2 files changed, 119 insertions, 1 deletions
diff --git a/activerecord/lib/active_record/association_preload.rb b/activerecord/lib/active_record/association_preload.rb
index 9ef8ed15e8..313c51dae0 100644
--- a/activerecord/lib/active_record/association_preload.rb
+++ b/activerecord/lib/active_record/association_preload.rb
@@ -34,7 +34,11 @@ module ActiveRecord
         reflection = reflections[association]
         raise ConfigurationError, "Association named '#{ association }' was not found; perhaps you misspelled it?" unless reflection
 
-        send(:"preload_#{reflection.macro}_association", records, reflection, preload_options)
+        # Not all records have the same class, so group then preload.
+        records.group_by(&:class).each do |klass, records|
+          reflection = klass.reflections[association]
+          send("preload_#{reflection.macro}_association", records, reflection, preload_options)
+        end
       end
 
       def add_preloaded_records_to_collection(parent_records, reflection_name, associated_record)
diff --git a/activerecord/test/cases/associations/eager_load_nested_include_test.rb b/activerecord/test/cases/associations/eager_load_nested_include_test.rb
new file mode 100644
index 0000000000..106f0691b6
--- /dev/null
+++ b/activerecord/test/cases/associations/eager_load_nested_include_test.rb
@@ -0,0 +1,114 @@
+require 'cases/helper'
+
+class EagerLoadPolyAssocsTest < Test::Unit::TestCase
+  NUM_SIMPLE_OBJS = 50
+  NUM_SHAPE_EXPRESSIONS = 100
+
+  def setup
+    silence_stream(STDOUT) { create_test_tables }
+    generate_test_object_graphs
+  end
+
+  def create_test_tables
+    conn = ActiveRecord::Base.connection
+    options = { :force => true, :options => "Engine=MyISAM" }
+
+    [:circles, :squares, :triangles, :non_poly_ones, :non_poly_twos].each do |t|
+      conn.create_table(t, options) { }
+    end
+
+    conn.create_table :shape_expressions, options do |t|
+      t.string  :paint_type
+      t.integer :paint_id
+      t.string  :shape_type
+      t.integer :shape_id
+    end
+    conn.create_table :paint_colors, options do |t|
+      t.integer :non_poly_one_id
+    end
+    conn.create_table :paint_textures, options do |t|
+      t.integer :non_poly_two_id
+    end
+  end
+
+  def teardown
+    drop_tables
+  end
+
+  def drop_tables
+    conn = ActiveRecord::Base.connection
+    conn.reconnect!
+
+    silence_stream(STDOUT) do
+      [:circles, :squares, :triangles, :paint_colors, :paint_textures,
+       :shape_expressions, :non_poly_ones, :non_poly_twos].each do |t|
+        conn.drop_table t
+      end
+    end
+  end
+
+  # meant to be supplied as an ID, never returns 0
+  def rand_simple
+    val = (NUM_SIMPLE_OBJS * rand).round
+    val == 0 ? 1 : val
+  end
+
+  def generate_test_object_graphs
+    1.upto(NUM_SIMPLE_OBJS) do
+      [Circle, Square, Triangle, NonPolyOne, NonPolyTwo].map(&:create!)
+    end
+    1.upto(NUM_SIMPLE_OBJS) do |i|
+      PaintColor.create!(:non_poly_one_id => rand_simple)
+      PaintTexture.create!(:non_poly_two_id => rand_simple)
+    end
+    1.upto(NUM_SHAPE_EXPRESSIONS) do |i|
+      ShapeExpression.create!(:shape_type => [Circle, Square, Triangle].rand.to_s, :shape_id => rand_simple,
+                              :paint_type => [PaintColor, PaintTexture].rand.to_s, :paint_id => rand_simple)
+    end
+  end
+
+  def test_include_query
+    res = 0
+    res = ShapeExpression.find :all, :include => [ :shape, { :paint => :non_poly } ]
+    assert_equal NUM_SHAPE_EXPRESSIONS, res.size
+    ShapeExpression.connection.disconnect!
+    assert_nothing_raised "confirm we can access associations in memory" do
+      res.each do |se|
+        assert_not_nil se.paint.non_poly, "this is the association that was loading incorrectly before the change"
+        assert_not_nil se.shape, "just making sure other associations still work"
+      end
+    end
+    assert_raise ActiveRecord::StatementInvalid, "An exception should be raised when db connectivity is required" do
+      res[0].reload
+    end
+  end
+end
+
+class ShapeExpression < ActiveRecord::Base
+  belongs_to :shape, :polymorphic => true
+  belongs_to :paint, :polymorphic => true
+end
+
+class Circle < ActiveRecord::Base
+  has_many :shape_expressions, :as => :shape
+end
+class Square < ActiveRecord::Base
+  has_many :shape_expressions, :as => :shape
+end
+class Triangle < ActiveRecord::Base
+  has_many :shape_expressions, :as => :shape
+end
+class PaintColor  < ActiveRecord::Base
+  has_many   :shape_expressions, :as => :paint
+  belongs_to :non_poly, :foreign_key => "non_poly_one_id", :class_name => "NonPolyOne"
+end
+class PaintTexture < ActiveRecord::Base
+  has_many   :shape_expressions, :as => :paint
+  belongs_to :non_poly, :foreign_key => "non_poly_two_id", :class_name => "NonPolyTwo"
+end
+class NonPolyOne < ActiveRecord::Base
+  has_many :paint_colors
+end
+class NonPolyTwo < ActiveRecord::Base
+  has_many :paint_textures
+end