In the parent class place the following code has_many :posts, :dependent => :destroy This used to be accomplished with has_many :posts, :dependent=>true Check out the Rails docs for more information http://api.rubyonrails.org/classes/ActiveRecord/As...

How to validate uniqueness in a :has_many :through relationship with Ruby on Rails. You'll need three models in this example List, Subscriber and ListSubscriber. A list has many subscribers and a subscriber has many lists. Simple enough. Running the follo...