Belongs_to :through

Rails
1

hi there,
lets say you have: A that belongs_to :b, and B belongs_to :c

how do you normally go about saying A belongs_to :c, :through => :b ??

searching I found two solutions:

  1. method:
    class A
    def c
    b.c
    end
    end

and

2.delegate:
class A
delegate :c, :to => :b
end

but neither will have the benefits of generated sql with joins.

How you normally do this? and What are the reasons against having it on
rails itself?

greetings
joaquin

–

2

Joaquin Rivera padron wrote:

hi there,
lets say you have: A that belongs_to :b, and B belongs_to :c

how do you normally go about saying A belongs_to :c, :through => :b ??

If A belongs_to :b, that means that Rails expects a b_id field in A’s
table. In your case, that doesn’t exist, so what you want is
A has_one :c, :through => :b

Best,

Marnen Laibow-Koser
http://www.marnen.org
[email protected]

3

Marnen Laibow-Koser wrote:

Joaquin Rivera padron wrote:

hi there,
lets say you have: A that belongs_to :b, and B belongs_to :c

how do you normally go about saying A belongs_to :c, :through => :b ??

If A belongs_to :b, that means that Rails expects a b_id field in A’s
table. In your case, that doesn’t exist, so what you want is
A has_one :c, :through => :b

Wow, that was stupid of me. I must not have been awake when I wrote
that. has_one :through will probably work, but my explanation is
totally inaccurate. Sorry.

Best,

Marnen Laibow-Koser
http://www.marnen.org
[email protected]