Adding a timestamp property to a relation in Symfony2 - doctrine-orm

Question

I am trying to model a simple comment system with 2 entities - User and Post. The User class has the regular properties, and the Post class looks like this:
class Post
{
/**
* #var integer $id
*
* #ORM\Column(name="id", type="integer")
* #ORM\Id
* #ORM\GeneratedValue(strategy="AUTO")
*/
private $id;
/**
* User who posted activity
*
* #var User
* #ORM\ManyToOne(targetEntity="Acme\AppBundle\Entity\User")
*/
protected $user;
/**
* #var string $text
*
* #ORM\Column(name="text", type="string", length=255)
*/
private $text;
/**
* #var datetime $timestamp
*
* #ORM\Column(name="timestamp", type="datetime")
*/
private $timestamp;
}
I need to make a simple association - Users can favourite posts. The logical thing to do would be to add ManyToMany association in User class to Post like so
#ORM\ManyToMany(targetEntity="Post")
Which would then create a mapping table with user_id and post_id as primary keys. Now my problem is that I need to add a timestamp property to track when the user liked a post. One possibility is to create a new Entity "FavouritePost", map it to both User and Post class using ManyToOne association, and add a timestamp property to it.
1) Is this the right/only way to do it in Symfony2?
2) If I want to select the most recent 15 posts, and check if the currently logged in user has liked the posts, how can I write a query for that?
Any help appreciated, as I am drawing a blank on how to do it via Symfony

Answer 1

1) Yes you may create a jointure table, and so its FavouritePost entity.
2) You should use a Repository to create all special queries :
#ORM\Entity(repositoryClass="Acme\AppBundle\Repository\FavouritePostRepository")
Then it's easy Doctrine queries, like you will make much more.