function drupal_retrieve_form

Retrieves the structured array that defines a given form.

Parameters

$form_id: The unique string identifying the desired form. If a function with that name exists, it is called to build the form array. Modules that need to generate the same form (or very similar forms) using different $form_ids can implement hook_forms(), which maps different $form_id values to the proper form building function.

...: Any additional arguments needed by the form building function.

Related topics

File

includes/form.inc, line 178

Code

function drupal_retrieve_form($form_id) {
  static $forms;

  // We save two copies of the incoming arguments: one for modules to use
  // when mapping form ids to builder functions, and another to pass to
  // the builder function itself. We shift out the first argument -- the
  // $form_id itself -- from the list to pass into the builder function,
  // since it's already known.
  $args = func_get_args();
  $saved_args = $args;
  array_shift($args);

  // We first check to see if there's a function named after the $form_id.
  // If there is, we simply pass the arguments on to it to get the form.
  if (!function_exists($form_id)) {

    // In cases where many form_ids need to share a central builder function,
    // such as the node editing form, modules can implement hook_forms(). It
    // maps one or more form_ids to the correct builder functions.
    //
    // We cache the results of that hook to save time, but that only works
    // for modules that know all their form_ids in advance. (A module that
    // adds a small 'rate this comment' form to each comment in a list
    // would need a unique form_id for each one, for example.)
    //
    // So, we call the hook if $forms isn't yet populated, OR if it doesn't
    // yet have an entry for the requested form_id.
    if (!isset($forms) || !isset($forms[$form_id])) {
      $forms = module_invoke_all('forms', $saved_args);
    }
    $form_definition = $forms[$form_id];
    if (isset($form_definition['callback arguments'])) {
      $args = array_merge($form_definition['callback arguments'], $args);
    }
    if (isset($form_definition['callback'])) {
      $callback = $form_definition['callback'];
    }
  }

  // If $callback was returned by a hook_forms() implementation, call it.
  // Otherwise, call the function named after the form id.
  $form = call_user_func_array(isset($callback) ? $callback : $form_id, $args);

  // We store the original function arguments, rather than the final $arg
  // value, so that form_alter functions can see what was originally
  // passed to drupal_retrieve_form(). This allows the contents of #parameters
  // to be saved and passed in at a later date to recreate the form.
  $form['#parameters'] = $saved_args;
  return $form;
}