my Doctrine association does not work properly - symfony

Question

Hiho,
what i want to achieve: i have Projects, and within Project-edit, there is a form where i can drop images on (with dropzone.js) and those images are saved and assigned to the given Project.
Image upload works, the Image entities are being saved to the images table and they have the right project_id. But if i access the Project Enity, "images" is "null" in the project array. not an Collection of Image Entites.
It looks like a simple private Variable with no default value.
I guess my OneToMany and ManyToOne associations don't seem to work.
Some Code:
Project.php
/**
* #var ArrayCollection
* #ORM\OneToMany(targetEntity="AppBundle\Entity\Image", mappedBy="project", cascade={"persist, remove"})
*/
private $images;
/**
* #return \Doctrine\Common\Collections\Collection
*/
public function getImages()
{
return $this->images;
}
public function addImage(Image $image)
{
$this->images[] = $image;
}
public function removeImage(Image $image) {
$this->images->removeElement($image);
}
Image.php
/**
* #var \AppBundle\Entity\Project
*
* #ORM\ManyToOne(targetEntity="AppBundle\Entity\Project", inversedBy="images")
* #ORM\JoinColumns({
* #ORM\JoinColumn(name="project_id", referencedColumnName="id")
* })
*/
private $project;
/**
* Set project
*
* #param \AppBundle\Entity\Project $project
*
* #return Image
*/
public function setProject(\AppBundle\Entity\Project $project = null)
{
$this->project = $project;
return $this;
}
/**
* Get project
*
* #return \AppBundle\Entity\Project
*/
public function getProject()
{
return $this->project;
}
Everything is saved to DB
but images is "null" (not an ArrayCollection :( )
Perhaps, there is something missing. But i dont see it somehow (although its soooo basic stuff)
Cheers
Adrian

Answer 1

Do the following in Project.php
In the constructor, add the following:
public function __construct()
{
// ...
$this->images = new ArrayCollection();
}
*Change addImage function to :
public function addImage(Image $image)
{
if(!$this-images->contains($image))
$this-images->add(image);
}
And then in Image.php, change setProject to:
public function setProject(\AppBundle\Entity\Project $project = null)
{
$this->project = $project;
if($project != null)
$project->addImage($this);
return $this;
}
Persist a few images and check if "Images" is not null.

Answer 2

I agree with Medard about the constructor and you also can try to set the fetch parameter to lazy on the oneToMany annotation.
Maybe a miss with the paramConverter

Answer 3

Oh Boy...
as i generated the Entities from DB (with doctrine:generate) there were Mapping files in the middle of the generating process (see http://symfony.com/doc/current/doctrine/reverse_engineering.html)
as soon as i deleted the src/AppBundle/Resources/config/doctrine folder (with orm.config.xml files in it) the Images were showing as persistent ArrayCollection.
but still the results where empty.
so i had to additionally put fetch="EAGER" into the OneToMany Mapping, as Lazyloading didnt seem to work properly (while dumping in twig, the result project.images was not initialized)
So thanks alot for your help. in the end, my images are showing up properly.
it would be nice, if symfony would write mapping errors in the dev.log, so i wouldnt have to search for 2 days.
Cya
Adrian