7 files changed, 36 insertions, 37 deletions
diff --git a/lib/active_relation/primitives/attribute.rb b/lib/active_relation/primitives/attribute.rb
index d37271490a..5b1ef4d7c0 100644
--- a/lib/active_relation/primitives/attribute.rb
+++ b/lib/active_relation/primitives/attribute.rb
@@ -10,6 +10,10 @@ module ActiveRelation
     def alias_or_name
       @alias || name
     end
+    
+    def aggregation?
+      false
+    end
 
     module Transformations
       def as(aliaz = nil)
@@ -56,10 +60,8 @@ module ActiveRelation
       end
       
       def %(other)
-        if other
-          (history - other.history) + (other.history - history)
-        else
-          history
+        if other then (history - other.history) + (other.history - history)
+        else history
         end
       end
     end
diff --git a/lib/active_relation/primitives/expression.rb b/lib/active_relation/primitives/expression.rb
index 2df2888ba0..ae4c61d1b1 100644
--- a/lib/active_relation/primitives/expression.rb
+++ b/lib/active_relation/primitives/expression.rb
@@ -29,6 +29,10 @@ module ActiveRelation
       "#{function_sql}(#{attribute.to_sql})" + (@alias ? " AS #{quote_column_name(@alias)}" : '')
     end
     
+    def aggregation?
+      true
+    end
+    
     def ==(other)
       self.class    == other.class          and
       attribute     == other.attribute      and
diff --git a/lib/active_relation/relations.rb b/lib/active_relation/relations.rb
index 9cede2a6d1..d8e211c853 100644
--- a/lib/active_relation/relations.rb
+++ b/lib/active_relation/relations.rb
@@ -4,7 +4,7 @@ require 'active_relation/relations/compound'
 require 'active_relation/relations/writing'
 require 'active_relation/relations/table'
 require 'active_relation/relations/join'
-require 'active_relation/relations/aggregation'
+require 'active_relation/relations/grouping'
 require 'active_relation/relations/projection'
 require 'active_relation/relations/selection'
 require 'active_relation/relations/order'
diff --git a/lib/active_relation/relations/aggregation.rb b/lib/active_relation/relations/aggregation.rb
deleted file mode 100644
index 62432408e1..0000000000
--- a/lib/active_relation/relations/aggregation.rb
+++ /dev/null
@@ -1,24 +0,0 @@
-module ActiveRelation
-  class Aggregation < Compound
-    attr_reader :expressions, :groupings
-
-    def initialize(relation, options)
-      @relation, @expressions, @groupings = relation, options[:expressions], options[:groupings]
-    end
-
-    def ==(other)
-      self.class  == other.class      and
-      relation    == other.relation   and
-      groupings   == other.groupings  and
-      expressions == other.expressions
-    end
-
-    def attributes
-      expressions.collect { |e| e.bind(self) }
-    end
-    
-    def aggregation?
-      true
-    end
-  end
-end
-\ No newline at end of file
diff --git a/lib/active_relation/relations/grouping.rb b/lib/active_relation/relations/grouping.rb
new file mode 100644
index 0000000000..57323e90f3
--- /dev/null
+++ b/lib/active_relation/relations/grouping.rb
@@ -0,0 +1,19 @@
+module ActiveRelation
+  class Grouping < Compound
+    attr_reader :expressions, :groupings
+
+    def initialize(relation, *groupings)
+      @relation, @groupings = relation, groupings.collect { |g| g.bind(relation) }
+    end
+
+    def ==(other)
+      self.class  == other.class      and
+      relation    == other.relation   and
+      groupings   == other.groupings
+    end
+
+    def aggregation?
+      true
+    end
+  end
+end
+\ No newline at end of file
diff --git a/lib/active_relation/relations/projection.rb b/lib/active_relation/relations/projection.rb
index c1495c1742..0f8ea5175c 100644
--- a/lib/active_relation/relations/projection.rb
+++ b/lib/active_relation/relations/projection.rb
@@ -15,5 +15,9 @@ module ActiveRelation
       relation    == other.relation and
       projections == other.projections
     end
+    
+    def aggregation?
+      attributes.any?(&:aggregation?)
+    end
   end
 end
 \ No newline at end of file
diff --git a/lib/active_relation/relations/relation.rb b/lib/active_relation/relations/relation.rb
index b62a5d9fb9..8ab266c53d 100644
--- a/lib/active_relation/relations/relation.rb
+++ b/lib/active_relation/relations/relation.rb
@@ -66,8 +66,8 @@ module ActiveRelation
         skipped.blank?? self : Skip.new(self, skipped)
       end
   
-      def aggregate(*expressions)
-        AggregateOperation.new(self, expressions)
+      def group(*groupings)
+        groupings.all?(&:blank?) ? self : Grouping.new(self, *groupings)
       end
       
       module Writes
@@ -90,12 +90,6 @@ module ActiveRelation
           Join.new(join_sql, relation1, relation2, *predicates)
         end
       end
-      
-      AggregateOperation = Struct.new(:relation, :expressions) do
-        def group(*groupings)
-          Aggregation.new(relation, :expressions => expressions, :groupings => groupings)
-        end
-      end
     end
     include Operations