- Patch #756762 by effulgentsia, fago, sun, rfay, pwolanin: AJAX should follow...

- Patch #756762 by effulgentsia, fago, sun, rfay, pwolanin: AJAX should follow same rules for whether to call drupal_rebuild_form() as non-AJAX submissions.

includes/ajax.inc

@@ -239,6 +239,12 @@ function ajax_get_form() {
   // Since some of the submit handlers are run, redirects need to be disabled.
   $form_state['no_redirect'] = TRUE;
 
+  // When a form is rebuilt after AJAX processing, its #build_id and #action
+  // should not change.
+  // @see drupal_rebuild_form()
+  $form_state['rebuild_info']['copy']['#build_id'] = TRUE;
+  $form_state['rebuild_info']['copy']['#action'] = TRUE;
+
   // The form needs to be processed; prepare for that by setting a few internal
   // variables.
   $form_state['input'] = $_POST;
@@ -263,18 +269,15 @@ function ajax_get_form() {
  * enhanced function.
  */
 function ajax_form_callback() {
-  list($form, $form_state, $form_id, $form_build_id) = ajax_get_form();
-
-  // Build, validate and if possible, submit the form.
-  drupal_process_form($form_id, $form, $form_state);
-
-  // This call recreates the form relying solely on the $form_state that
-  // drupal_process_form() set up.
-  $form = drupal_rebuild_form($form_id, $form_state, $form);
-
-  // As part of drupal_process_form(), the element that triggered the form
-  // submission is determined, and in the case of AJAX, it might not be a
-  // button. This lets us route to the appropriate callback.
+  list($form, $form_state) = ajax_get_form();
+  drupal_process_form($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'];
   }

includes/batch.inc

@@ -495,9 +495,12 @@ function _batch_finished() {
     // Use drupal_redirect_form() to handle the redirection logic.
     drupal_redirect_form($_batch['form_state']);
 
-    // If no redirection happened, save the final $form_state value to be
-    // retrieved by drupal_get_form() and redirect to the originating page.
-    $_SESSION['batch_form_state'] = $_batch['form_state'];
+    // If no redirection happened, redirect to the originating page. In case the
+    // form needs to be rebuilt, save the final $form_state for
+    // drupal_build_form().
+    if (!empty($_batch['form_state']['rebuild'])) {
+      $_SESSION['batch_form_state'] = $_batch['form_state'];
+    }
     $function = $_batch['redirect_callback'];
     if (function_exists($function)) {
       $function($_batch['source_url'], array('query' => array('op' => 'finish', 'id' => $_batch['id'])));

modules/file/file.module

@@ -254,7 +254,7 @@ function file_ajax_upload() {
     return array('#type' => 'ajax', '#commands' => $commands, '#header' => FALSE);
   }
 
-  list($form, $form_state, $form_id, $form_build_id) = ajax_get_form();
+  list($form, $form_state) = ajax_get_form();
 
   if (!$form) {
     // Invalid form_build_id.
@@ -271,12 +271,8 @@ function file_ajax_upload() {
   }
   $current_file_count = isset($current_element['#file_upload_delta']) ? $current_element['#file_upload_delta'] : 0;
 
-  // Build, validate and if possible, submit the form.
-  drupal_process_form($form_id, $form, $form_state);
-
-  // This call recreates the form relying solely on the form_state that the
-  // drupal_process_form() set up.
-  $form = drupal_rebuild_form($form_id, $form_state, $form);
+  // Process user input. $form and $form_state are modified in the process.
+  drupal_process_form($form['#form_id'], $form, $form_state);
 
   // Retrieve the element to be rendered.
   foreach ($form_parents as $parent) {

modules/simpletest/tests/form.test

@@ -1011,6 +1011,10 @@ class FormsRebuildTestCase extends DrupalWebTestCase {
     $this->drupalPost(NULL, array(), t('Save'));
     $this->assertText('Title field is required.', t('Non-AJAX submission correctly triggered a validation error.'));
 
+    // Ensure that the form contains two items in the multi-valued field, so we
+    // know we're testing a form that was correctly retrieved from cache.
+    $this->assert(count($this->xpath('//form[contains(@id, "page-node-form")]//div[contains(@class, "form-item-field-ajax-test")]//input[@type="text"]')) == 2, t('Form retained its state from cache.'));
+
     // Ensure that the form's action is correct.
     $forms = $this->xpath('//form[contains(@class, "node-page-form")]');
     $this->assert(count($forms) == 1 && $forms[0]['action'] == url('node/add/page'), t('Re-rendered form contains the correct action value.'));