Not work has_many :through association

In the view form of user

\- for user in User\.all
  = check\_box\_tag 'role\[user\_ids\]\[\]', user\.id, @role\.users\.include?

(user) =h user.name

When I create a new user, nothing happens, the array of user_ids is empty

Those checkboxes will result in params['role[user_ids]'] being set to an array of user ids - What does your controller code look like? If it's just a classic User.create params[:user] that clearly isn't being used at all

Fred

But that's not what your form (at least not in your initial post) is doing - it's setting the attribute :user_ids in params[:role] which you aren't using. Did you actually mean to create a checkbox user[role_ids] for each role ?

Fred

you are right, my mistake in the user form i have this

\- for role in Role\.all
  = check\_box\_tag "user\[role\_ids\]\[\]", role\.id, @user\.roles\.include?

(role) =h role.name

If you look at your development log file does it actually look like those parameters are being submitted as you expected ?

Fred