Has_many conversely

Rails
1

I have a very simple association:
class User < ActiveRecord::Base
has_and_belongs_to_many :friends,
:class_name=>“User”,
:join_table=>“friends_users”,
:association_foreign_key=>“friend_id”,
:foreign_key=>“user_id”

User.friends - returns my friends. How can i get users who “friended”
me?
Thanks.

2

Add a similar habtm to Friend ?

Fred

3

FriendUser.find(:all, :conditions => [‘friend_id = ?’,user.id
]).collect{|x|x.user}

so I think you can put that in a model function

def befriended_ones
FriendUser.find(:all, :conditions => [‘friend_id = ?’,user.id
]).collect{|x|x.user}
end

I would like to know if there is a way of doing this just using
associations…

4

Right, Ivor. I knew about this way, and also would like to know if
there is a way to do it through associations. And another issue, i
have rich join model via has_many :through. And collection’s clear
(user.groups.clear) method works strange. It just clears collection in
memory and doesn’t touch join table at all. Even not nullify foreign
keys, nothing. Is it expected?

5

Did you try reversing the habtm relationship manually:
has_and_belongs_to_many :friended,
:class_name => “User”
:join_table => “friends_users”,
:association_foreign_key => “user_id”,
:foreign_key => “friend_id”

You could build a plugin or function that did both ways, if you use
self-relations like this often. Otherwise, I don’t know anything
built into Rails that does it both ways.

  • Hal
6

It’s really simple! How i didn’t come to this from the beginning. From
the 1st sight i think it should work.
P.S fast test shows - it really works.

7

Kane,
I would appreciate it if you could give this a spin and let me know if
it
worked.
thanks
Ivor