cancan & many_to_many associations

I'm trying to write a rule for man开发者_运维知识库y_to_many association. Because of the association table some results are duplicated.

The code in my ability is: I have many Users that have many Groups and i want to show all Post that their author belongs to a group the same as the current_user's group. can :read, Post, :user => { :group => { :id => user.groups.collect { |g| g.id } } }

I took the generated SQL from the log and ran it in MySql query builder. The duplications appear at the SQL level.

How can i get rid of the duplicated results ?!

UPDATE 1:

The generated SQL: SELECT posts.* FROM posts INNER JOIN users ON users.id = posts.user_id INNER JOIN groups_users ON groups_users.user_id = users.id INNER JOIN groups ON groups.id = groups_users.group_id WHERE (groups.id IN (1, 2)) LIMIT 30 OFFSET 0

i updated my post to include the generated SQL. the problem is that if a user belongs to 2 groups than i get duplicated results. isn't there a way to "distinct" the results ?

You could try using the uniq Array method after you've returned the group IDs.

Instead of:

can :read, Post, :user => { :group => { :id => user.groups.collect { |g| g.id } } }

Try:

can :read, Post, :user => {:group => { :id => user.groups.map(&:id).uniq } }

I decided to use a named scope in order to get DISTINCT results for my query.

I added this to post.rb: named_scope :unique_posts, :select => "DISTINCT 'posts'.*"

Now i get distinct results when i call @posts.unique_posts