Doctrine Entities and traits. Right way - php

Question

I have a Comment entity (for user comments) and I want to add a new feature (Commentable) in my old entities.
I created a trait Commentable:
trait Commentable
{
/**
* List of comments
*
* #var Comment[]|ArrayCollection
*
* #ORM\OneToMany(targetEntity="Comment")
*/
protected $comments;
/**
* Constructor
*/
public function __construct()
{
$this->comments = new ArrayCollection();
}
/**
* Get Comments
*
* #return Comment[]|ArrayCollection
*/
public function getComments()
{
return $this->comments;
}
/**
* Add comment to the entity
*
* #param Comment $comment
*/
public function addComment(Comment $comment)
{
$this->comments->add($comment);
}
}
and in the old entities I do something like this:
class Image
{
use Commentable {
Commentable::__construct as private __commentableConstruct;
}
/** some stuff **/
}
The Comment class looks like:
class Comment
{
/**
* Identifier
*
* #var int
*
* #ORM\Id
* #ORM\Column(type="integer")
* #ORM\GeneratedValue(strategy="IDENTITY")
*/
protected $id;
/**
* Comment owner
*
* #var User
*
* #ORM\ManyToOne(targetEntity="User", inversedBy="comments")
* #ORM\JoinColumn(name="user_id", referencedColumnName="id")
*/
protected $user;
/**
* Comment content
*
* #var string
*
* #ORM\Column(type="text")
*/
protected $content;
/**
* #var Image
*
* #ORM\ManyToOne(targetEntity="Image", inversedBy="comments")
*/
protected $image;
/** all the classes using Commentable **/
/** some stuff */
}
I think the idea is not bad. I can create new behaviours and easily add it to entities.
But I don't like the idea on the Comment entity. Adding all the classes using the commentable trait is not 'usefull'.
I'm receiving this error... but I don't know how I can fix that with traits:
OneToMany mapping on field 'comments' requires the 'mappedBy' attribute.

Answer 1

I fixed the problem using
trait Commentable
{
/**
* List of comments
*
* #var Comment[]|ArrayCollection
*
* #ORM\ManyToMany(targetEntity="XXXX\Entity\Comment")
* #ORM\OrderBy({"createdAt" = "DESC"})
*/
protected $comments;
/**
* Constructor
*/
public function __construct()
{
$this->comments = new ArrayCollection();
}
/**
* Get Comments
*
* #return Comment[]|ArrayCollection
*/
public function getComments()
{
return $this->comments;
}
/**
* Add comment to the entity
*
* #param Comment $comment
*/
public function addComment(Comment $comment)
{
$this->comments->add($comment);
}
}

Answer 2

It's not a trait matter, it's a mapping / doctrine related problem.
Your annotation "#OneToMany" misses a configuration according to the documentation
I guess that in your Image class, you should overwrite the property that you use for mapping.