Rails 4 - checkboxes for has_and_belongs_to_many association

Question

I recently had a problem getting checkboxes to work for a has_and_belongs_to_many (HABTM) association in Rails 4. I was able to find the information on how to get it working

Answer 1

I implement has_and_belongs_to_many association this way:

model/role

class Role < ActiveRecord::Base
  has_and_belongs_to_many :users
end

model/user

class User < ActiveRecord::Base
  has_and_belongs_to_many :roles
end

users/_form.html.erb

---
----
-----
 

        <% for role in Role.all %>
            

                <%= check_box_tag "user[role_ids][]", role.id, @user.roles.include?(role) %>
                <%= role.name %>
            
        <% end %>
    

users_controller.rb

def user_params
    params.require(:user).permit(:name, :email, { role_ids:[] })
  end

Intermediate table_name should be roles_users and there should be two fields:

1. role_id
2. user_id