Eager fetching with Sonata list view - doctrine-orm

Question

I'm using SonataAdmin and SonataDoctrineORMAdmin bundles to manage entities.
The problem is I can't figure out how to eager fetch the related entities in the list view and as the number of listed entities increase the number of queries executed increasing rapidly as well.
I tried adding `fetch="EAGER" to the relation annotations but the profiles show that Sonata executes the separate queries anyway.
Here's one relation worth of code:
Post
<?php
namespace Acme\AppBundle\Entity;
use Doctrine\ORM\Mapping as ORM;
use Doctrine\Common\Collections\ArrayCollection;
/**
* #ORM\Table()
* #ORM\Entity
*/
class Post
{
/**
* #ORM\Column(name="id", type="integer")
* #ORM\Id
* #ORM\GeneratedValue(strategy="AUTO")
*/
private $id;
/**
* #ORM\Column(name="name", type="string", length=255)
**/
private $name;
/**
* #ORM\ManyToMany(targetEntity="Acme\AppBundle\Entity\Tag", fetch="EAGER")
* #ORM\JoinTable(name="join_post_to_tag",
* joinColumns={#ORM\JoinColumn(name="post_id", referencedColumnName="id")},
* inverseJoinColumns={#ORM\JoinColumn(name="tag_id", referencedColumnName="id")}
* )
**/
private $tags;
public function getId()
{
return $this->id;
}
public function setName($names)
{
$this->name = $name;
return $this;
}
public function getName()
{
return $this->name;
}
public function setTags($tags)
{
$this->tags = $tags;
return $this;
}
public function __toString()
{
return $this->getName();
}
}
Tag
<?php
namespace Acme\AppBundle\Entity;
use Doctrine\ORM\Mapping as ORM;
/**
* #ORM\Table()
* #ORM\Entity
*/
class Tag
{
/**
* #ORM\Column(name="id", type="integer")
* #ORM\Id
* #ORM\GeneratedValue(strategy="AUTO")
*/
private $id;
/**
* #ORM\Column(name="value", type="string", length=255)
*/
private $value;
public function getId()
{
return $this->id;
}
public function setValue($value)
{
$this->value = $value;
return $this;
}
public function getValue()
{
return $this->value;
}
public function __toString()
{
return ($this->getValue()) ? : '';
}
}
The first related query that is run is fetching all the posts:
SELECT DISTINCT p0_.id AS id0, p0_.id AS id1
FROM Post p0_
LEFT JOIN join_post_to_tag j1_ ON p0_.id = j1_.post_id
LEFT JOIN Tag p1_ ON p1_.id = j1_.target_id
ORDER BY p0_.id ASC
But this does not fetch the related tags or even if it does, it still queries it again:
SELECT t0.id AS id1, t0.value AS value2
FROM Tag t0
INNER JOIN join_post_to_tag ON t0.id = join_post_to_tag.tag_id
WHERE join_post_to_tag.post_id = ?
I tried to mess with the createQuery method in the admin class but could not really find a way to make the related entities fetched correctly.
Is there a way to force the list view to eager fetch the required related entities?

Answer 1

You are on the right track, using the createQuery($context) method.
I have achieved eager loading as following:
public function createQuery($context = 'list')
{
$query = parent::createQuery($context); // let sonata build it's default query for the entity
$rootEntityAlias = $query->getRootAlias(); // get the alias defined by sonata for the root entity
$query->join($rootEntityAlias.'.relationFieldName', 'relationFieldAlias'); // manualy define the join you need
$query->addSelect('relationFieldAlias'); // this is the key line. It is not enough to join a table. You have to also add it to the select list of the query, so that it's actualy fetched
// $query->join(...) // repeat the process of joining and selecting for each relation field you need
// $query->addSelect(...)
return $query; // return the altered query to sonata. this will only work for the "list" action.
}
If you're having trouble using this, let me know:)
Further reads on this topic:
SO question
docs