Symfony2 (deserialize): update entity (with association) with json - php

Question

I got the serializer in Symfony working, i can GET and POST json with the EntityController. I have an edit form where an existing object/entity can be edited and saved. When the edited object gets posted (as a json object) the json objects gets deserialized, persisted and flushed tot the database. So far so good, at least as long as i dont post associated (ManyToMany) entities.
I have two entities (with a ManyToMany association):
Object
Element
This works (see also the jsonEditAction in the controller(posted below)):
{
"id": "1",
"name": "object 1"
}
My question is: How can i edit the object with associated entities in the json, like this:
{
"id": "1",
"name": "object 1",
"elements": {
"0": "1",
"1": "2"
}
}
When i post the above json i get the following notice from Symfony:
"message": "Expected argument of type \"AppBundle\Entity\Element\", \"integer\" given",
"class": "Symfony\Component\PropertyAccess\Exception\InvalidArgumentException",
For further information; this is the editAction where the Json is posted to:
public function jsonEditAction(Request $request, $id) {
$serializer = $this->initSerializer();
$em = $this->getDoctrine()->getManager();
$object = $em->getRepository('AppBundle:Object')->findOneById($id);
$data = $request->getContent();
$serializer->deserialize($data, 'AppBundle\Entity\Object', 'json', array('object_to_populate' => $object));
try {
$em->persist($object);
$em->flush();
$view = $this->view($object, 200)
->setTemplate("object/json.html.twig");
} catch (Exception $e) {
$view = $this->view('Caught exception: ' . $e->getMessage() . "\n", 500)
->setTemplate("object/json.html.twig");
}
return $this->handleView($view);
}
private function initSerializer() {
$encoders = array(new JsonEncoder());
$normalizers = array(new ObjectNormalizer());
$serializer = new Serializer($normalizers, $encoders);
return $serializer;
} `
Should i walk to the array with elements and find them one by one and then add them to the 'object' entity? Or is there a 'build-in' solution in the serializer that i missed/ didn't see?
UPDATE:
Also the JSON like suggested by Alexey didn't work:
{
"id": 2,
"name": "Object 2c",
"elements": [{
"id": 1
}, {
"id": 2
}]
}
UPDATE:
My question is a duplicate of:
Deserialize an entity with a relationship with Symfony Serializer Component
There is a pull request created and will be merged in Symfony 3.2...

Answer 1

You have a bad JSON, Symfony says you the same.
A good JSON can look like this:
{
"id": "1",
"name": "object 1",
"elements": [
{"id": "254", "name": "element 254"},
{"id": "301", "name": "element 301"}
]
}
Symfony tries to deserialize an Element object from "1" and "2" in your original JSON and fails.