Doctrine Mapping 2 Objects with 1 table

Question

Given i have 2 classes, User and UserId which look like this:

<?php

class UserId {
    /** @var int */
    private $value;

    public function __construct($value) {
        $this->value = (int) $value;
    }
}

class User {
    /** @var UserId */
    private $id;
    private $firstName;
    private $lastName;

    public function __construct(UserId $id, $firstName, $lastName) {
        $this->id = $id;
        $this->firstName = $firstName;
        $this->lastName = $lastName;
    }
}

Database:

User: 

id : INT PK
firstName: VARCHAR
lastName: VARCHAR

Is it possible to tell doctrine to generate me a User with a UserId when calling "find()"?

Answer 1

Yes, this is possible, I'll explain further on.

The simple way

First I have to say that for this simple use-case, the answer provided by Andresch Serj should suffice.

Set the UserId object using the constructor, get the UserId object by lazily instantiating it if it isn't present yet:

class User
{
    /**
     * @var UserId
     */
    private $userId;

    /**
     * @var int
     */
    private $id;

    /**
     * @param UserId $userId
     * ...
     */
    public function __construct(UserId $userId /* ... */)
    {
        $this->userId = $userId;
        $this->id     = $userId->getId();
        // ...
    }

    /**
     * @return UserId
     */
    public function getUserId()
    {
        if (!$this->userId) {
            $this->userId = new UserId($this->id);
        }

        return $this->userId;
    }

    // ...
}

The real answer

In order to manipulate an entity when it's loaded (fetched from the database) you could use Doctrine's PostLoad event.

First create a listener that will create a new UserId object and set it on the User entity:

use Doctrine\ORM\Event\LifecycleEventArgs;

class UserListener
{
    /**
     * @param  User               $user
     * @param  LifecycleEventArgs $event
     * @return void
     */
    public function postLoad(User $user, LifecycleEventArgs $event)
    {
        $userId = new UserId($user->getId());
        $user->setUserId($userId);
    }
}

Then refactor the getUserId() method of User to simple return the UserId object. Add a setUserId() method (it's wise to make sure an already present UserId object can't be swapped out). Also note the @EntityListeners annotation, which tells Doctrine there's a listener in place for this entity:

/**
 * @EntityListeners({"UserListener"})
 */
class User
{
    /**
     * @return UserId
     */
    public function getUserId()
    {
        return $this->userId;
    }

    /**
     * @param  UserId $userId
     * @return void
     * @throws RuntimeException
     */
    public function setUserId(UserId $userId)
    {
        if ($this->userId) {
            throw new RuntimeException("UsedId already present, you can't swap it!");
        }

        $this->userId = $userId;
    }

    // ...
}

Finally, in the configuration/bootstrap phase of your application you should register the listener:

$listener = new UserListener();
$em->getConfiguration()->getEntityListenerResolver()->register($listener);

Now, whenever a User entity is loaded by Doctrine, a UserId object will be inserted into it. This setup is very useful for more advanced use-cases than the one you described.

You can read more about this here and here.