Simple Association Issue

Rails
1

Hi There,

Im trying to get my head around a model association issue that I’ve been
struggling with despite the fact that I know I’ve done the exact same
thing previously.

I have the following models:

class User < ActiveRecord::Base

has_many :user_mailboxes

end

class UserMailbox < ActiveRecord::Base

belongs_to :user

end

This all works fine and user maps to usermailbox through user_id.

The problem Im having is that the usermailbox table also has a
“other_user_id” field which also links back to the users table. I cannot
for the life of me figure out how I set this up in the model so that i
would be able to call something along the lines of:

for item in @user.user_mailboxes

item.other_user.first_name

end

So in essence my issue is that I have two fields in one table pointing
back at the same table and need to setup associations.

Any help would be greatly appreciated.

Cheers,
Chris

2

There was recently a discussion of exactly the same scenario here:

http://www.ruby-forum.com/topic/969712

That should answer your question.

3

Hi Fred,

So that means in my user model I can associate by using the following?

belongs_to :other_user, :class_name => “UserMailbox”

But what about when I want to go back the other way? So I have the
mailbox object which has the field “other_user_id” but how do I create
the association between this ID and the ID in the users table which is
its primary key (id)?

Chris

4

On 1 Feb 2011, at 17:51, Chris G. [email protected] wrote:

end

So in essence my issue is that I have two fields in one table pointing
back at the same table and need to setup associations.

belongs_to :foo, :class_name => ‘Bar’ creates an association with Bar
usin foo_id as the foreign key

Fred

5

On 1 February 2011 23:01, Chris G. [email protected] wrote:

Hi Fred,

Please quote the previous message so that the thread is easier to
follow.

So that means in my user model I can associate by using the following?

belongs_to :other_user, :class_name => “UserMailbox”

But what about when I want to go back the other way? So I have the
mailbox object which has the field “other_user_id” but how do I create
the association between this ID and the ID in the users table which is
its primary key (id)?

Did you read through the thread referenced by Robert? Did you work
right through and understand everything there? (Particularly note the
use of foreign_key).

Colin

6

Sure did:

class User < ActiveRecord::Base

has_many :user_mailboxes
belongs_to :other_user, :class_name => “UserMailbox”
end

class UserMailbox < ActiveRecord::Base

belongs_to :user
belongs_to :other_user, :class_name => “User”
end

Very helpful guys,

Thanks,
Chris

7

On 2 February 2011 22:04, Chris G. [email protected] wrote:

Sure did:

Sure did what? Please quote the previous post so each message makes
sense.

class User < ActiveRecord::Base

has_many :user_mailboxes
belongs_to :other_user, :class_name => “UserMailbox”

That does not look right.

end

class UserMailbox < ActiveRecord::Base

belongs_to :user
belongs_to :other_user, :class_name => “User”

Where is the has_many or has_one at the other end of this?

Colin