title: Rails model has_many , belongs_to relations
body: <p>I have 2 models</p>
  
  <pre><code> class User &lt; ActiveRecord::Base
     has_many :products
   end
  
  class Product &lt; ActiveRecord::Base
    belongs_to :user
  end
  </code></pre>
  
  <p>Do I need to add a column user_id to the Product table or does rails add it by default ?</p>