Symfony2: Doctrine does not load related entities in many-to-many relation - php

Question

I have a many-to-many-relation, and when I load an entity that is on one side this relation, I expect to see as its property the ArrayCollection of related entities on another side. However, this does not happen - the ArrayCollection loaded has no elements in it, while in the database I can see the related entries. What could be the reason?
Here is my code:
One side of the relation, ConsolidatedReport class:
/**
* #var ArrayCollection
*
* #ORM\ManyToMany(targetEntity="P24\Response", inversedBy="consolidatedReports")
* #ORM\JoinTable(name="con_rprt_responses")
*/
private $responses;
Another side of the relation, Response class:
/**
* #var ArrayCollection
*
* #ORM\ManyToMany(targetEntity="P24\ConsolidatedReport\ConsolidatedReport", mappedBy="responses")
*/
private $consolidatedReports;
Here is the function I run to get an instance of ConsolidatedReport. This function sits inside a service that is being called from container:
/**
* Picks the consolidated report with given id.
*
* #param string $id
*
* #return ConsolidatedReport
*
* #throws NonExistentConsolidatedReportException if the survey doesn't exist
*/
public function pick($id)
{
$report = $this->repository->findOneBy(array('id' => $id));
if (!$report) {
throw new NonExistentConsolidatedReportException($id);
}
return $report;
}'
In the database, there is "con_rprt_responses" table with two columns "consolidated_reports_id" and "response_id". However, in profiler I do not see any queries to that table.
What could go wrong here?
UPDATE:
Please see my answer to this question below, that worked for me.

Answer 1

I added fetch="EAGER" to the $responses property of ConsolidatedReport class, and it worked.
The code now looks like this:
/**
* #var ArrayCollection
*
* #ORM\ManyToMany(targetEntity="P24\Response", inversedBy="consolidatedReports", fetch="EAGER")
* #ORM\JoinTable(name="con_rprt_responses")
*/
private $responses;
More info here:
http://doctrine-orm.readthedocs.org/en/latest/reference/working-with-objects.html#by-eager-loading
Still if someone knows why the collection of related entity would not load without explicitly specifying EAGER fetching - please share your knowledge, it is highly appreciated!

Answer 2

If you specify the joinColumns, does this solve your problem?
/**
* #ORM\ManyToMany(targetEntity="P24\Response", inversedBy="consolidatedReports")
* #ORM\JoinTable(name="con_rprt_responses",
* joinColumns={#ORM\JoinColumn(name="consolidated_reports_id", referencedColumnName="id")},
* inverseJoinColumns={#ORM\JoinColumn(name="response_id", referencedColumnName="id")}
* )
*/

Answer 3

The *toMany properties have to be initialized with an ArrayCollection.
public function __construct() {
$this->responses = new \Doctrine\Common\Collections\ArrayCollection();
$this-> consolidatedReports = new \Doctrine\Common\Collections\ArrayCollection();
}

Answer 4

In case you have more then single query to fetch the same objects using Doctrine try to use:
$entityManager->clear();
in between, to fix "missing" entities. It isn't solution "as is", however can give you an idea something wrong in chain of your queries.