Creating a "friends" association?


#1

Hi, I have a Friend model that looks like this:

create_table “friendships”, :force => true do |t|
t.column “sent_by_user_id”, :integer
t.column “received_by_user_id”, :integer
t.column “status”, :boolean
end

I would like to be able to define a :friends association in my user
model that returns friendships that are both sent_by and received_by a
given user. Any way to do this?

I’ve been told that traditionally you just create two friendship
records to handle this, but it seems like a cumbersome solution.

Thanks,

Andrew


#2

check out plugin acts as friends at agileweb.


#3

[I sent this a few hours ago but have not receive it back, please excuse if you got it twice.]

On Apr 24, 2007, at 6:13 PM, removed_email_address@domain.invalid wrote:

model that returns friendships that are both sent_by and received_by a
given user. Any way to do this?

I’ve been told that traditionally you just create two friendship
records to handle this, but it seems like a cumbersome solution.

That’s the canonical solution if it’s OK for the amount of data,
otherwise you need to emulate symmetry by hand:

sender.friends
receiver.friends

should contain each other and the nice way to do that is to delegate
in AR. That symmetry is then maintained by callbacks on the join model.

Additionally, you normally want to apply transitive somehow and the
SQL is easier if you have a “direction” to follow, I wrote a little
about this here:

http://www.advogato.org/article/914.html

– fxn


#4

On Apr 24, 2007, at 6:13 PM, removed_email_address@domain.invalid wrote:

model that returns friendships that are both sent_by and received_by a
given user. Any way to do this?

I’ve been told that traditionally you just create two friendship
records to handle this, but it seems like a cumbersome solution.

That’s the canonical solution if it’s OK for the amount of data,
otherwise you need to emulate symmetry by hand:

sender.friends
receiver.friends

should contain each other and the nice way to do that is to delegate
in AR. That symmetry is then maintained by callbacks on the join model.

Additionally, you normally want to apply transitive somehow and the
SQL is easier if you have a “direction” to follow, I wrote a little
about this here:

http://www.advogato.org/article/914.html

– fxn