Rails find by *all* associated tags.id in

Question

Hi

Say I have a model Taggable has_many tags, how may I find all taggables by their associated tag's taggable_id field?

Taggable.find(:all, :joins => :tags, :conditions => {:tags => {:taggable_id => [1,2,3]}})

results in this:

SELECT `taggables`.* FROM `taggables` INNER JOIN `tags` ON tags.taggable_id = taggables.id WHERE (`tag`.`taggable_id` IN (1,2,3))

The syntax is incredible but does not fit my needs in that the resulting sql returns any taggable that has any, some or all of the tags.

How can I find taggables with related tags of field taggable_id valued 1, 2 and 3?

Thanks for any advice. :)

UPDATE:

I have found a solution which I'll post for others, should they end up here. Also though for the attention of others whose suggestions for improvement I'd happily receive. :)

Taggable.find(:all, :joins => :tags, :select => "taggables.*, tags.count tag_count", :conditions => {:tags => {:taggable_id => array_of_tag_ids}}, :group => "taggables.id having tag_count = #{array_of_tag_ids.count}"))

Answer 1

Your question is a bit confusing ('tags' seemed to be used quite a bit :)), but I think you want the same thing I needed here:

Taggable.find([1,2,3], :include => :tags).tags.map { |t| t.taggables }

or (if you want the results to be unique, which you probably do):

Taggable.find([1,2,3], :include => :tags).tags.map { |t| t.taggables }.flatten.uniq

This gets at all the taggables that have the same tags as the taggables that have ids 1,2, and 3. Is that what you wanted?