Rails - Oct 2007 - how do you access the :through join model objects?

Hello,

I have some confusion regarding how access the join model object that is
responsible for a relationship I am working with. Here''s a simple case:

class A < ActiveRecord::Base
  has_many :connections
  has_many :bs, :through => :connections
end


class B < ActiveRecord::Base
  has_many :connections
  has_many :as, :through => :connections
end

class Connection < ActiveRecord::Base
        belongs_to :a
        belongs_to :b
end

Now say I''ve already got my hands on an A, called a, and one of
it''s
b''s. So, I can already say a.bs[b_index].attribute = value.
That''s
great. But where is the Connection object that is tying this a to this
particular b? The object must exist. Let''s say I have a reference to it
called c, so that I can say c.attribute = value. But how do I get that
reference?

The only way I can see to do it is to find it manually via it''s own
class''s relationship, as in a.connections.find_by_b_id(b.id). But that
seems very WET (i.e. not DRY) to me; I shouldn''t have to do a search
for
an object, that I''m essentially already using.

FWIW, I''ve been searching on this forever, so I apologize if the answer
is out there & I''ve simply failed to find it.

TIA,
Avram
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a quick additional comment:

I would have thought I could say a.bs[i].connections and get *just* an 
array of the connection objects that tie b[i] to a. But instead it seems 
that I get all of bs[i]''s connections, whether or not they connect b to
a. I would think there would be a simple way to refer to just the 
objects that join a specific b to a specific a, without having to 
explicitly search for them. Is there?
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Avram Dorfman wrote:
> I have some confusion regarding how access the join model object that is
> responsible for a relationship I am working with. Here''s a simple
case:
> 
> class A < ActiveRecord::Base
>   has_many :connections
>   has_many :bs, :through => :connections
> end
> 
> 
> class B < ActiveRecord::Base
>   has_many :connections
>   has_many :as, :through => :connections
> end
> 
> class Connection < ActiveRecord::Base
>         belongs_to :a
>         belongs_to :b
> end
> 
> Now say I''ve already got my hands on an A, called a, and one of
it''s
> b''s. So, I can already say a.bs[b_index].attribute = value.
That''s
> great. But where is the Connection object that is tying this a to this
> particular b? The object must exist. Let''s say I have a reference
to it
> called c, so that I can say c.attribute = value. But how do I get that
> reference?
> 
> The only way I can see to do it is to find it manually via it''s
own
> class''s relationship, as in a.connections.find_by_b_id(b.id). But
that
> seems very WET (i.e. not DRY) to me; I shouldn''t have to do a
search for
> an object, that I''m essentially already using.
Usual way is:

a = A.find(:first, :conditions => ''...'', :include =>
{:connections => :b})

a.connections[b_index].attribute = value
a.connections[b_index].b.attribute = value


-- 
We develop, watch us RoR, in numbers too big to ignore.


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