Rails - Jan 2006 - Multiple HABTM relationships with self ???

I need to have a table related to itself via a join table. Will HABTM 
support this? That is:

class Recipe < ActiveRecord::Base
    has_and_belongs_to_many :recipes,  :join_table =>
"recipes_recipes"
end

More importantly -- how does RoR support MULTIPLE self-joins? I.e., to 
relate the table to itself via multiple join tables.

SFAIK, HABTM won''t support multiple self-joins because the method names
would get confused.

Could I create additional controllers for the class, and then use the 
:class_name option to specify those controllers?

SOrt of like so:

class Recipe < ActiveRecord::Base

    set_primary_key "R_ID"
    has_and_belongs_to_many :recipes,  :join_table =>
"recipes_recipes",
:foreign_key => "R_ID", :association_foreign_key =>
"R_ID2"
    has_and_belongs_to_many :recipes2,  :join_table => 
"recipes_recipes2", :foreign_key => "R_ID",
:association_foreign_key =>
"R_ID2"
    has_and_belongs_to_many :recipes3,  :join_table => 
"recipes_recipes3", :foreign_key => "R_ID",
:association_foreign_key =>
"R_ID2"

end


Thanks!

-- 
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Ok - I answered my first question.  HABTM works to relate a table to 
itself just fine.

Now how to do it again?  (And again!)

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2nd Q A''d 2. qed

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maybe this will help?

http://wiki.rubyonrails.com/rails/pages/HowToUseManyToManyAgainstASingleTable

Peter Michaux wrote:
> maybe this will help?
> 
>
http://wiki.rubyonrails.com/rails/pages/HowToUseManyToManyAgainstASingleTable
Geez, I had seen that article before, and was looking for it today, but 
for some reason I couldn''t locate it when I needed it (doh!). A bit 
late, as I already figured a way, but Thanks just same --

I think I ended up doing it somewhat differently - this article doesn''t
display everything so I can''t be sure. Since I''ve already
completed this
I didn''t replicate their approach so I''m not exactly sure
what''s missing
in this howto.

Anyway, all I did was create a new model for each relationship R1, R2, 
..., R5 against the same table R and then within each of these new 
models used set_table_name R and set_primary_id.  Then it was a simple 
matter to create a HABTM for each of these new self-referential joins in 
the model for R. Slick!  Same effect though, partially connected node 
graph.

BTW are the SQL statements behind HABTM reasonably optimized?  I''m
using
about 5 of these self-referential queries simultaneously against a 
moderately large database and it is taking about 5-10 seconds to return. 
I''m wondering what is the next step for either optimizing this query or
somehow caching results dynamically or perhaps pre-caching results in 
advance (hopefully without losing generality).

Thanks again --

-- 
Posted via http://www.ruby-forum.com/.

dr plutes wrote:
> BTW are the SQL statements behind HABTM reasonably optimized?  I''m
using
> about 5 of these self-referential queries simultaneously against a 
> moderately large database and it is taking about 5-10 seconds to return. 
> I''m wondering what is the next step for either optimizing this
query or
> somehow caching results dynamically or perhaps pre-caching results in 
> advance (hopefully without losing generality).
I doubt they''d be overly optimised beyond the basics - it''d
probably be
worth checking what turns up in the development log to see if you can 
see anything obviously wrong.

And, as always, check your indices :-)

-- 
Alex