Rails - Jul 2009 - has_many :through habtm

Here is my setup:

class Product < ActiveRecord::Base
  belongs_to :catalog
  has_and_belongs_to_many :product_groups
end

class ProductGroup < ActiveRecord::Base
  belongs_to :catalog
  has_and_belongs_to_many :products
end

class Catalog < ActiveRecord::Base
  has_many :product_groups
  has_many :products, :through => :product_groups
end

I get:
Invalid source reflection macro :has_and_belongs_to_many for
has_many :products, :through => :product_groups.  Use :source to
specify the source reflection.

----------
I have seen a few threads with posts asking this question, but found
no suitable solution or workaround..
any ideas please.

As written, there''s no direct way to do this association in Rails. But
wouldn''t it be sufficient to use a plain has_many :products in
Catalog? You''ve got a corresponding belongs_to in Product...

--Matt Jones

On Jul 9, 6:42 pm, slava
<mikerin.sl...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> Here is my setup:
>
> class Product < ActiveRecord::Base
>   belongs_to :catalog
>   has_and_belongs_to_many :product_groups
> end
>
> class ProductGroup < ActiveRecord::Base
>   belongs_to :catalog
>   has_and_belongs_to_many :products
> end
>
> class Catalog < ActiveRecord::Base
>   has_many :product_groups
>   has_many :products, :through => :product_groups
> end
>
> I get:
> Invalid source reflection macro :has_and_belongs_to_many for
> has_many :products, :through => :product_groups.  Use :source to
> specify the source reflection.
>
> ----------
> I have seen a few threads with posts asking this question, but found
> no suitable solution or workaround..
> any ideas please.

yeah, I think it is sufficient. thanks.