Drupal username autocomplete callback

autocomplete_callback

/**
 * Ajax callback function for username autocomplete field.
 *
 * @param $name
 *   String, the portion of the autocomplete field already entered.
 */
function _cosign_impersonate_username_autocomplete($name = '') {

  $matches = array();

  if ($name) {

    $query = db_select('users', 'u');
    $return = $query
      ->fields('u', array('name'))
      ->condition('u.name', '%' . db_like($name) . '%', 'LIKE')
      ->range(0, 10)
      ->execute();

    foreach ($return as $row) {

      $matches[$row->name] = check_plain($row->name);

    }

  }

  return drupal_json_output($matches); // Returns the data in JSON format

}

users_by_role

/**
 * Helper to retrieve users and organize them by role to help the impersonater
 * figure out which user to impersonate.
 *
 * @return
 *   HTML output of a table of users by role.
 */
function cosign_impersonate_retrieve_user_table() {

  $output = '';

  $query = db_select('users', 'u');
  $query->join('users_roles', 'ur', 'u.uid = ur.uid');
  $query->join('role', 'r', 'ur.rid = r.rid');
  $return = $query
    ->fields('u', array('name'))
    ->fields('r', array('name'))
    ->orderBy('r.name', 'ASC')
    ->orderBy('u.name', 'ASC')
    ->execute();

  $users_by_role = array();

  foreach ($return as $row) {

    $users_by_role[$row->r_name][] = $row->name;

  }

  foreach ($users_by_role as $role => $users) {

    $output .= '<h4>' . $role . '</h4><ul><li>' . implode('</li><li>', $users) . '</li></ul>';

  }

  return $output;

}