (!empty($element['view_and_display']['#value'])) {
+    list($view, $display) = explode(':', $element['view_and_display']['#value']);
+  }
+  else {
+    $view = '';
+    $display = '';
+  }
+
+  // Explode the 'args' string into an actual array. Beware, explode() turns an
+  // empty string into an array with one empty string. We'll need an empty array
+  // instead.
+  $args_string = trim($element['args']['#value']);
+  $args = ($args_string === '') ? array() : array_map('trim', explode(',', $args_string));
+
+  $value = array('view_name' => $view, 'display_name' => $display, 'args' => $args);
+  form_set_value($element, $value, $form_state);
+}
+
+/**
+ * Implements hook_field_validate().
+ *
+ * Possible error codes:
+ * - 'invalid_uid': uid is not valid for the field (not a valid user id, or the user is not referenceable).
+ */
+function user_reference_field_validate($entity_type, $entity, $field, $instance, $langcode, $items, &$errors) {
+  // Extract uids to check.
+  $ids = array();
+
+  // First check non-numeric uid's to avoid losing time with them.
+  foreach ($items as $delta => $item) {
+    if (is_array($item) && !empty($item['uid'])) {
+      if (is_numeric($item['uid'])) {
+        $ids[] = $item['uid'];
+      }
+      else {
+        $errors[$field['field_name']][$langcode][$delta][] = array(
+          'error' => 'invalid_uid',
+          'message' => t('%name: invalid input.',
+            array('%name' => $instance['label'])),
+        );
+      }
+    }
+  }
+  // Prevent performance hog if there are no ids to check.
+  if ($ids) {
+    $options = array(
+      'ids' => $ids,
+    );
+    $refs = user_reference_potential_references($field, $options);
+    foreach ($items as $delta => $item) {
+      if (is_array($item)) {
+        if (!empty($item['uid']) && !isset($refs[$item['uid']])) {
+          $errors[$field['field_name']][$langcode][$delta][] = array(
+            'error' => 'invalid_uid',
+            'message' => t("%name: this user can't be referenced.",
+              array('%name' => $instance['label'])),
+          );
+        }
+      }
+    }
+  }
+}
+
+/**
+ * Implements hook_field_prepare_view().
+ */
+function user_reference_field_prepare_view($entity_type, $entities, $field, $instances, $langcode, &$items) {
+  $checked_ids = &drupal_static(__FUNCTION__, array());
+
+  // Set an 'access' property on each item (TRUE if the user exists).
+
+  // Extract ids to check.
+  $ids = array();
+  foreach ($items as $id => $entity_items) {
+    foreach ($entity_items as $delta => $item) {
+      if (is_array($item)) {
+        // Default to 'not accessible'.
+        $items[$id][$delta]['access'] = FALSE;
+        if (!empty($item['uid']) && is_numeric($item['uid'])) {
+          $ids[$item['uid']] = $item['uid'];
+        }
+      }
+    }
+  }
+
+  if ($ids) {
+    // Load information about ids that we haven't already loaded during this
+    // page request.
+    $ids_to_check = array_diff($ids, array_keys($checked_ids));
+    if (!empty($ids_to_check)) {
+      $query = db_select('users', 'u')
+        ->addMetaData('id', 'user_reference_field_prepare_view')
+        ->addMetaData('field', $field)
+        ->fields('u', array('uid'))
+        ->condition('u.uid', $ids_to_check, 'IN');
+      $accessible_ids = $query->execute()->fetchAllAssoc('uid');
+
+      // Populate our static list so that we do not query on those ids again.
+      foreach ($ids_to_check as $id) {
+        $checked_ids[$id] = isset($accessible_ids[$id]);
+      }
+    }
+
+    foreach ($items as $id => $entity_items) {
+      foreach ($entity_items as $delta => $item) {
+        if (is_array($item) && !empty($item['uid']) && !empty($checked_ids[$item['uid']])) {
+          $items[$id][$delta]['access'] = TRUE;
+        }
+      }
+    }
+  }
+}
+
+/**
+ * Implements hook_field_is_empty().
+ */
+function user_reference_field_is_empty($item, $field) {
+  return empty($item['uid']);
+}
+
+/**
+ * Implements hook_field_formatter_info().
+ */
+function user_reference_field_formatter_info() {
+  return array(
+    'user_reference_default' => array(
+      'label' => t('Default'),
+      'description' => t("Display the name of the referenced user as a link to the user's profile page."),
+      'field types' => array('user_reference'),
+    ),
+    'user_reference_plain' => array(
+      'label' => t('Plain text'),
+      'description' => t('Display the name of the referenced user as plain text.'),
+      'field types' => array('user_reference'),
+    ),
+    'user_reference_user' => array(
+      'label'       => t('Rendered user'),
+      'description' => t('Display the referenced user in a specific view mode'),
+      'field types' => array('user_reference'),
+      'settings'    => array('user_reference_view_mode' => 'full'),
+    ),
+    'user_reference_uid' => array(
+      'label' => t('User ID'),
+      'description' => t('Display the referenced user ID'),
+      'field types' => array('user_reference'),
+    ),
+    'user_reference_path' => array(
+      'label' => t('URL as plain text'),
+      'description' => t('Display the URL of the referenced user'),
+      'field types' => array('user_reference'),
+      'settings' => array(
+        'alias' => TRUE,
+        'absolute' => FALSE
+      ),
+    ),
+  );
+}
+
+/**
+ * Implements hook_field_formatter_settings_form().
+ */
+function user_reference_field_formatter_settings_form($field, $instance, $view_mode, $form, &$form_state) {
+  $display = $instance['display'][$view_mode];
+  $settings = $display['settings'];
+
+  $element = array();
+
+  switch ($display['type']) {
+    case 'user_reference_user':
+      $entity_info = entity_get_info('user');
+      $modes = $entity_info['view modes'];
+      $options = array();
+      foreach ($modes as $name => $mode) {
+        $options[$name] = $mode['label'];
+      }
+      $element['user_reference_view_mode'] = array(
+        '#title'   => t('View mode'),
+        '#type'    => 'select',
+        '#options' => $options,
+        '#default_value' => $settings['user_reference_view_mode'],
+        // Never empty, so no #empty_option
+      );
+      break;
+
+    case 'user_reference_path':
+      $element['alias'] = array(
+        '#type' => 'checkbox',
+        '#title' => t('Display the aliased path (if exists) instead of the system path'),
+        '#default_value' => $settings['alias'],
+      );
+      $element['absolute'] = array(
+        '#type' => 'checkbox',
+        '#title' => t('Display an absolute URL'),
+        '#default_value' => $settings['absolute'],
+      );
+      break;
+  }
+
+  return $element;
+}
+
+/**
+ * Implements hook_field_formatter_settings_summary().
+ */
+function user_reference_field_formatter_settings_summary($field, $instance, $view_mode) {
+  $display = $instance['display'][$view_mode];
+  $settings = $display['settings'];
+  $summary = array();
+
+  switch ($display['type']) {
+    case 'user_reference_user':
+      $entity_info = entity_get_info('user');
+      $modes = $entity_info['view modes'];
+      $mode = $modes[$settings['user_reference_view_mode']]['label'];
+      $summary[] = t('View mode: %mode', array('%mode' => $mode));
+      break;
+
+    case 'user_reference_path':
+      $summary[] = t('Aliased path: %yes_no', array('%yes_no' => $settings['alias'] ? t('Yes') : t('No')));
+      $summary[] = t('Absolute URL: %yes_no', array('%yes_no' => $settings['absolute'] ? t('Yes') : t('No')));
+      break;
+  }
+
+  return implode('<br />', $summary);
+}
+
+
+/**
+ * Implements hook_field_formatter_prepare_view().
+ *
+ * Preload all user referenced by items using 'full entity' formatters.
+ */
+function user_reference_field_formatter_prepare_view($entity_type, $entities, $field, $instances, $langcode, &$items, $displays) {
+  // Load the referenced users, except for the 'user_reference_uid' which does
+  // not need full objects.
+
+  // Collect ids to load.
+  $ids = array();
+  foreach ($displays as $id => $display) {
+    if ($display['type'] != 'user_reference_uid') {
+      foreach ($items[$id] as $delta => $item) {
+        if ($item['access']) {
+          $ids[$item['uid']] = $item['uid'];
+        }
+      }
+    }
+  }
+  $entities = user_load_multiple($ids);
+
+  // Add the loaded user objects to the items.
+  foreach ($displays as $id => $display) {
+    if ($display['type'] != 'user_reference_uid') {
+      foreach ($items[$id] as $delta => $item) {
+        if ($item['access']) {
+          $items[$id][$delta]['user'] = $entities[$item['uid']];
+        }
+      }
+    }
+  }
+}
+
+/**
+ * Implements hook_field_formatter_view().
+ */
+function user_reference_field_formatter_view($entity_type, $entity, $field, $instance, $langcode, $items, $display) {
+  $settings = $display['settings'];
+  $result = array();
+
+  // @todo Optimisation: use hook_field_formatter_prepare_view() to load
+  // user names or full user entities in 'multiple' mode.
+
+  // Collect the list of user ids.
+  $uids = array();
+  foreach ($items as $delta => $item) {
+    $uids[$item['uid']] = $item['uid'];
+  }
+
+  switch ($display['type']) {
+    case 'user_reference_default':
+    case 'user_reference_plain':
+      foreach ($items as $delta => $item) {
+        if ($item['access']) {
+          $user = $item['user'];
+          $label = entity_label('user', $user);
+          if ($display['type'] == 'user_reference_default') {
+            $uri = entity_uri('user', $user);
+            $result[$delta] = array(
+              '#type' => 'link',
+              '#title' => $label,
+              '#href' => $uri['path'],
+              '#options' => $uri['options'],
+            );
+          }
+          else {
+            $result[$delta] = array(
+              '#markup' => check_plain($label),
+            );
+          }
+        }
+      }
+      break;
+
+    case 'user_reference_user':
+      $view_mode = $display['settings']['user_reference_view_mode'];
+      // To prevent infinite recursion caused by reference cycles, we store
+      // diplayed accounts in a recursion queue.
+      $recursion_queue = &drupal_static(__FUNCTION__, array());
+
+      // If no 'referencing entity' is set, we are starting a new 'reference
+      // thread' and need to reset the queue.
+      // @todo Bug: $entity->referencing_entity on accounts referenced in a different
+      // thread on the page. E.g: 1 references 1+2 / 2 references 1+2 / visit homepage.
+      // We'd need a more accurate way...
+      if (!isset($entity->referencing_entity)) {
+        $recursion_queue = array();
+      }
+
+      // The recursion queue only needs to track nodes.
+      if ($entity_type == 'user') {
+        list($id) = entity_extract_ids($entity_type, $entity);
+        $recursion_queue[$id] = $id;
+      }
+
+      // Check the recursion queue to determine which accounts should be fully
+      // displayed, and which accounts will only be displayed as a username.
+      $users_display = array();
+      foreach ($items as $delta => $item) {
+        if ($item['access'] && !isset($recursion_queue[$item['uid']])) {
+          $users_display[$item['uid']] = $item['user'];
+        }
+      }
+
+      // Load and build the fully displayed nodes.
+      if ($users_display) {
+        $users_built = array('users' => array('#sorted' => TRUE));
+        foreach ($users_display as $uid => $account) {
+          $users_display[$uid]->referencing_entity = $entity;
+          $users_display[$uid]->referencing_field = $field['field_name'];
+          $users_built['users'][$account->uid] = user_view($account, $settings['user_reference_view_mode']);
+        }
+      }
+
+      // Assemble the render array.
+      foreach ($items as $delta => $item) {
+        if ($item['access']) {
+          if (isset($users_display[$item['uid']])) {
+            $result[$delta] = $users_built['users'][$item['uid']];
+          }
+          else {
+            $account = $item['user'];
+            $label = entity_label('user', $user);
+            $uri = entity_uri('user', $account);
+            $result[$delta] = array(
+              '#type' => 'link',
+              '#title' => $label,
+              '#href' => $uri['path'],
+              '#options' => $uri['options'],
+            );
+            if (!$account->status) {
+              $result[$delta]['#prefix'] = '<span class="user-unpublished">';
+              $result[$delta]['#suffix'] = '</span>';
+            }
+          }
+        }
+      }
+      break;
+
+    case 'user_reference_uid':
+      foreach ($items as $delta => $item) {
+        if ($item['access']) {
+          $result[$delta] = array(
+            '#markup' => $item['uid'],
+          );
+        }
+      }
+      break;
+
+    case 'user_reference_path':
+      foreach ($items as $delta => $item) {
+        if ($item['access']) {
+          $uri = entity_uri('user', $item['user']);
+          $options = array(
+            'absolute' => $settings['absolute'],
+            'alias' => !$settings['alias'],
+          );
+
+          $options += $uri['options'];
+          $result[$delta] = array(
+            '#markup' => url($uri['path'], $options),
+          );
+        }
+      }
+      break;
+  }
+
+  return $result;
+}
+
+/**
+ * Helper function for widgets and formatters.
+ *
+ * Store user names collected in the curent request.
+ */
+function _user_reference_get_user_names($uids, $known_titles = array()) {
+  $titles = &drupal_static(__FUNCTION__, array());
+
+  // Save titles we receive.
+  $titles += $known_titles;
+
+  // Collect nids to retrieve from database.
+  $uids_query = array();
+  foreach ($uids as $uid) {
+    if (!isset($titles[$uid])) {
+      $uids_query[] = $uid;
+    }
+  }
+  if ($uids_query) {
+    $query = db_select('users', 'u')
+      ->fields('u', array('uid', 'name'))
+      ->condition('u.uid', $uids);
+    $titles += $query->execute()->fetchAllKeyed();
+  }
+
+  // Build the results array.
+  $return = array();
+  foreach ($uids as $uid) {
+    $return[$uid] = isset($titles[$uid]) ? $titles[$uid] : '';
+  }
+
+  return $return;
+}
+
+/**
+ * Implements hook_field_widget_info().
+ */
+function user_reference_field_widget_info() {
+  return array(
+    'user_reference_autocomplete' => array(
+      'label' => t('Autocomplete text field'),
+      'description' => t('Display the list of referenceable users as a textfield with autocomplete behaviour.'),
+      'field types' => array('user_reference'),
+      'settings' => array(
+        'autocomplete_match' => 'contains',
+        'size' => 60,
+        'autocomplete_path' => 'user_reference/autocomplete',
+      ),
+    ),
+  );
+}
+
+/**
+ * Implements hook_field_widget_info_alter().
+ */
+function user_reference_field_widget_info_alter(&$info) {
+  $info['options_select']['field types'][] = 'user_reference';
+  $info['options_buttons']['field types'][] = 'user_reference';
+}
+
+/**
+ * Implements hook_field_widget_settings_form().
+ */
+function user_reference_field_widget_settings_form($field, $instance) {
+  $widget   = $instance['widget'];
+  $defaults = field_info_widget_settings($widget['type']);
+  $settings = array_merge($defaults, $widget['settings']);
+
+  $form = array();
+  if ($widget['type'] == 'user_reference_autocomplete') {
+    $form['autocomplete_match'] = array(
+      '#type'             => 'select',
+      '#title'            => t('Autocomplete matching'),
+      '#default_value'    => $settings['autocomplete_match'],
+      '#options'          => array(
+        'starts_with'     => t('Starts with'),
+        'contains'        => t('Contains'),
+      ),
+      '#description'      => t('Select the method used to collect autocomplete suggestions. Note that <em>Contains</em> can cause performance issues on sites with thousands of users.'),
+    );
+    $form['size'] = array(
+      '#type'             => 'textfield',
+      '#title'            => t('Size of textfield'),
+      '#default_value'    => $settings['size'],
+      '#element_validate' => array('_element_validate_integer_positive'),
+      '#required'         => TRUE,
+    );
+  }
+ return $form;
+}
+
+/**
+ * Implements hook_field_widget_form().
+ */
+function user_reference_field_widget_form(&$form, &$form_state, $field, $instance, $langcode, $items, $delta, $element) {
+  switch ($instance['widget']['type']) {
+    case 'user_reference_autocomplete':
+      $element += array(
+        '#type' => 'textfield',
+        '#default_value' => isset($items[$delta]['uid']) ? $items[$delta]['uid'] : NULL,
+        '#autocomplete_path' => $instance['widget']['settings']['autocomplete_path'] . '/' . $instance['entity_type'] . '/' . $instance['bundle'] . '/' . $field['field_name'],
+        '#size' => $instance['widget']['settings']['size'],
+        '#element_validate' => array('user_reference_autocomplete_validate'),
+        '#value_callback' => 'user_reference_autocomplete_value',
+      );
+      break;
+  }
+  return array('uid' => $element);
+}
+
+/**
+ * Value callback for a user_reference autocomplete element.
+ *
+ * Substitute in the user name for the uid.
+ */
+function user_reference_autocomplete_value($element, $input = FALSE, $form_state) {
+  if ($input === FALSE) {
+    // We're building the displayed 'default value': expand the raw uid into
+    // "user name [uid:n]".
+    $uid = $element['#default_value'];
+    if (!empty($uid)) {
+      $q = db_select('users', 'u');
+      $q->addField('u', 'name');
+
+      $q->condition('u.uid', $uid)
+        ->range(0, 1);
+      $result = $q->execute();
+      // @todo If no result (user doesn't exist).
+      $value = $result->fetchField();
+      $value .= ' [uid:' . $uid . ']';
+      return $value;
+    }
+  }
+}
+
+/**
+ * Validation callback for a user_reference autocomplete element.
+ */
+function user_reference_autocomplete_validate($element, &$form_state, $form) {
+  $field = field_widget_field($element, $form_state);
+  $instance = field_widget_instance($element, $form_state);
+
+  $value = $element['#value'];
+  $uid = NULL;
+
+  if (!empty($value)) {
+    // Check whether we have an explicit "[uid:n]" input.
+    preg_match('/^(?:\s*|(.*) )?\[\s*uid\s*:\s*(\d+)\s*\]$/', $value, $matches);
+    if (!empty($matches)) {
+      // Explicit uid. Check that the 'name' part matches the actual name for
+      // the uid.
+      list(, $name, $uid) = $matches;
+      if (!empty($name)) {
+        $names = _user_reference_get_user_names(array($uid));
+        if ($name != $names[$uid]) {
+          form_error($element, t('%name: name mismatch. Please check your selection.', array('%name' => $instance['label'])));
+        }
+      }
+    }
+    else {
+      // No explicit uid (the submitted value was not populated by autocomplete
+      // selection). Get the uid of a referencable user from the entered name.
+      $options = array(
+        'string' => $value,
+        'match' => 'equals',
+        'limit' => 1,
+      );
+      $references = user_reference_potential_references($field, $options);
+      if ($references) {
+        // @todo The best thing would be to present the user with an
+        // additional form, allowing the user to choose between valid
+        // candidates with the same name. ATM, we pick the first
+        // matching candidate...
+        $uid = key($references);
+      }
+      else {
+        form_error($element, t('%name: found no valid user with that name.', array('%name' => $instance['label'])));
+      }
+    }
+  }
+
+  // Set the element's value as the user id that was extracted from the entered
+  // input.
+  form_set_value($element, $uid, $form_state);
+}
+
+/**
+ * Implements hook_field_widget_error().
+ */
+function user_reference_field_widget_error($element, $error, $form, &$form_state) {
+  form_error($element['uid'], $error['message']);
+}
+
+/**
+ * Builds a list of referenceable users suitable for the '#option' FAPI property.
+ *
+ * Warning: the function does NOT take care of encoding or escaping the user
+ * names. Proper massaging needs to be performed by the caller, according to
+ * the destination FAPI '#type' (radios / checkboxes / select).
+ *
+ * @param $field
+ *   The field definition.
+ *
+ * @return
+ *   An array of referenceable user names, keyed by user id.
+ */
+function _user_reference_options($field, $flat = TRUE) {
+  $references = user_reference_potential_references($field);
+
+  $options = array();
+  foreach ($references as $key => $value) {
+    // The label, displayed in selects and checkboxes/radios, should have HTML
+    // entities unencoded. The widgets (core's options.module) take care of
+    // applying the relevant filters (strip_tags() or filter_xss()).
+    $label = html_entity_decode($value['rendered'], ENT_QUOTES);
+    if (empty($value['group']) || $flat) {
+      $options[$key] = $label;
+    }
+    else {
+      // The group name, displayed in selects, cannot contain tags, and should
+      // have HTML entities unencoded.
+      $group = html_entity_decode(strip_tags($value['group']), ENT_QUOTES);
+      $options[$group][$key] = $label;
+    }
+  }
+
+  return $options;
+}
+
+/**
+ * Retrieves an array of candidate referenceable users.
+ *
+ * This info is used in various places (aloowed values, autocomplete results,
+ * input validation...). Some of them only need the uids, others nid + names,
+ * others yet uid + names + rendered row (for display in widgets).
+ * The array we return contains all the potentially needed information, and lets
+ * consumers use the parts they actually need.
+ *
+ * @param $field
+ *   The field definition.
+ * @param $options
+ *   An array of options to limit the scope of the returned list. The following
+ *   key/value pairs are accepted:
+ *   - string: string to filter titles on (used by autocomplete).
+ *   - match: operator to match the above string against, can be any of:
+ *     'contains', 'equals', 'starts_with'. Defaults to 'contains'.
+ *   - ids: array of specific node ids to lookup.
+ *   - limit: maximum size of the the result set. Defaults to 0 (no limit).
+ *
+ * @return
+ *   An array of valid users in the form:
+ *   array(
+ *     uid => array(
+ *       'title' => The user name,
+ *       'rendered' => The text to display in widgets (can be HTML)
+ *     ),
+ *     ...
+ *   )
+ */
+function user_reference_potential_references($field, $options = array()) {
+  // Fill in default options.
+  $options += array(
+    'string' => '',
+    'match' => 'contains',
+    'ids' => array(),
+    'limit' => 0,
+  );
+
+  $results = &drupal_static(__FUNCTION__, array());
+
+  // Create unique id for static cache.
+  $cid = $field['field_name'] . ':' . $options['match'] . ':'
+    . ($options['string'] !== '' ? $options['string'] : implode('-', $options['ids']))
+    . ':' . $options['limit'];
+  if (!isset($results[$cid])) {
+    $references = FALSE;
+    if (module_exists('views') && !empty($field['settings']['view']['view_name'])) {
+      $references = _user_reference_potential_references_views($field, $options);
+    }
+
+    if ($references === FALSE) {
+      $references = _user_reference_potential_references_standard($field, $options);
+    }
+
+    // Store the results.
+    $results[$cid] = !empty($references) ? $references : array();
+  }
+
+  return $results[$cid];
+}
+
+/**
+ * Helper function for user_reference_potential_references().
+ *
+ * Case of Views-defined referenceable users.
+ */
+function _user_reference_potential_references_views($field, $options) {
+  $settings = $field['settings']['view'];
+  $options['title_field'] = 'name';
+  return references_potential_references_view('user', $settings['view_name'], $settings['display_name'], $settings['args'], $options);
+}
+
+/**
+ * Helper function for user_reference_potential_references().
+ *
+ * List of referenceable users defined by user role and status.
+ */
+function _user_reference_potential_references_standard($field, $options) {
+  // Avoid useless work.
+  $filter_roles = array_filter($field['settings']['referenceable_roles']);
+  $filter_status = array_filter($field['settings']['referenceable_status']);
+  if (!count($filter_status) && !count($filter_roles)) {
+    return array();
+  }
+
+  $query = db_select('users', 'u')
+    // Select the whole record, so that format_username() has enough
+    // information.
+    ->fields('u')
+    ->addMetaData('id', ' _user_reference_potential_references_standard')
+    ->addMetaData('field', $field)
+    ->addMetaData('options', $options);
+
+  // Enable this filter only if any statuses checked (and not both).
+  if (count($filter_status) == 1) {
+    $query->condition('u.status', array_keys($filter_status), 'IN');
+  }
+
+  // Skip filter when "authenticated user" choosen.
+  if ($filter_roles && !isset($filter_roles[DRUPAL_AUTHENTICATED_RID])) {
+    $query->join('users_roles', 'r', 'u.uid = r.uid');
+    $query->condition('r.rid', array_keys($filter_roles), 'IN');
+  }
+
+  if ($options['string'] !== '') {
+    switch ($options['match']) {
+      case 'contains':
+        $query->condition('u.name', '%' . $options['string'] . '%', 'LIKE');
+        break;
+
+      case 'starts_with':
+        $query->condition('u.name', $options['string'] . '%', 'LIKE');
+        break;
+
+      case 'equals':
+      default: // no match type or incorrect match type: use "="
+        $query->condition('u.name', $options['string'], '=');
+        break;
+    }
+  }
+
+  if ($options['ids']) {
+    $query->condition('u.uid', $options['ids'], 'IN');
+  }
+
+  // Explicitly exclude the anonymous user.
+  $query->condition('u.uid', 0, '<>');
+
+  if ($options['limit']) {
+    $query->range(0, $options['limit']);
+  }
+  $query->orderBy('u.name');
+
+  $result = $query->execute()->fetchAll();
+  $references = array();
+  foreach ($result as $account) {
+    $references[$account->uid] = array(
+      'title'    => $account->name,
+      'rendered' => check_plain(format_username($account)),
+    );
+  }
+  return $references;
+}
+
+/**
+ * Menu callback; Retrieve a pipe delimited string of autocomplete suggestions for existing users
+ */
+function user_reference_autocomplete($entity_type, $bundle, $field_name, $string = '') {
+  $field = field_info_field($field_name);
+  $instance = field_info_instance($entity_type, $field_name, $bundle);
+
+  $options = array(
+    'string' => $string,
+    'match' => $instance['widget']['settings']['autocomplete_match'],
+    'limit' => 10,
+  );
+  $references = user_reference_potential_references($field, $options);
+
+  $matches = array();
+  foreach ($references as $id => $row) {
+    // Markup is fine in autocompletion results (might happen when rendered
+    // through Views) but we want to remove hyperlinks.
+    $suggestion = preg_replace('/<a href="([^<]*)">([^<]*)<\/a>/', '$2', $row['rendered']);
+    // Remove link tags Add a class wrapper for a few required CSS overrides.
+    $matches[$row['title'] . " [uid:$id]"] = '<div class="reference-autocomplete">' . $suggestion . '</div>';
+  }
+  drupal_json_output($matches);
+}
+
+/**
+ * Implements hook_options_list().
+ */
+function user_reference_options_list($field) {
+  return _user_reference_options($field, FALSE);
+}
+
+/**
+ * Implementation of hook_user_load().
+ */
+/*function user_reference_user_load($accounts) {
+
+  // Only add links if we are on the user 'view' page.
+  if (arg(0) != 'user' || arg(2)) {
+    return;
+  }
+
+  foreach ($accounts as $uid => $account) {
+
+    // find CCK user_reference field tables
+    // search through them for matching user ids and load those nodes
+    $additions = array();
+    $fields = field_info_instances('user');
+
+    // TODO : replace with field_attach_query() + synchronize with latest D6 code.
+
+    // Find the table and columns to search through, if the same
+    // table comes up in more than one field type, we only need
+    // to search it once.
+    $search_tables = array();
+    $search_links = array();
+    foreach ($fields as $field) {
+      if ($field['type'] == 'user_reference' && !empty($field['widget']['reverse_link'])) {
+        $db_info = content_database_info($field);
+        $search_tables[$db_info['table']] = $db_info['columns']['uid']['column'];
+        $search_links[$db_info['table']] = $field['widget']['reverse_link'];
+      }
+    }
+    foreach ($search_tables as $table => $column) {
+      $ids = db_query(db_rewrite_sql("SELECT DISTINCT(n.nid) FROM {node} n LEFT JOIN {". $table ."} f ON n.vid = f.vid WHERE f.". $column ."=". $account->uid. " AND n.status = 1"));
+      while ($data = db_fetch_object($ids)) {
+        // TODO, do we really want a complete node_load() here? We only need the title to create a link.
+        $node = node_load($data->nid);
+        $node->reverse_link = $search_links[$table];
+        $additions[$node->type][] = $node;
+      }
+    }
+    $accounts[$uid]->user_reference = $additions;
+  }
+  return;
+}*/
+
+/**
+ * Implementation of hook_user_view().
+ */
+/*function user_reference_user_view($account, $view_mode, $langcode) {
+  if (!empty($account->user_reference)) {
+    $node_types = content_types();
+    $additions = array();
+    $values = array();
+    foreach ($account->user_reference as $node_type => $nodes) {
+      foreach ($nodes as $node) {
+        if ($node->reverse_link) {
+          $values[$node_type][] = l($node->title, 'node/' . $node->nid);
+        }
+      }
+      if (isset($values[$node_type])) {
+        $additions[] = array(
+          '#type' => 'user_profile_item',
+          '#title' => check_plain($node_types[$node_type]['name']),
+          '#value' => theme('item_list', $values[$node_type]),
+        );
+      }
+    }
+    if ($additions) {
+      $account->content['user_reference'] = $additions + array(
+        '#type' => 'user_profile_category',
+        '#attributes' => array('class' => array('user-member')),
+        '#title' => t('Related content'),
+        '#weight' => 10,
+      );
+    }
+  }
+}*/
+
+/**
+ * Implements hook_content_migrate_field_alter().
+ *
+ * Use this to tweak the conversion of field settings
+ * from the D6 style to the D7 style for specific
+ * situations not handled by basic conversion,
+ * as when field types or settings are changed.
+ *
+ * $field_value['widget_type'] is available to
+ * see what widget type was originally used.
+ */
+function user_reference_content_migrate_field_alter(&$field_value, $instance_value) {
+  switch ($field_value['module']) {
+    case 'userreference':
+      $field_value['module'] = 'user_reference';
+      $field_value['type'] = 'user_reference';
+
+      // Translate 'view' settings.
+      $view_name = isset($field_value['settings']['advanced_view']) ? $field_value['settings']['advanced_view'] : '';
+      $view_args = isset($field_value['settings']['advanced_view_args']) ? $field_value['settings']['advanced_view_args'] : '';
+      $view_args = array_map('trim', explode(',', $view_args));
+      $field_value['settings']['view'] = array(
+        'view_name' => $view_name,
+        'display_name' => 'default',
+        'args' => $view_args,
+      );
+      if ($view_name) {
+        $field_value['messages'][] = t("The field uses the view @view_name to determine referenceable users. You will need to manually edit the view and add a display of type 'References'.", array('@view_name' => $view_name));
+      }
+      unset($field_value['settings']['advanced_view']);
+      unset($field_value['settings']['advanced_view_args']);
+      break;
+  }
+}
+
+/**
+ * Implements hook_content_migrate_instance_alter().
+ *
+ * Use this to tweak the conversion of instance or widget settings
+ * from the D6 style to the D7 style for specific
+ * situations not handled by basic conversion, as when
+ * formatter or widget names or settings are changed.
+ */
+function user_reference_content_migrate_instance_alter(&$instance_value, $field_value) {
+  // The module name for the instance was corrected
+  // by the change in user_reference_content_migrate_field_alter().
+  switch ($field_value['type']) {
+    case 'userreference':
+      // The formatter names changed, all are prefixed
+      // with 'user_reference_'.
+      foreach ($instance_value['display'] as $context => $settings) {
+        $instance_value['display'][$context]['type'] = 'user_reference_' . $settings['type'];
+      }
+      // Massage the widget.
+      switch ($instance_value['widget']['type']) {
+        case 'userreference_autocomplete':
+          $instance_value['widget']['type'] = 'user_reference_autocomplete';
+          $instance_value['widget']['module'] = 'user_reference';
+          break;
+        case 'userreference_select':
+          $instance_value['widget']['type'] = 'options_select';
+          $instance_value['widget']['module'] = 'options';
+          break;
+        case 'userreference_buttons':
+          $instance_value['widget']['type'] = 'options_buttons';
+          $instance_value['widget']['module'] = 'options';
+      }
+      break;
+  }
+}
+
+/**
+ * Implements hook_field_views_data().
+ *
+ * In addition to the default field information we add the relationship for
+ * views to connect back to the users table.
+ */
+function user_reference_field_views_data($field) {
+  // No module_load_include(): this hook is invoked from
+  // views/modules/field.views.inc, which is where that function is defined.
+  $data = field_views_field_default_views_data($field);
+
+  $storage = $field['storage']['details']['sql'];
+
+  foreach ($storage as $age => $table_data) {
+    $table = key($table_data);
+    $columns = current($table_data);
+    $id_column = $columns['uid'];
+    if (isset($data[$table])) {
+      // Filter: swap the handler to the 'in' operator. The callback receives
+      // the field name instead of the whole $field structure to keep views
+      // data to a reasonable size.
+      $data[$table][$id_column]['filter']['handler'] = 'views_handler_filter_in_operator';
+      $data[$table][$id_column]['filter']['options callback'] = 'user_reference_views_filter_options';
+      $data[$table][$id_column]['filter']['options arguments'] = array($field['field_name']);
+
+      // Argument: display users.name in argument titles (handled in our custom
+      // handler) and summary lists (handled by the base views_handler_argument
+      // handler).
+      // Both mechanisms rely on the 'name table' and 'name field' information
+      // below, by joining to a separate copy of the base table from the field
+      // data table.
+      $data[$table][$id_column]['argument']['handler'] = 'references_handler_argument';
+      $data[$table][$id_column]['argument']['name table'] = $table . '_reference';
+      $data[$table][$id_column]['argument']['name field'] = 'name';
+      $data[$table . '_reference']['table']['join'][$table] = array(
+        'left_field' => $id_column,
+        'table' => 'users',
+        'field' => 'uid',
+      );
+
+      // Relationship.
+      $data[$table][$id_column]['relationship'] = array(
+        'handler' => 'references_handler_relationship',
+        'base' => 'users',
+        'base field' => 'uid',
+        'field' => $id_column,
+        'label' => $field['field_name'],
+        'field_name' => $field['field_name'],
+      );
+    }
+  }
+
+  return $data;
+}
+
+/**
+ * Implements hook_field_views_data_views_data_alter().
+ */
+function user_reference_field_views_data_views_data_alter(&$data, $field) {
+  foreach ($field['bundles'] as $entity_type => $bundles) {
+    $entity_info = entity_get_info($entity_type);
+    $pseudo_field_name = 'reverse_' . $field['field_name'] . '_' . $entity_type;
+
+    list($label, $all_labels) = field_views_field_label($field['field_name']);
+    $entity = $entity_info['label'];
+    if ($entity == t('Node')) {
+      $entity = t('Content');
+    }
+
+    // Only specify target entity type if the field is used in more than one.
+    if (count($field['bundles']) > 1) {
+      $title = t('@field (@field_name) - reverse (to @entity)', array('@entity' => $entity, '@field' => $label, '@field_name' => $field['field_name']));
+    }
+    else {
+      $title = t('@field (@field_name) - reverse', array('@entity' => $entity, '@field' => $label, '@field_name' => $field['field_name']));
+    }
+    $data['users'][$pseudo_field_name]['relationship'] = array(
+      'title' => $title,
+      'help' => t('Relate each @entity referencing the user through @field.', array('@entity' => $entity, '@field' => $label)),
+      'handler' => 'views_handler_relationship_entity_reverse',
+      'field_name' => $field['field_name'],
+      'field table' => _field_sql_storage_tablename($field),
+      'field field' => $field['field_name'] . '_uid',
+      'base' => $entity_info['base table'],
+      'base field' => $entity_info['entity keys']['id'],
+      'label' => t('!field_name', array('!field_name' => $field['field_name'])),
+    );
+  }
+}
+
+/**
+ * 'options callback' for the views_handler_filter_in_operator filter.
+ *
+ * @param $field_name
+ *   The field name.
+ *
+ * @return
+ *   The array of allowed options for the filter.
+ */
+function user_reference_views_filter_options($field_name) {
+  $options = array();
+
+  if ($field = field_info_field($field_name)) {
+    $options = _user_reference_options($field, TRUE);
+
+    // The options are displayed in checkboxes within the filter admin form, and
+    // in a select within an exposed filter. Checkboxes accept HTML, other
+    // entities should be encoded; selects require the exact opposite: no HTML,
+    // no encoding. We go for a middle ground: strip tags, leave entities
+    // unencoded.
+    foreach ($options as $key => $value) {
+      $options[$key] = strip_tags($value);
+    }
+  }
+
+  return $options;
+}