Fix preloading of has_one :through associations on belongs_to [#1507 …

…state:resolved]

Signed-off-by: Frederick Cheung <frederick.cheung@gmail.com>

activerecord/lib/active_record/association_preload.rb

@@ -204,9 +204,18 @@ def preload_has_one_association(records, reflection, preload_options={})
           unless through_records.empty?
             source = reflection.source_reflection.name
             through_records.first.class.preload_associations(through_records, source)
-            through_records.each do |through_record|
-              add_preloaded_record_to_collection(id_to_record_map[through_record[through_primary_key].to_s],
-                                                 reflection.name, through_record.send(source))
+            if through_reflection.macro == :belongs_to
+              rev_id_to_record_map, rev_ids = construct_id_map(records, through_primary_key)
+              rev_primary_key = through_reflection.klass.primary_key
+              through_records.each do |through_record|
+                add_preloaded_record_to_collection(rev_id_to_record_map[through_record[rev_primary_key].to_s],
+                                                   reflection.name, through_record.send(source))
+              end
+            else
+              through_records.each do |through_record|
+                add_preloaded_record_to_collection(id_to_record_map[through_record[through_primary_key].to_s],
+                                                   reflection.name, through_record.send(source))
+              end
             end
           end
         else

activerecord/lib/active_record/associations/association_collection.rb

@@ -83,7 +83,11 @@ def last(*args)
 
       def to_ary
         load_target
-        @target.to_ary
+        if @target.is_a?(Array)
+          @target.to_ary
+        else
+          Array(@target)
+        end
       end
 
       def reset

activerecord/test/cases/associations/has_one_through_associations_test.rb

@@ -1,13 +1,14 @@
 require "cases/helper"
 require 'models/club'
+require 'models/member_type'
 require 'models/member'
 require 'models/membership'
 require 'models/sponsor'
 require 'models/organization'
 require 'models/member_detail'
 
 class HasOneThroughAssociationsTest < ActiveRecord::TestCase
-  fixtures :members, :clubs, :memberships, :sponsors, :organizations
+  fixtures :member_types, :members, :clubs, :memberships, :sponsors, :organizations
 
   def setup
     @member = members(:groucho)
@@ -158,4 +159,18 @@ def test_reassigning_has_one_through
     assert @new_organization.members.include?(@member)
   end
 
+  def test_preloading_has_one_through_on_belongs_to
+    assert_not_nil @member.member_type
+    @organization = organizations(:nsa)
+    @member_detail = MemberDetail.new
+    @member.member_detail = @member_detail
+    @member.organization = @organization
+    @member_details = assert_queries(3) do
+      MemberDetail.find(:all, :include => :member_type)
+    end
+    @new_detail = @member_details[0]
+    assert @new_detail.loaded_member_type?
+    assert_not_nil assert_no_queries { @new_detail.member_type }
+  end
+
 end

activerecord/test/fixtures/member_types.yml

@@ -0,0 +1,6 @@
+founding:
+  id: 1
+  name: Founding
+provisional:
+  id: 2
+  name: Provisional

activerecord/test/fixtures/members.yml

@@ -1,4 +1,6 @@
 groucho:
   name: Groucho Marx
+  member_type_id: 1
 some_other_guy:
-  name: Englebert Humperdink
+  name: Englebert Humperdink
+  member_type_id: 2

activerecord/test/models/member.rb

@@ -8,4 +8,5 @@ class Member < ActiveRecord::Base
   has_one :sponsor_club, :through => :sponsor
   has_one :member_detail
   has_one :organization, :through => :member_detail
+  belongs_to :member_type
 end

activerecord/test/models/member_detail.rb

@@ -1,4 +1,5 @@
 class MemberDetail < ActiveRecord::Base
   belongs_to :member
   belongs_to :organization
+  has_one :member_type, :through => :member
 end

activerecord/test/models/member_type.rb

@@ -0,0 +1,3 @@
+class MemberType < ActiveRecord::Base
+  has_many :members
+end

activerecord/test/schema/schema.rb

@@ -195,6 +195,7 @@ def create_table(*args, &block)
 
   create_table :members, :force => true do |t|
     t.string :name
+    t.integer :member_type_id
   end
 
   create_table :member_details, :force => true do |t|
@@ -210,6 +211,10 @@ def create_table(*args, &block)
     t.string :type
   end
 
+  create_table :member_types, :force => true do |t|
+    t.string :name
+  end
+
   create_table :references, :force => true do |t|
     t.integer :person_id
     t.integer :job_id