Issue #3018539 by phenaproxima, rodrigoaguilera, alexpott: Media types cannot be created in the UI without JavaScript

(cherry picked from commit 3ba6bc1)

Author: alexpott

modules/media/src/MediaTypeForm.php

@@ -304,6 +304,17 @@ function ($item) {
    */
   protected function actions(array $form, FormStateInterface $form_state) {
     $actions = parent::actions($form, $form_state);
+
+    // If the media source has not been chosen yet, turn the submit button into
+    // a button. This rebuilds the form with the media source's configuration
+    // form visible, instead of saving the media type. This allows users to
+    // create a media type without JavaScript enabled. With JavaScript enabled,
+    // this rebuild occurs during an AJAX request.
+    // @see \Drupal\media\MediaTypeForm::ajaxHandlerData()
+    if (empty($this->getEntity()->get('source'))) {
+      $actions['submit']['#type'] = 'button';
+    }
+
     $actions['submit']['#value'] = $this->t('Save');
     $actions['delete']['#value'] = $this->t('Delete');
     $actions['delete']['#access'] = $this->entity->access('delete');

modules/media/tests/src/Functional/MediaTypeCreationTest.php

@@ -0,0 +1,42 @@
+<?php
+
+namespace Drupal\Tests\media\Functional;
+
+use Drupal\media\Entity\MediaType;
+
+/**
+ * Ensures that media UI works correctly without JavaScript.
+ *
+ * @group media
+ */
+class MediaTypeCreationTest extends MediaFunctionalTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static $modules = [
+    'media_test_source',
+  ];
+
+  /**
+   * Tests the media type creation form with only the mandatory options.
+   */
+  public function testMediaTypeCreationForm() {
+    $machine_name = mb_strtolower($this->randomMachineName());
+
+    $this->drupalGet('/admin/structure/media/add');
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->fieldExists('label')->setValue($this->randomString());
+    $this->assertSession()->fieldExists('id')->setValue($machine_name);
+    $this->assertSession()->selectExists('source')->selectOption('test');
+    $this->assertSession()->buttonExists('Save')->press();
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->fieldValueEquals('Test config value', 'This is default value.');
+    $this->assertSession()->buttonExists('Save')->press();
+    $this->assertSession()->statusCodeEquals(200);
+    $this->assertSession()->addressEquals('admin/structure/media');
+
+    $this->assertInstanceOf(MediaType::class, MediaType::load($machine_name));
+  }
+
+}