How to add extra WHERE clauses when retrieving relationships in Doctrine2 - php

Question

I have two entities Post and Comment.
Structure:
Post:
id
title
body
Comment:
id
post_id
body
active
class Post
{
/**
* #ORM\Column(name="id", type="integer")
* #ORM\Id
* #ORM\GeneratedValue(strategy="AUTO")
*/
private $id;
/**
* #ORM\Column(name="title", type="string", length=255)
*/
private $title;
/**
* #ORM\Column(name="body", type="text")
*/
private $body;
/**
* #ORM\OneToMany(
* targetEntity="Comment",
* mappedBy="post"
* )
*/
private $comments;
class Comment
{
/**
* #ORM\Column(name="id", type="integer")
* #ORM\Id
* #ORM\GeneratedValue(strategy="AUTO")
*/
private $id;
/**
* #ORM\Column(name="body", type="text")
*/
private $body;
/**
* #ORM\ManyToOne(
* targetEntity="Post",
* inversedBy="comments"
* )
* #ORM\JoinColumn(
* name="post_id",
* referencedColumnName="id"
* )
*/
private $post;
As a result when I want to get all comments for a post I use $post->getComments() and it works.
How I can add extra Where clauses into this relationship if I want to get only posts with active = 1.
I know that I can do it by DQL or queryBuilder but I want to know how I can do it by mapping

Answer 1

I think the cleanest way to retrieve only active comments is to use Doctrine's Criteria object in the getComments method of your Post entity
use Doctrine\Common\Collections\Criteria;
and
public function getComments()
{
$criteria = Criteria::create();
$criteria->where(Criteria::expr()->eq('active', 1));
return $this->comments->matching($criteria);
}
Edit
If you want to prevent multiple queries each time you retrieve the active comments, you'll need to store them in a local variable. Instead of modifying getComments, you could add $active_comments and getActiveComments, which will populate $active_comments and only query the db if $active_comments is false.
class Post {
private $active_comments;
public function getActiveComments()
{
if(!$this->active_comments) {
$criteria = Criteria::create();
$criteria->where(Criteria::expr()->eq('active', 1));
$this->active_comments = $this->comments->matching($criteria);
}
return $this->active_comments;
}