Rails - May 2005 - Specifying :delete_sql on a has_and_belongs_to_many assocation

Hi all, I need specify a custom delete sql query for a
has_and_belongs_to_many association in one of my models.  The problem
is, there''s no reference that I can find that tells me what variables
I can use in the query.  Here''s what I have so far (simplified from
actual code):

class Issue < ActiveRecord::Base
  has_and_belongs_to_many :writers, :delete_sql => ''DELETE FROM
creators_issues WHERE issue_id = #{id} AND creator_id = 0''

I figured out I can access the model''s local methods.  But, how do I
get the ID of the record I''m removing from the habtm collection?

I''ve been digging through AR and the association classes but I keep
going around in circles.  Where''s a good place to start my path to
discovery of how AR works?
-- 
rick
http://techno-weenie.net

can''t you just use the clear method to remove all the associations
from the join table and add it into your destroy instead of bothering
with that? That appears to be what you are doing.
-- 
-Kate
(masukomi-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org)

On 5/14/05, Rick Olson
<technoweenie-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> Hi all, I need specify a custom delete sql query for a
> has_and_belongs_to_many association in one of my models.  The problem
> is, there''s no reference that I can find that tells me what
variables
> I can use in the query.  Here''s what I have so far (simplified
from
> actual code):
> 
> class Issue < ActiveRecord::Base
>   has_and_belongs_to_many :writers, :delete_sql => ''DELETE FROM
> creators_issues WHERE issue_id = #{id} AND creator_id = 0''
> 
> I figured out I can access the model''s local methods.  But, how do
I
> get the ID of the record I''m removing from the habtm collection?
> 
> I''ve been digging through AR and the association classes but I
keep
> going around in circles.  Where''s a good place to start my path to
> discovery of how AR works?
> --
> rick
> http://techno-weenie.net
> _______________________________________________
> Rails mailing list
> Rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>

On 5/14/05, kate rhodes <masukomi-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> can''t you just use the clear method to remove all the associations
> from the join table and add it into your destroy instead of bothering
> with that? That appears to be what you are doing.
That wasn''t a real example.  I used ''creator_id = 0''
because I didn''t
know what I could use there.

Anyways, I found the bug.  It''s patched now in Ticket #1299
(http://dev.rubyonrails.com/ticket/1299). I added a couple tests and
added an example to the docs for habtm.

-- 
rick
http://techno-weenie.net