Add Relation#except

activerecord/CHANGELOG

@@ -1,5 +1,10 @@
 *Edge*
 
+* Add Relation#except. [Pratik Naik]
+
+  one_red_item = Item.where(:colour => 'red').limit(1)
+  all_items = one_red_item.except(:where, :limit)
+
 * Add Relation#delete_all. [Pratik Naik]
 
   Item.where(:colour => 'red').delete_all

activerecord/lib/active_record/relation/spawn_methods.rb

@@ -45,5 +45,27 @@ def merge(r)
 
     alias :& :merge
 
+    def except(*skips)
+      result = Relation.new(@klass, table)
+      result.table = table
+
+      [:eager_load, :preload, :includes].each do |load_method|
+        result = result.send(load_method, send(:"#{load_method}_associations"))
+      end
+
+      result.readonly = self.readonly unless skips.include?(:readonly)
+
+      result = result.joins(@relation.joins(@relation)) unless skips.include?(:joins)
+      result = result.group(@relation.groupings) unless skips.include?(:group)
+      result = result.limit(@relation.taken) unless skips.include?(:limit)
+      result = result.offset(@relation.skipped) unless skips.include?(:offset)
+      result = result.select(@relation.send(:select_clauses)) unless skips.include?(:select)
+      result = result.from(@relation.sources) unless skips.include?(:from)
+      result = result.order(order_clause) unless skips.include?(:order)
+      result = result.where(*@relation.wheres) unless skips.include?(:where)
+
+      result
+    end
+
   end
 end

activerecord/test/cases/relations_test.rb

@@ -539,4 +539,16 @@ def test_create_bang
     assert ! hen.new_record?
     assert_equal 'hen', hen.name
   end
+
+  def test_except
+    relation = Post.where(:author_id => 1).order('id ASC').limit(1)
+    assert_equal [posts(:welcome)], relation.all
+
+    author_posts = relation.except(:order, :limit)
+    assert_equal Post.where(:author_id => 1).all, author_posts.all
+
+    all_posts = relation.except(:where, :order, :limit)
+    assert_equal Post.all, all_posts.all
+  end
+
 end