如何在与Doctrine 2的manyToMany关联中多次添加相同的实体？

Question

In my Badges Entity, I have this manytomany association:

<?php

class Badges
{
    /**
     * @var integer
     *
     * @ORM\Column(name="id", type="integer", nullable=false, unique=true)
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="IDENTITY")
     */
    private $id;


    /**
     * Unidirectional - Many users have Many new Matches (OWNING SIDE)
     *
     * @var \Doctrine\Common\Collections\Collection
     *
     * @ORM\ManyToMany(targetEntity="Entity\Event", cascade={"persist"})
     */
    private $match;
}

Which takes an event and associate it to this badge. Many badges can have many events. That's ok.

Now my problem is that a Badge can have several time the same event. And doctrine 2 Does NOT like that and throw out an error. Something like "This relation (Badge_id - Event_id ) already exist.

How do I fix that ?

Many thanks

Answer 1

You can add to your relationship one more attribute count that will store number of duplicating pairs. And if record is already exist you can just increment count instead of trying to insert new row.

To define relationship with an attribute in Doctrine you need to define entity in the middle between your Badge and Event entities:

  +---------+          +---------+   
  |         |          |         |   
  |  Badge  |          |  Event  |   
  |         |          |         |   
  +--+------+          +------+--+   
     1                        1      
     |                        |      
     |   +---------------+    |      
     |   |               |    |      
     +-N-+  Badge_Event  +-N--+      
         |               |           
         +---------------+         

In Badge_Event entity you can define your new attribute count.