Inheritance & Association - doctrine-orm

Question

I need media entities defined like this:
Category:
name : string (25)
slug : string (25)
description: text
documents : associaion with Document
Document = #ORM\InheritanceType("SINGLE_TABLE"):
category : association (Category) and discriminator
title : string (50)
description: text
slug : string (50)
For example, categories:
VIDEO:
youtube
dailymotion
vimeo
PHOTO:
locale photo
cloud photo
FILE:
locale file
cloud file
A document of a category would be an instance of Document\Youtube etc ...
Is it possible to use a column as association field and discriminator for inheritance ?

Answer 1

The official documentation doesn't seem to mention a restriction about this.
However, as the column you want is a relation, the discriminator map would then rely on DB-issued IDs, which is not good in my opinion...
But you still can let Doctrine handle the discriminator for you: just declare a discriminator column you'll never use directly, declare its map, then rely on the entity logic to keep coherence between the category and the document type:
/**
* #ORM\Entity(repositoryClass="...
* #ORM\InheritanceType("SINGLE_TABLE")
* #ORM\DiscriminatorColumn(name="type", type="string")
* #ORM\DiscriminatorMap({
* "youtube"="Youtube",
* "dailymotion"="Dailymotion",
* ...
* })
*/
abstract class Document {
/**
* #ORM\ManyToOne(targetEntity="Category", inversedBy="documents")
*/
protected $category;
...
//this is to be called by children that all share a category field
public function setCategory(Category $c) {
$class = get_class($this);
if (strtolower($c->getName()) !== strtolower(substr($class, strrpos($class, '\\') + 1))) {
throw new \LogicException("Cannot bind " . $class . " to category " . $c->getName());
}
$this->category = $c;
return $this;
}