belongs_to :through

rubyonrails-talk
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,

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.