Ruby on Rails Association Extensions

Geschreven door: Tom-Eric

Imagine a user that has a inbox full of messages, now somewhere in your application, you want to get the number of unread messages. You could do a bit of sql, but isn’t this nicer?

class User < ActiveRecord::Base
  has_many :messages,
           :foreign_key => 'receiver_id' do
    def unread
      find :all, :conditions => ['viewed_at is null']
    end
  end
end

Now you can use User.find(:first).messages.unread to get the unread messages of the first user.

These kinds of methods are called Association Extensions and you can read more about them on the associations documentation page.

Gepubliceerd op donderdag, 26 oktober, 2006 onder Persoonlijk. Volg het commentaar op dit artikel via de RSS 2.0 feed. U kunt uw reactie achterlaten, of een trackback plaatsen vanaf uw eigen weblog.