How to define relationships when using interfaces - php

Question

The normal use of polymorphic relationships in Laravel is covered pretty well by the Post--User--Image example.
I'm trying to find a clean way to implement relationships for let's say an Article/ContentA/ContentB relationship.
articles
id
content_1
id
content_2
id
user_defined_content_n
id
contentables
article_id
contentable_id
contentable_type // content_2, user_defined_content_n
The content classes are not necessarily known by the article, so defining the article model with many MorphedByMany relationships is not how I want to do this.
Perhaps I am structuring my classes poorly. I could create a ContentEntity class which morphs to individual Content classes but I would like to avoid this if possible.
Maybe this better explains my problem.
class Article extends Model {
public function contentEntities() {
return $this->hasMany(ContentEntity::class);
}
}
class ContentEntity extends Model {
public function contentable() {
return $this->morphTo();
}
}
class Content extends Model {
public function contentEntity() {
return $this->morphOne(ContentEntity::class, 'contentable');
}
}
class Video extends Model {
public function contentEntity() {
$this->morphOne(ContentEntity::class, 'contentable');
}
}
This works but seems very unclean to me. I think it adds too much developer overhead to have to manage the ContentEntity parent.
Edit:
Unless someone provides a better solution, I went with an EAV style solution using ContentEntitys.

Answer 1

You could always extract the relationship to a trait for easier maintenance and extendability in the future:
Trait
trait Contentable
{
public function contentEntity() {
if(property_exists($this, 'contentable') && $contentable == 'many') {
return $this->hasMany(ContentEntity::class);
} else {
return $this->morphOne(ContentEntity::class, 'contentable');
}
}
// Future implementations
}
Then all you need to do is use the trait in various entities:
Models
class Content extends Model {
use Contentable;
}
class Video extends Model {
use Contentable;
}
class Article extends Model {
use Contentable;
protected $contentable = 'many';
}