I want to create my own version of the add/edit form for an entity defined in contrib module (drupal_commerce). I assumed i'd be able to adapt the example here http://www.foreach.be/blog/how-manipulate-forms-drupal-8 to alter route for entity forms. However i am getting the following when i try to load edit

Fatal error: Call to a member function getEntityTypeId() on a non-object in C:\xampp\htdocs\tocyn\core\lib\Drupal\Core\Entity\EntityForm.php on line 82

My route subscriber looks like:

    if ($route = $collection->get('entity.commerce_product.edit_form') ) {
        $defs = $route->getDefaults();
        $route->setDefault('_form', '\Drupal\mymod\Form\EventForm');

And my new form:

class EventForm extends Drupal\commerce_product\Form\ProductForm
   public function buildForm(array $form, FormStateInterface $form_state)

      // doing nothing much here
      return $form;

Do i need to do something with _entity_form also?? Grateful for any feedback Mathew

2 Answers 2


Alternatively, you can use hook_entity_type_alter() to override the default form handler classes. It would be something like:

 * Implements hook_entity_type_alter().
function mymod_entity_type_alter(array &$entity_types){
  $entity_types['commerce_product']->setHandlerClass('form', array(
    'edit' => 'Drupal\mymod\Form\EventForm'

You need to change

$route->setDefault('_form', '\Drupal\mymod\Form\EventForm');


$route->setDefault('_entity_form', '\Drupal\mymod\Form\EventForm');

Otherwise the upcasting and other magical things are broken. See \Drupal\Core\Entity\Routing\DefaultHtmlRouteProvider::getEditFormRoute where it gets defined initially.

  • I spotted that earlier on and tried it but it gave me a Drupal\Component\Plugin\Exception\PluginNotFoundException: The "\Drupal\mymod\Form\EventForm" entity type does not exist. in Drupal\Core\Entity\EntityTypeManager->getDefinition() (line 130 of core\lib\Drupal\Core\Entity\EntityTypeManager.php). I assumed that it was still looking for an '<entity>.<operation>' format as in the getEditFromRoute, instead of the form path as in your suggestion?
    – Mathew
    Feb 12, 2016 at 20:13
  • ok so just tried the above with entity.comment.edit_form re routed to my form extending CommentForm this time. Just incase something in Product Entity setup is causing it to fail - but I am getting a access denied on trying to access edit form - confused?!
    – Mathew
    Feb 13, 2016 at 20:27

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