Render a many-to-many relation with extra fields into a form

Question

I'm wondering what is the best way to create a form that handle a many-to-many relation with extra field in symfony2.

For the example let's say I would like to create a notifying feature for users. I have the User and the Notification entities. Also in order to be able to add extra parameters in the many-to-many relation between entities, I created a third entity UserNotification. The extra parameter indicates if the notification has been read or not by the users.

* @ORM\Entity() */
class Notification
{
    /** @Id @Column(type="integer") */
    private $id;

    /** @OneToMany(targetEntity="UserNotification", mappedBy="notification") */
    private $usernotifications;

    /** @Column() */
    private $message;

    ...
}

* @ORM\Entity() */
class User
{
    /** @Id @Column(type="integer") */
    private $id;

    /** @OneToMany(targetEntity="UserNotification", mappedBy="user") */
    private $usernotifications;

    /** @Column() */
    private $name;

    ...
}

* @ORM\Entity() */
class UserNotification
{
    /** @ManyToOne(targetEntity="User", inversedBy="usernotifications")
    private $user;

    /** @ManyToOne(targetEntity="Message", inversedBy="usernotifications")
    private $message;

    /** @Column(type="boolean") */
    private $isRead;

    ...
}

This way I am able to get this kind of data

      User
+----+---------+
| id | name    |
+----+---------+
|  1 | John    |
|  2 | Paul    |
+----+---------+

      Notification
+----+----------------------+
| id | message              |
+----+----------------------+
|  1 | Cool stuff           |
|  2 | Lorem ipsum          |
+----+----------------------+

      UserNotification
+---------+-----------------+---------+
| user_id | notification_id | isRead  |
+---------+-----------------+---------+
|  1      |              1  |       1 |
|  2      |              1  |       0 |
|  1      |              2  |       0 |
|  2      |              2  |       1 | 
+---------+-----------------+---------+

Ok now here is the problem, how to make a form which allow to send a notification to some users? With a classic many-to-many relation it was not a problem. I had a NotificationType with the following builder:

    $builder->add('users', 'entity', array(
                'class' => 'User',
                'property' => 'name',
                'multiple' => 'true',
            ))
            ->add('message', 'text');

But since I had to create the intermediate UserNotification entity, I have no idea how to do it. Thanks for your help ;)

Answer 1

I did exactly the same. My InternalMessage entity is your Notification. In the form, users field is not mapped (property_path is false) and it's validated using a subscriber:

public function buildForm(FormBuilder $builder, array $options)
{
    $builder
        ->add('title', 'text', array(
            'label' => 'Titolo *'
        ))
        ->add('content',  'textarea', array(
            'label' => 'Contenuto *'
        ))
        ->add('priority', new PriorityType(), array(
            'label' => 'Priorità *'
        ))
        ->add('users', 'entity', array(
            'label'         => 'Destinatari *',
            'class'         => 'Acme\HelloBundle\Entity\User',
            'property'      => 'select_label',
            'multiple'      => true,
            'expanded'      => true,
            'property_path' => false,
        ));
    ;

    $builder->addEventSubscriber(new AddUsersValidationSubscriber());
}

While in my controller, the only thing i have to do (assuming that form is valid) is to create one InternalMessageFeedback entity (the same as your UserNotification) fore each user in form model:

$message = new InternalMessage();
$form    = $this->createForm(new InternalMessageType(), $message);

// ...

// The sender
$message->setUser($this->getSecurityContext()->getToken()->getUser());

// Persist the inverse side
$em = $this->getEntityManager();
$em->persist($message);

// One feedback for each user
/** @var $user \Acme\HelloBundle\Entity\User */
foreach($form->get('users')->getData() as $user) {
    $feedback = new InternalMessageFeedback();

    // Se the message and user for current feedback
    $feedback->setInternalMessage($message);
    $feedback->setUser($user);

    // Persist the owning side
    $em->persist($feedback);

    // Sync the inverse side
    $message->addInternalMessageFeedback($feedback);
}

$em->flush();

Hope this helps :)