Extending entities in Symfony2 with Doctrine2

Question

I'm having trouble finding a way to appropriately extend an Entity across bundles in Symfony2 using Doctrine2 as the ORM.

Currently there are three methods that I've found to extending entities in Symfony2 using Doctrine2 as the ORM. Mapped Superclass, Single Table Inheritance and Class Table Inheritance. None of these work for what I'm looking to do.

I have two Bundles: UserBundle and BlogBundle. I want to be able to use the UserBundle in projects that do not have the BlogBundle, but the BlogBundle will always be used in projects that have the User Bundle. It's ok if the BlogBundle has dependencies on the UserBundle, but not the other way around.

I have two entities: BlogBundle\Entity\Post and UserBundle\Entity\User

Relationship: There needs to be a One to Many relationship between Users and Blog Posts. This is achieved through a Author_ID property (column) on the BlogBundle\Entity\Post object (table) which is mapped to UserBundle\Entity\User.id

The Problem: I can call the UserBundle\Entity\User entity directly from within the BlogBundle and achieve what I'm looking for using a Uni-Directional mapping. This does not allow me to access all posts by a user from within a User object. I can access the data via custom queries but this is not as clean as accessing posts by a user through the user object.

What I'd like to do is extend the UserBundle\Entity\User object from within the BlogBundle, and add the methods and properties to this object that establish the One to Many mapping used within the BlogBundle. None of this is persisted, it simply defines the relationship and allows me to logically access all posts created by a user in an application that implements both the BlogBundle and UserBundle by adding needed functionality to the User object within the blog bundle (thus avoiding a dependency from the UserBundle to the BlogBundle).

When I create a BlogBundle\Entity\User object and extend UserBundle\Entity\User I must declare @ORM\Table(name="usertablename"). If I don't, any attempt to access the BlogBundle\Entity\User object will fail to access the database. Since none of the additions in the extended object persist, this works fine across bundles. The issue with this is when I call "php app/console doctrine:schema:update --force", there is a conflict since two entities try to map to & create the same table. I have tried using the ResolveTargetEntityListener feature that was recently implemented but this, along with Mapped Superclas, STI and CTI all force a dependency on the BlogBundle from the UserBundle.

Below are my objects to help illustrate my my setup. They have been abbreviated for clarity. I realize some of the semantics aren't correct but it's intended to communicate the ideas & configuration.

UserBundle\Entity\User

@ORM\Table(name="app_user")
@ORM\Entity
class User implements UserInterface
{
    ...
}

BlogBundle\Entity\Post

@ORM\Table(name="app_post")
@ORM\Entity
class Post
{
    ...

    @ORM\Column(name="author_id", type="integer")
    protected $author_id;

    @ORM\ManyToOne(targetEntity="\App\BlogBundle\Entity\User", inversedBy="posts")
    @ORM\JoinColumn(name="author_id", referencedColumnName="id")
    protected $author;
}

BlogBundle\Entity\User

use App\UserBundle\Entity\User as BaseUser
@ORM\Entity
@ORM\table(name="app_user")
class User extends BaseUser
{
    ....

    @ORM\OneToMany(targetEntity="App\BlogBundle\Entity\Post", mappedBy="author")
    protected $posts;

    public function __construct()
    {
        parent::_construct();

        $this->posts = new \Doctrine\Common\Collections\ArrayCollection();
    }

    .... 
    /* Getters & Setters, nothing that defines @ORM\Column, nothing persisted */
}

This works but the problem is that I'm mapping two entities in the project to the same table. The extended object doesn't grab the @ORM\Table(name="app_user") from it's parent so it must be defined in BlogBundle\Entity\User. If not any reference to this object from a controller will not access the database. Since nothing is persisted from the extended object nothing is broken except for when I try to update the database schema from the console.

I can use a unidirectional relationship, but this limits how I can access the data from within a controller.

Answer 1

You can see in this link to know about inheritance: http://docs.doctrine-project.org/en/latest/reference/inheritance-mapping.html#single-table-inheritance

You must declare in UserBundle\Entity\User:

/**
 * @Entity
 * @InheritanceType("SINGLE_TABLE")
 * @DiscriminatorColumn(name="discr", type="string")
 * @DiscriminatorMap({"baseuser" = "UserBundle\Entity\User", "blogUser" = "BlogBundle\Entity\User"})
 */
class User implements UserInterface
{
    ...
}

And BlogBundle\Entity\User

use App\UserBundle\Entity\User as BaseUser;
/**
 * @ORM\Entity
 */
class User extends BaseUser
{
    ....
}

Goodluck!