symfony2从object创建json

Hi I am trying to generate json as response using symfony2.

Here is my code.

/**
 * @Route("/viewComments/{taskId}")
 *
 */
public function viewCommentsAction($taskId)
{
    $commentsList = $this->getDoctrine()->getRepository("AppBundle:Comments")
                                        ->findBy(array("task" => $taskId));
    if (!$commentsList) {
        throw $this->createNotFoundException("non comments to show");
    }
    $serializer = $this->get('serializer');
    $json = $serializer->serialize(
                                $commentsList,
                                'json', array('groups' => array('group1'))
    );
    return new Response($json);

}

unfortunately I am getting response:

[[],[],[],[]]

Any suggestions?

Try this, creates a file: CommentRepository

class CommentRepository extends EntityRepository
{
    public function findCommentsList($id)
    {
        $query = $this->getEntityManager()->createQuery('YOUR QUERY HERE');
        ...

        return $query->getArrayResult();
    }
}

as you can see, I return an Array and now you can see values on the response. Later, changes the next line in your Action Controller:

...
$commentsList = $this->getDoctrine()->getRepository("AppBundle:Comments")
                                        ->findCommentsList($taskId));
...

Note: You should call your entities in singular