Has a lot through the expansion of the association

Question

Is it possible for setting a to have a lot through an extension of the association? I have:

class User < ActiveRecord::Base has_many :friendships do def accepted where status: "accepted" end def rejected where status: "rejected" end end has_many :friends, through: :friendships do def accepted # Something equivalent to the following using association extension: # where("friendships.status = 'accepted'") end def rejected # Something equivalent to the following using association extension: # where("friendships.status = 'rejected'") end end end 

How to set up friends' communication (through friendships) by expanding the association of friends?

Answer 1

If you use Arel expressions for the where relation, you can untie these methods and reconnect them to the friends association:

 class User < ActiveRecord::Base has_many :friendships do def accepted where(Friendship.arel_table[:status].eq('accepted')) end def rejected where(Friendship.arel_table[:status].eq('rejected')) end end has_many :friends, through: :friendships do def accepted proxy_association.owner.friendships.extensions.first.instance_method(:accepted).bind(self).call end def rejected proxy_association.owner.friendships.extensions.first.instance_method(:rejected).bind(self).call end end end 

SQL will be generated correctly with this code, so this test will pass:

 def test_stuff tom = User.create! name: "tom" fred = Friend.create! name: "fred" jerry = Friend.create! name: "jerry" Friendship.create! user: tom, friend: fred, status: 'accepted' Friendship.create! user: tom, friend: jerry, status: 'rejected' tom.reload fred.reload assert_equal "fred", tom.friends.accepted.first.name assert_equal "jerry", tom.friends.rejected.first.name end 

Answer 2

The first thing that comes to my mind:

 class User < ActiveRecord::Base has_many :accepted_friendships, :class_name => "Friendship", :conditions => ... has_many :accepted_friends, through => :accepted_friendhips, :source => :friend end