function ajax_form_callback

Menu callback; handles Ajax requests for the #ajax Form API property.

This rebuilds the form from cache and invokes the defined #ajax['callback'] to return an Ajax command structure for JavaScript. In case no 'callback' has been defined, nothing will happen.

The Form API #ajax property can be set both for buttons and other input elements.

This function is also the canonical example of how to implement #ajax['path']. If processing is required that cannot be accomplished with a callback, re-implement this function and set #ajax['path'] to the enhanced function.

See also

system_menu()

Related topics

File

includes/ajax.inc, line 385

Code

function ajax_form_callback() {
    list($form, $form_state, $form_id, $form_build_id, $commands) = ajax_get_form();
    drupal_process_form($form['#form_id'], $form, $form_state);
    // We need to return the part of the form (or some other content) that needs
    // to be re-rendered so the browser can update the page with changed content.
    // Since this is the generic menu callback used by many Ajax elements, it is
    // up to the #ajax['callback'] function of the element (may or may not be a
    // button) that triggered the Ajax request to determine what needs to be
    // rendered.
    if (!empty($form_state['triggering_element'])) {
        $callback = $form_state['triggering_element']['#ajax']['callback'];
    }
    if (!empty($callback) && is_callable($callback)) {
        $result = $callback($form, $form_state);
        if (!(is_array($result) && isset($result['#type']) && $result['#type'] == 'ajax')) {
            // Turn the response into a #type=ajax array if it isn't one already.
            $result = array(
                '#type' => 'ajax',
                '#commands' => ajax_prepare_response($result),
            );
        }
        $result['#commands'] = array_merge($commands, $result['#commands']);
        return $result;
    }
}