Symfony 2 get Doctrine in Entity - symfony

Question

I have two classes
class Topic
{
protected $id;
//....
}
and
class Post
{
protected $topic_id;
//...
}
and I would like add method getPostCount() in Topic class. In other frameworks I used to use something like that:
public function getPostCount()
{
$count = Post::find()
->where(['topic_id' => $this->id])
->count();
return $count;
}
but in symfony2 I don't know how to make it.

Answer 1

You can create a repository class with this method. Add the repository class name to your entity's mapping definition, like this:
/**
* #ORM\Entity(repositoryClass="AppBundle\Repository\PostRepository")
*/
class Post
{
protected $topic_id;
//...
}
And in your repository class:
public function getPostCount($id)
{
$query = $this->createQueryBuilder('p')
->select('count(p.topic_id)')
->where('p.topic_id = :id')
->setParameter('id', $id)
->getQuery()->getSingleScalarResult();
return $query;
}

Answer 2

In addition to #DonCallisto answer
//Topic.php
public function getPostsCount()
{
return $this->getPosts()->count();
}
This use doctrine lazyloading: it could be done because you already defined the relation between the entity.
It would not be a good practice to do a query inside the entity, you should use a Repository for that.

Answer 3

//Topic.php
public function getPostsCount()
{
return $this->getPosts()->count();
}
If you have configured annotations or yml properly, you're fine with this

Answer 4

Into Post repository:
public function getPostCount($id) {
$qb = $this->getEntityManager()->createQueryBuilder();
$qb->select('count(p.topic_id)');
$qb->from('AppBundle:Post', 't')
->where('p.topic_id = :id')
->setParameter('id', $id);
$count = $qb->getQuery()->getSingleScalarResult();
return $count;
}