Trying to join two simple tables using Doctrine 2 - php

Question

I'm quite a beginner at Symfony 2 and Doctrine 2. I have two models a Blog post and Comment. They are related to each other by blog_id FK inside comment table.
I just want to create a simple method that takes a blog id, Retrieves that blog and related comments. Instead of doing another query in lazy-loading the related comments.
Here's what i tried :
<?php
namespace Blogger\BlogBundle\Entity\Repository;
use Doctrine\ORM\EntityRepository;
class BlogRepository extends EntityRepository
{
public function getBlogWithComments($id)
{
$query = $this->getEntityManager()->createQuery('
SELECT b, c
FROM BloggerBlogBundle:Blog b
WHERE b.id = :id
JOIN b.id c
WHERE b.id = c.blog');
$query->setParameter("id", $id);
return $query->getResult();
}
}
I'm really a beginner at Doctrine 2. I usually use Query Builder, But i have no idea how to make a join using it. So Tried it in DQL, Couldn't figure it out either.
It gives me this syntax error whenever i try to call getBlogWithComments method:
[Syntax Error] line 0, col 80: Error: Expected end of string, got
'JOIN'
All what i want to know is that, How to write JOIN statements using Query Builder and DQL ? Knowing that documentation is not that helpful unfortunately.

Answer 1

A JOIN with DQL is done by referencing the relationship between the entities and it only needs to go one way. What I mean is b.comment c is all that is needed, there is no need for referencing c.blog.
public function getBlogWithComments($id)
{
return $this->getEntityManager()
->createQuery('
SELECT b, c
FROM BloggerBlogBundle:Blog b
JOIN b.comment c
WHERE b.id = :id
')
->setParameter("id", $id)
->getResult();
}