Fix form submit @id without breaking success handler entity results

item_uri_template on the submit operations polluted the normalization
context when a success handler replaced the Form result with a different
entity (e.g. User on registration), producing wrong @type/@id for that
entity.

Instead: remove item_uri_template and strip the /submit suffix from @id
in onPostRespond, which only affects the @id field and leaves the result
entity unchanged. Registration test restored to expect the User entity.

Author: silverbackdan

features/user/register_form.feature

@@ -27,7 +27,19 @@ Feature: Register process via a form
     And the response status code should be 201
     And the response should be in JSON
     And the header "Content-Type" should be equal to "application/ld+json; charset=utf-8"
-    And the JSON should be valid according to the schema file "form.schema.json"
+    And the JSON should be a superset of:
+    """
+    {
+        "@context": "/contexts/User",
+        "@type": "User",
+        "username": "new_user",
+        "emailAddress": "user@example.com",
+        "_metadata": {
+          "persisted": true
+        }
+    }
+    """
+    And the JSON should be valid according to the schema file "user.schema.json"
     And I should get a "user_welcome" email sent
 
   Scenario Outline: Submit a duplicate user registration form

src/Entity/Component/Form.php

@@ -52,7 +52,6 @@
             write: false,
             serialize: true,
             requirements: ['id' => '[^/]+'],
-            normalizationContext: ['item_uri_template' => '/forms/{id}{._format}'],
         ),
         new Post(
             name: '_api_/forms/{id}/submit{._format}_post',
@@ -63,7 +62,6 @@
             write: false,
             serialize: true,
             requirements: ['id' => '[^/]+'],
-            normalizationContext: ['item_uri_template' => '/forms/{id}{._format}'],
         ),
     ]
 )]

src/EventListener/Api/FormApiEventListener.php

@@ -68,11 +68,7 @@ private function handleFormData(ViewEvent $event): void
 
         if ($data->formView->getForm()->isValid()) {
             $result = $this->formSubmitHelper->handleSuccess($data);
-            // Only replace the Form with the result if it is an explicit Response object
-            // (e.g. a 404 from PasswordUpdateListener). Entity results (e.g. the created User
-            // from registration) are intentionally ignored — the submit endpoint always returns
-            // the Form entity so @type and @id remain stable regardless of side-effects.
-            if ($result instanceof Response) {
+            if ($result) {
                 $data = $result;
             }
         }
@@ -103,13 +99,25 @@ public function onPostRespond(ResponseEvent $event): void
             return;
         }
 
+        $response = $event->getResponse();
+
         if ($formView = $data->formView) {
             $form = $formView->getForm();
-            $response = $event->getResponse();
             if (!$form->isValid()) {
                 $response->setStatusCode(Response::HTTP_UNPROCESSABLE_ENTITY);
             }
         }
+
+        // AP4 uses the submit operation's uriTemplate to generate @id, giving /{uuid}/submit.
+        // Strip the suffix so @id always points to the canonical resource IRI.
+        $content = $response->getContent();
+        if ($content && str_contains($content, '\/submit"')) {
+            $decoded = json_decode($content, true);
+            if (isset($decoded['@id']) && str_ends_with($decoded['@id'], '/submit')) {
+                $decoded['@id'] = substr($decoded['@id'], 0, -\strlen('/submit'));
+                $response->setContent(json_encode($decoded));
+            }
+        }
     }
 
     private function getData(Request $request): ?Form