single-table-inheritance.md

Single Table Inheritance

The ORM provides the ability to store multiple model variations inside one table. In order to achieve that you must extend your parent entity and declare relations/columns specific to the child.

Definition

/** @Entity */
class Post
{
    /** @Column(type="primary") */
    public $id;
}

/** @Entity */
class Article extends Post
{
    /** @Column(type="string") */
    public $articleTitle;
}

You can store an Article the same way as the parent entity.

Note, ORM will create a special column in your entity table, _type, in which the child id will be stored.

Querying

You have to remember that fetching entities from the repository might return any of child entity:

// posts and articles
$posts = $orm->getRepository(Post:class)->findAll();

You are currently not allowed to assign custom repositories or constrains to child entities. However, you can use _type in your queries to pre-filter the selection.