Rails idiom to avoid duplicates in has_many :through

Question

I have a standard many-to-many relationship between users and roles in my Rails app:

class User < ActiveRecord::Base
  has_many :user_roles
  has_many :ro         


        

Answer 1

Perhaps it is possible to create the validation rule

validates_uniqueness_of :user_roles

then catch the validation exception and carry on gracefully. However, this feels really hacky and is very inelegant, if even possible.