It depends entirely on whether you want the friendship relation to be
symmetric or not.
Symmetric: If Fred is Joe's friend then Joe is Fred's friend and vice-
versa
Asymmetric: Fred can be Joe's friend regardless of whether or not Joe
is Fred's friend.
An asymmetric relation would be easier to implement:
table: friendships (id, subject_id, object_id) [person `subject_id`
regards person `object_id` as a friend]
class Person extends AppModel {
var $hasAndBelongsToMany = array(
'Friend' => array( // People that this person regards as a friend
'className' => 'Person',
'with' => 'Friendship',
'foreignKey' => 'subject_id',
'associationForeignKey' => 'object_id'
),
'Admirer' => array( // People who regard this person as a friend
'className' => 'Person',
'with' => 'Friendship',
'foreignKey' => 'object_id',
'associationForeignKey' => 'subject_id'
)
);
}
Symmetric relationships would be trickier. As I see it, you'd have to
use a custom query to retrieve/update/delete the data, and always
enforce a constraint that (for example) subject_id < object_id [to
avoid duplicates].
Although perhaps you could act as if it was asymmetric, but
synchronize `friendship` table updates : if you create or delete
{subject_id: 1, object_id: 2} then you must simultaneously create/
delete {subject_id: 2, object_id: 1}. You'd get data duplication,
sure, but it might make things easier to manage.
Hope this helps - let me know how this progresses, as it's quite an
interesting subject.
On Apr 9, 10:06 am, dizz <[EMAIL PROTECTED]> wrote:
> Hi all,
>
> I'm trying to add a friend feature to one of my sites.
>
> I am trying to wrap my head around how to set up the relationship.
>
> I have a table users which holds all the users info.
>
> Each user can have many friends which is just an alias for many users
> and those friends (users) belong to the User.
>
> This sounds like a HABTM relation, but how would I go about setting it
> using the same model?
>
> Any help would be greatly appreciated.
>
> Thanks,
> -Andrew
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