function drupal_get_form

Retrieves a form from a constructor function, or from the cache if the form was built in a previous page-load. The form is then passed on for processing, after and rendered for display if necessary.

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 constructor function. Examples may be found in node_forms(), search_forms(), and user_forms().

...: Any additional arguments are passed on to the functions called by drupal_get_form(), including the unique form constructor function. For example, the node_edit form requires that a node object be passed in here when it is called. These are available to implementations of hook_form_alter() and hook_form_FORM_ID_alter() as the array $form['#parameters'].

Return value

The rendered form.

Related topics

File

includes/form.inc, line 70

Code

function drupal_get_form($form_id) {
  $form_state = array(
    'storage' => NULL,
    'submitted' => FALSE,
  );
  $args = func_get_args();
  $cacheable = FALSE;
  if (isset($_SESSION['batch_form_state'])) {

    // We've been redirected here after a batch processing : the form has
    // already been processed, so we grab the post-process $form_state value
    // and move on to form display. See _batch_finished() function.
    $form_state = $_SESSION['batch_form_state'];
    unset($_SESSION['batch_form_state']);
  }
  else {

    // If the incoming $_POST contains a form_build_id, we'll check the
    // cache for a copy of the form in question. If it's there, we don't
    // have to rebuild the form to proceed. In addition, if there is stored
    // form_state data from a previous step, we'll retrieve it so it can
    // be passed on to the form processing code.
    if (isset($_POST['form_id']) && $_POST['form_id'] == $form_id && !empty($_POST['form_build_id'])) {
      $form = form_get_cache($_POST['form_build_id'], $form_state);
    }

    // If the previous bit of code didn't result in a populated $form
    // object, we're hitting the form for the first time and we need
    // to build it from scratch.
    if (!isset($form)) {
      $form_state['post'] = $_POST;

      // Use a copy of the function's arguments for manipulation
      $args_temp = $args;
      $args_temp[0] =& $form_state;
      array_unshift($args_temp, $form_id);
      $form = call_user_func_array('drupal_retrieve_form', $args_temp);
      $form_build_id = 'form-' . drupal_random_key();
      $form['#build_id'] = $form_build_id;
      drupal_prepare_form($form_id, $form, $form_state);

      // Store a copy of the unprocessed form for caching and indicate that it
      // is cacheable if #cache will be set.
      $original_form = $form;
      $cacheable = TRUE;
      unset($form_state['post']);
    }
    $form['#post'] = $_POST;

    // Now that we know we have a form, we'll process it (validating,
    // submitting, and handling the results returned by its submission
    // handlers. Submit handlers accumulate data in the form_state by
    // altering the $form_state variable, which is passed into them by
    // reference.
    drupal_process_form($form_id, $form, $form_state);
    if ($cacheable && !empty($form['#cache'])) {

      // Caching is done past drupal_process_form so #process callbacks can
      // set #cache.
      form_set_cache($form_build_id, $original_form, $form_state);
    }
  }

  // Most simple, single-step forms will be finished by this point --
  // drupal_process_form() usually redirects to another page (or to
  // a 'fresh' copy of the form) once processing is complete. If one
  // of the form's handlers has set $form_state['redirect'] to FALSE,
  // the form will simply be re-rendered with the values still in its
  // fields.
  //
  // If $form_state['storage'] or $form_state['rebuild'] has been set
  // and input has been processed, we know that we're in a complex
  // multi-part process of some sort and the form's workflow is NOT
  // complete. We need to construct a fresh copy of the form, passing
  // in the latest $form_state in addition to any other variables passed
  // into drupal_get_form().
  if ((!empty($form_state['storage']) || !empty($form_state['rebuild'])) && !empty($form_state['process_input']) && !form_get_errors()) {
    $form = drupal_rebuild_form($form_id, $form_state, $args);
  }

  // If we haven't redirected to a new location by now, we want to
  // render whatever form array is currently in hand.
  return drupal_render_form($form_id, $form);
}