Manually save a many to many relation in Doctrine - symfony1

Question

I have just created a new project with a many-to-many relation (User-Group) and the code below.
As you can guess in the code I'm trying to assign manually groups to a user, but it doesn't assign it anything...any idea?
User:
columns:
id:
type: integer(4)
autoincrement: true
primary: true
username:
type: string(255)
password:
type: string(255)
attributes:
export: all
validate: true
Group:
tableName: group_table
columns:
id:
type: integer(4)
autoincrement: true
primary: true
name:
type: string(255)
relations:
Users:
foreignAlias: Groups
class: User
refClass: GroupUser
GroupUser:
columns:
group_id:
type: integer(4)
primary: true
user_id:
type: integer(4)
primary: true
relations:
Group:
foreignAlias: GroupUsers
User:
foreignAlias: GroupUsers
The code is this:
public function executeIndex(sfWebRequest $request)
{
$user = Doctrine_Core::getTable('User')->find(1);
$groups = Doctrine_Core::getTable('Group')->findAll();
$user->setGroups($groups);
$user->save();
$this->forward('default', 'module');
}

Answer 1

Try defining the relation in the User entity too (and don't using foreingAlias in Groups). Also use the local and foreign fields.
So, schema.yml should look like:
User:
...
relations:
Groups:
class: Group
refClass: GroupUser
local: user_id
foreign: group_id
Group:
...
relations:
Users:
class: User
refClass: GroupUser
local: group_id
foreign: user_id
If that doesn't work, I think you can set the groups with the Doctrine "link" method.
See Record.php (probably in lib/vendor/symfony/lib/plugins/sfDoctrinePlugin/lib/vendor/doctrine/Doctrine folder)
Example:
$groups_ids = array();
foreach($groups as $group) $groups_ids[] = $group->getId();
$user->link('Groups',$groups_ids);
Also, if you are trying only to add instances to that relation (and you hate the person who will fix your code in the future) you can create N-GroupUsers
Example:
foreach($groups as $group) {
$ug = new GroupUser();
$ug->setUserId($user->getId());
$ug->setGroupId($user->getId());
$ug->save();
}
Please, use the first option and let me know if any of this works for you!