Rails - Apr 2006 - collection_select has_and_belongs_to_many update_attributes

I know there have been threads on this before but I was thinking
shouldn''t multiple collection_select automatically update habtm
relations when you update_attributes?

In order to get multiple collection_select to work I use:

collection_select(:user, :group_ids, Group.find(:all), :id,
:name,{},{:multiple=>'''',:name=>''group[id][]''})

In fact if I don''t set the :name field like this I get an error:

undefined method `each'' for #<Group:0x40ad2ee4>
/usr/lib/ruby/gems/1.8/gems/activerecord-1.13.2/lib/active_record/base.rb:1501:in
`method_missing''

which suggests that ActiveRecord is expecting to loop through this list
of groups. However with the :name field set as above the error goes
away, but the habtm relation doesn''t get updated.

Actually as I was writing this I just worked out and tested the
solution, what''s needed is the following:

collection_select(:user, :group_ids, Group.find(:all), :id,
:name,{},{:multiple=>'''',:name=>''user[group_ids][]''})

Now this is something that should go in the rails recipes book!

It would rock even harder if the created_on stuff held for the habtm
join table as well ...

I made a doc patch and submitted it:

http://dev.rubyonrails.org/ticket/4837

CHEERS> SAM