Question

I’m trying to create a social-network like feature in an app I’m building, and Want to associate a Friend with another Friend.

Assume I have this:

Friend:
  connection: doctrine
  tableName: friend
  columns:
    id:
      type: integer(8)
      primary: true
      autoincrement: true
    name:
      type: string(75)
      notnull: true

How do I create a many to many relationship to associate Friend with itself?

Thanks ahead of time for your help..

Answer 1

Use self-referencing equal nest relations.

From the docs:

Equal Nest Relations

Equal nest relations are perfectly
suitable for expressing relations
where a class references to itself and
the columns within the reference class
are equal.

This means that when fetching related
records it doesn’t matter which column
in the reference class has the primary
key value of the main class.

The previous clause maybe hard to
understand so lets take an example. We
define a class called User which can
have many friends. Notice here how we
use the ‘equal’ option.

// models/User.php

class User extends BaseUser
{
    public function setUp()
    {
        parent::setUp();

        // ...

        $this->hasMany('User as Friends', array(
                'local'    => 'user1',
                'foreign'  => 'user2',
                'refClass' => 'FriendReference',
                'equal'    => true,
            )
        );
    }
}
// models/FriendReference.php
class FriendReference extends Doctrine_Record
{
    public function setTableDefinition()
    {
        $this->hasColumn('user1', 'integer', null, array(
                'primary' => true
            )
        );

        $this->hasColumn('user2', 'integer', null, array(
                'primary' => true
            )
        );
    }
}

Here is the same example in YAML format. You can read more about YAML in the YAML Schema > Files chapter:

---
# schema.yml

# ...
User:
# ...
  relations:
    # ...
    Friends:
      class: User
      local: user1
      foreign: user2
      refClass: FriendReference
      equal: true

FriendReference:
  columns:
    user1:
      type: integer
      primary: true
    user2:
      type: integer
      primary: true