Ticket #9711: has_many_through_uniq_calculations.patch

a/activerecord/lib/active_record/associations/has_many_through_association.rb

@@ -103 +103 @@
-        loaded? ? @target.size : count
-      end
-
+      # Makes the calculation automatically distinct if the association
+      # is uniq.
+      def calculate(operation, *args, &block)
+        options = args.extract_options!
+
+        if @reflection.options[:uniq] && !options.has_key?(:distinct)
+          options[:distinct] = true
+        end
+
+        args << options
+        super(operation, *args, &block)
+      end
+
+      # Calculate average using SQL, not Enumerable
+      def average(*args, &block)
+        calculate(:avg, *args, &block)
+      end
+
-      # Calculate sum using SQL, not Enumerable
-      def sum(*args, &block)
-        calculate(:sum, *args, &block)

a/activerecord/test/associations_test.rb

@@ -402 +402 @@
-
-class HasManyAssociationsTest < Test::Unit::TestCase
-  fixtures :accounts, :companies, :developers, :projects,
-
+
+
-
-  def setup
-    Client.destroyed_client_ids.clear
@@ -1034 +1035 @@
-  def test_assign_ids_for_through
-    assert_raise(NoMethodError) { authors(:mary).comment_ids = [123] }
-  end
+
+  def test_sum_on_uniq_through_association_uses_distinct_automatically
+    # non-unique posts.author_id: [ 1, 1 ]
+    assert_equal 1, authors(:mary).unique_categorized_posts.sum('posts.author_id')
+    assert_equal 2, authors(:mary).unique_categorized_posts.sum('posts.author_id', :distinct => false)
+  end
+
+  def test_average_on_uniq_through_association_uses_distinct_automatically
+    # non-unique posts.id: [2, 2]
+    assert_equal 2, authors(:mary).unique_categorized_posts.average('posts.id')
+    Categorization.create!(
+      :author_id => authors(:mary).id,
+      :post_id => posts(:thinking).id,
+      :category_id => categories(:general).id)
+    Categorization.create!(
+      :author_id => authors(:mary).id,
+      :post_id => posts(:welcome).id,
+      :category_id => categories(:general).id)
+    # non-unique posts.id: [1, 2, 2, 2]
+    assert_equal 1.5, authors(:mary).unique_categorized_posts.average('posts.id')
+    assert_equal 1.75, authors(:mary).unique_categorized_posts.average('posts.id', :distinct => false)
+  end
-end
-
-class BelongsToAssociationsTest < Test::Unit::TestCase