MN relationships in Doctrine

Question

ZF has a very nice feature which is called findManyToManyRowset which returns you directly a collection of objects from a MN connection. The whole purpose of MN is to get the information from the other table, not from the connection table.

We have this schema:

- users
  - id
  - name

- groups
  - id
  - name

- user_has_groups
  - user_id
  - group_id

I want to create a user function that will return directly a collection of group objects and not a collection of user_has_groups objects.

$user->UserHasGroups ;// returns a collection of user_has_groups
$user->Groups; // returns Doctrine_Record_UnknownPropertyException 

Is there a way to do this directly?

Answer 1

Doctrine handles this automatically assuming your schema is set up correctly. I only use Doctrine as part of Symfony, so my schema.yml would look something like this. You may need to alter it if your Doctrine install uses a different method to define your schema:

Users:
  columns:
    name:
      type: string
  relations:
    Groups:
      refClass: UserHasGroups
      local: user_id
      foreign: group_id

Groups:
  columns:
    name:
      type: string
  relations:
    Users:
      refClass: UserHasGroups
      local: group_id
      foreign: id

UserHasGroups
  columns:
    user_id:
      type: integer
      primary: true
    group_id:
      type: integer
      primary: true

Doctrine will use the UserHasGroups class as a many-to-many join table. Then, calling $user->Groups will get you all associated Groups objects.

As a side note, I would change your model names to the singular form, eg User, Group. $user = new Users() implies at first glance that you're creating multiple users in one go, which I presume you're not :-)

See the Doctrine join table docs for further details.