Symfony2 Many to one - one to many without join table - symfony

Question

I have "Project" entity which can have several Benefits, while a benefit belongs to just one Project:
To me it seems a many to one - one to many relationship.
I followed the indication here
The Project entity is:
/**
* #ORM\Entity(repositoryClass="AppBundle\Entity\ProjectRepository")
* #ORM\Table(name="projects")
*/
class Project
{
/**
* #ORM\Column(type="integer")
* #ORM\Id
* #ORM\GeneratedValue(strategy="AUTO")
*/
protected $id;
/**
* #ORM\oneToMany(targetEntity="Benefit", mappedBy="project")
*/
protected $benefits;
/**
* Constructor
*/
public function __construct()
{
$this->benefits = new \Doctrine\Common\Collections\ArrayCollection();
}
// other stuff
/**
* Add benefits
*
* #param \AppBundle\Entity\Benefit $benefits
* #return Project
*/
public function addBenefit(\AppBundle\Entity\Benefit $benefits)
{
$this->benefits[] = $benefits;
return $this;
}
/**
* Remove benefits
*
* #param \AppBundle\Entity\Benefit $benefits
*/
public function removeBenefit(\AppBundle\Entity\Benefit $benefits)
{
$this->benefits->removeElement($benefits);
}
/**
* Get benefits
*
* #return \Doctrine\Common\Collections\Collection
*/
public function getBenefits()
{
return $this->benefits;
}
}
The benefit entity is:
/**
* #ORM\Entity(repositoryClass="AppBundle\Entity\BenefitRepository")
* #ORM\Table(name="benefits")
*/
class Benefit
{
/**
* #ORM\Column(type="integer")
* #ORM\Id
* #ORM\GeneratedValue(strategy="AUTO")
*/
protected $id;
// Other relevant fields
/**
* #ORM\ManyToOne(targetEntity="Project", inversedBy="benefits")
*/
protected $project;
In my controller I was hoping to do:
$project = $em->getRepository('AppBundle:Project')->findOneById(3);
$benefit = new Benefit();
// set some fields for the new Benefit
$benefit->setProject($project);
$em->persist($benefit);
and I was hoping to see the benefits as a collection inside the project entity doing:
$benefits = $project->getBenefits();
But it did not work, so I explicitely did:
$project->addBenefit($benefit);
$em->persist($project);
$benefits = $project->getBenefits();
And I indeed see new the newly created Benefit inside the collection inside project. The problem is that if I rerun this and add a new benefit to the same project, I just get the last one. Of course if in the same portion of code I create 2 benefits and add both, I have a collection of 2, but that's not what I want. On the Benefit side everything is ok: each new Benefit is persisted, all of them correctly pointing to the same Project.
What am I missing?
EDIT:
Here are the steps I make/stuff I checked:
The DB is in sync with the current entity metadata.
The updated Project entity is:
<?php
// src/AppBundle/Entity/Project.php
namespace AppBundle\Entity;
use Doctrine\ORM\Mapping as ORM;
/**
* #ORM\Entity(repositoryClass="AppBundle\Entity\ProjectRepository")
* #ORM\Table(name="projects")
*/
class Project
{
/**
* #ORM\Column(type="integer")
* #ORM\Id
* #ORM\GeneratedValue(strategy="AUTO")
*/
protected $id;
/**
* #ORM\oneToMany(targetEntity="Benefit", mappedBy="project", cascade="persist")
*/
protected $benefits;
/**
* Constructor
*/
public function __construct()
{
$this->benefits = new \Doctrine\Common\Collections\ArrayCollection();
}
// Other irrelevant fields
/**
* Add benefits
*
* #param \AppBundle\Entity\Benefit $benefit
* #return Project
*/
public function addBenefit(\AppBundle\Entity\Benefit $benefit)
{
$this->benefits[] = $benefit;
$benefit->setProject($this);
return $this;
}
/**
* Remove benefits
*
* #param \AppBundle\Entity\Benefit $benefits
*/
public function removeBenefit(\AppBundle\Entity\Benefit $benefits)
{
$this->benefits->removeElement($benefits);
}
/**
* Get benefits
*
* #return \Doctrine\Common\Collections\Collection
*/
public function getBenefits()
{
return $this->benefits;
}
}
Note that the removeBenefit is probably not properly implemented, but for the moment it's not relevant.
I clean the Benefit table.
I create a new benefit and attach to the a Project:
$em = $this->getDoctrine()->getManager();
$project = $em->getRepository('AppBundle:Project')->findOneById(3);
$benefit = new Benefit();
$benefit->setName('Name of the benefit');
// here I set other irrelevant fields
$project->addBenefit($benefit);
$em->persist($project);
$em->flush();
The Benefit gets properly persisted to DB. It properly links to the Project:
I then comment all the code in the controller and simply perform:
$em = $this->getDoctrine()->getManager();
$project = $em->getRepository('AppBundle:Project')->findOneById(3);
$benefits = $project->getBenefits();
return $this->render('testBenefits.html.twig', array(
'benefits' => $benefits, 'project' => $project));
If I dump $project I get:
And of course if I dump $benefits I get this:

Answer 1

You are not setting project in your benefit class.
public function addBenefit(\AppBundle\Entity\Benefit $benefit)
{
$this->benefits[] = $benefit;
$benefit->setProject($this); // Add this
return $this;
}
Noticed that I also changed your argument from benefits to benefit as addBenefit deals with one benefit object at a time.