Support has_one through assocs as the source association

activerecord/lib/active_record/associations/through_association_scope.rb

@@ -53,7 +53,7 @@ def construct_select(custom_select = nil)
       end
 
       def construct_joins(custom_joins = nil)
-        # puts @reflection.through_reflection_chain.map(&:inspect)
+        # p @reflection.through_reflection_chain
 
         "#{construct_through_joins} #{@reflection.options[:joins]} #{custom_joins}"
       end
@@ -67,16 +67,27 @@ def construct_through_joins
 
           case
             when left.source_reflection.nil?
-              left_primary_key  = left.primary_key_name
-              right_primary_key = right.klass.primary_key
+              # TODO: Perhaps need to pay attention to left.options[:primary_key] and
+              # left.options[:foreign_key] in places here
 
-              if left.options[:as]
-                polymorphic_join = "AND %s.%s = %s" % [
-                  table_aliases[left], "#{left.options[:as]}_type",
-                  # TODO: Why right.klass.name? Rather than left.active_record.name?
-                  # TODO: Also should maybe use the base_class (see related code in JoinAssociation)
-                  @owner.class.quote_value(right.klass.name)
-                ]
+              case left.macro
+                when :belongs_to
+                  left_primary_key  = left.klass.primary_key
+                  right_primary_key = right.primary_key_name
+                when :has_many, :has_one
+                  left_primary_key  = left.primary_key_name
+                  right_primary_key = right.klass.primary_key
+
+                  if left.options[:as]
+                    polymorphic_join = "AND %s.%s = %s" % [
+                      table_aliases[left], "#{left.options[:as]}_type",
+                      # TODO: Why right.klass.name? Rather than left.active_record.name?
+                      # TODO: Also should maybe use the base_class (see related code in JoinAssociation)
+                      @owner.class.quote_value(right.klass.name)
+                    ]
+                  end
+                when :has_and_belongs_to_many
+                  raise NotImplementedError
               end
             when left.source_reflection.macro == :belongs_to
               left_primary_key  = left.klass.primary_key

activerecord/test/cases/associations/nested_has_many_through_associations_test.rb

@@ -18,6 +18,9 @@
 require 'models/book'
 require 'models/subscription'
 require 'models/rating'
+require 'models/member'
+require 'models/member_detail'
+require 'models/member_type'
 
 # NOTE: Some of these tests might not really test "nested" HMT associations, as opposed to ones which
 # are just one level deep. But it's all the same thing really, as the "nested" code is being 
@@ -26,7 +29,8 @@
 
 class NestedHasManyThroughAssociationsTest < ActiveRecord::TestCase
   fixtures :authors, :books, :posts, :subscriptions, :subscribers, :tags, :taggings,
-           :people, :readers, :references, :jobs, :ratings, :comments
+           :people, :readers, :references, :jobs, :ratings, :comments, :members, :member_details,
+           :member_types
 
   # Through associations can either use the has_many or has_one macros.
   # 
@@ -56,6 +60,9 @@ def test_has_many_through_a_has_many_through_association_on_source_reflection
     authors = Author.joins(:tags).where('tags.id' => tags(:general).id)
     assert_equal [authors(:david)], authors.uniq
 
+    authors = Author.includes(:tags)
+    assert_equal [tags(:general), tags(:general)], authors.first.tags
+
     # This ensures that the polymorphism of taggings is being observed correctly
     authors = Author.joins(:tags).where('taggings.taggable_type' => 'FakeModel')
     assert authors.empty?
@@ -71,11 +78,24 @@ def test_has_many_through_a_has_many_through_association_on_through_reflection
     # All authors with subscribers where one of the subscribers' nick is 'alterself'
     authors = Author.joins(:subscribers).where('subscribers.nick' => 'alterself')
     assert_equal [authors(:david)], authors
+
+    # TODO: Make this work
+    # authors = Author.includes(:subscribers)
+    # assert_equal [subscribers(:first), subscribers(:second), subscribers(:second)], authors.first.subscribers
   end
 
-  # TODO: has_many through
+  # has_many through
   # Source: has_one through
   # Through: has_one
+  def test_has_many_through_has_one_with_has_one_through_source_reflection
+    assert_equal [member_types(:founding)], members(:groucho).nested_member_types
+
+    members = Member.joins(:nested_member_types).where('member_types.id' => member_types(:founding).id)
+    assert_equal [members(:groucho)], members
+
+    members = Member.includes(:nested_member_types)
+    assert_equal [member_types(:founding)], members.first.nested_member_types
+  end
 
   # TODO: has_many through
   # Source: has_one
@@ -105,9 +125,18 @@ def test_has_many_through_a_has_many_through_association_on_through_reflection
   # Source: has_many through
   # Through: belongs_to
 
-  # TODO: has_one through
+  # has_one through
   # Source: has_one through
   # Through: has_one
+  def test_has_one_through_has_one_with_has_one_through_source_reflection
+    assert_equal member_types(:founding), members(:groucho).nested_member_type
+
+    members = Member.joins(:nested_member_type).where('member_types.id' => member_types(:founding).id)
+    assert_equal [members(:groucho)], members
+
+    members = Member.includes(:nested_member_type)
+    assert_equal member_types(:founding), members.first.nested_member_type
+  end
 
   # TODO: has_one through
   # Source: belongs_to

activerecord/test/fixtures/member_details.yml

@@ -0,0 +1,3 @@
+groucho:
+  id: 1
+  member_id: 1

activerecord/test/fixtures/members.yml

@@ -1,6 +1,8 @@
 groucho:
+  id: 1
   name: Groucho Marx
   member_type_id: 1
 some_other_guy:
+  id: 2
   name: Englebert Humperdink
   member_type_id: 2

activerecord/test/fixtures/memberships.yml

@@ -1,20 +1,20 @@
 membership_of_boring_club:
   joined_on: <%= 3.weeks.ago.to_s(:db) %>
   club: boring_club
-  member: groucho
+  member_id: 1
   favourite: false
   type: CurrentMembership
 
 membership_of_favourite_club:
   joined_on: <%= 3.weeks.ago.to_s(:db) %>
   club: moustache_club
-  member: groucho
+  member_id: 1
   favourite: true
   type: Membership
 
 other_guys_membership:
   joined_on: <%= 4.weeks.ago.to_s(:db) %>
   club: boring_club
-  member: some_other_guy
+  member_id: 2
   favourite: false
   type: CurrentMembership

activerecord/test/fixtures/sponsors.yml

@@ -1,9 +1,12 @@
 moustache_club_sponsor_for_groucho:
   sponsor_club: moustache_club
-  sponsorable: groucho (Member)
+  sponsorable_id: 1
+  sponsorable_type: Member
 boring_club_sponsor_for_groucho:
   sponsor_club: boring_club
-  sponsorable: some_other_guy (Member)
+  sponsorable_id: 2
+  sponsorable_type: Member
 crazy_club_sponsor_for_groucho:
   sponsor_club: crazy_club
-  sponsorable: some_other_guy (Member)
+  sponsorable_id: 2
+  sponsorable_type: Member

activerecord/test/models/member.rb

@@ -9,4 +9,7 @@ class Member < ActiveRecord::Base
   has_one :member_detail
   has_one :organization, :through => :member_detail
   belongs_to :member_type
-end
+
+  has_many :nested_member_types, :through => :member_detail, :source => :member_type
+  has_one :nested_member_type, :through => :member_detail, :source => :member_type
+end