group nodes are working!

6 files changed, 58 insertions, 4 deletions

diff --git a/lib/arel/nodes.rb b/lib/arel/nodes.rb
index 6dcd86867a..bf7ae830d0 100644
--- a/lib/arel/nodes.rb
+++ b/lib/arel/nodes.rb
@@ -14,6 +14,7 @@ require 'arel/nodes/delete_statement'
 require 'arel/nodes/unqualified_column'
 require 'arel/nodes/table_alias'
 require 'arel/nodes/join'
+require 'arel/nodes/group'
 require 'arel/nodes/inner_join'
 require 'arel/nodes/outer_join'
 require 'arel/nodes/string_join'
diff --git a/lib/arel/nodes/group.rb b/lib/arel/nodes/group.rb
new file mode 100644
index 0000000000..57a7c579da
--- /dev/null
+++ b/lib/arel/nodes/group.rb
@@ -0,0 +1,11 @@
+module Arel
+  module Nodes
+    class Group
+      attr_accessor :expr
+
+      def initialize expr
+        @expr = expr
+      end
+    end
+  end
+end
diff --git a/lib/arel/nodes/select_core.rb b/lib/arel/nodes/select_core.rb
index 5e27c7c414..6e85968b31 100644
--- a/lib/arel/nodes/select_core.rb
+++ b/lib/arel/nodes/select_core.rb
@@ -1,19 +1,21 @@
 module Arel
   module Nodes
     class SelectCore
-      attr_reader :froms, :projections, :wheres
+      attr_reader :froms, :projections, :wheres, :groups
 
       def initialize
         @froms       = []
         @projections = []
         @wheres      = []
+        @groups      = []
       end
 
       def initialize_copy other
         super
-        @froms = @froms.clone
+        @froms       = @froms.clone
         @projections = @projections.clone
-        @wheres = @wheres.clone
+        @wheres      = @wheres.clone
+        @group       = @groups.clone
       end
     end
   end
diff --git a/lib/arel/select_manager.rb b/lib/arel/select_manager.rb
index c9214b20a2..3ac6a5cbc8 100644
--- a/lib/arel/select_manager.rb
+++ b/lib/arel/select_manager.rb
@@ -13,6 +13,13 @@ module Arel
       self
     end
 
+    def group *columns
+      columns.each do |column|
+        @ctx.groups.push Nodes::Group.new column
+      end
+      self
+    end
+
     def from table
       @ctx.froms << table
       self
diff --git a/lib/arel/visitors/to_sql.rb b/lib/arel/visitors/to_sql.rb
index 4ac38fb13e..55b3259e81 100644
--- a/lib/arel/visitors/to_sql.rb
+++ b/lib/arel/visitors/to_sql.rb
@@ -54,10 +54,15 @@ module Arel
         [
           "SELECT #{o.projections.map { |x| visit x }.join ', '}",
           ("FROM #{o.froms.map { |x| visit x }.join ', ' }" unless o.froms.empty?),
-          ("WHERE #{o.wheres.map { |x| visit x }.join ' AND ' }" unless o.wheres.empty?)
+          ("WHERE #{o.wheres.map { |x| visit x }.join ' AND ' }" unless o.wheres.empty?),
+          ("GROUP BY #{o.groups.map { |x| visit x }.join ', ' }" unless o.groups.empty?)
         ].compact.join ' '
       end
 
+      def visit_Arel_Nodes_Group o
+        visit o.expr
+      end
+
       def visit_Arel_Nodes_Count o
         "COUNT(#{o.distinct ? 'DISTINCT ' : ''}#{o.expressions.map { |x| visit x }.join(', ')})"
       end
diff --git a/spec/arel/select_manager_spec.rb b/spec/arel/select_manager_spec.rb
index 775a0e6162..a6f5765b44 100644
--- a/spec/arel/select_manager_spec.rb
+++ b/spec/arel/select_manager_spec.rb
@@ -128,6 +128,34 @@ module Arel
       end
     end
 
+    describe 'group' do
+      it 'takes an attribute' do
+        table   = Table.new :users
+        manager = Arel::SelectManager.new Table.engine
+        manager.from table
+        manager.group table[:id]
+        manager.to_sql.should be_like %{
+          SELECT FROM "users" GROUP BY "users"."id"
+        }
+      end
+
+      it 'chains' do
+        table   = Table.new :users
+        manager = Arel::SelectManager.new Table.engine
+        check manager.group(table[:id]).should == manager
+      end
+
+      it 'takes multiple args' do
+        table   = Table.new :users
+        manager = Arel::SelectManager.new Table.engine
+        manager.from table
+        manager.group table[:id], table[:name]
+        manager.to_sql.should be_like %{
+          SELECT FROM "users" GROUP BY "users"."id", "users"."name"
+        }
+      end
+    end
+
     describe 'delete' do
       it "copies from" do
         engine  = EngineProxy.new Table.engine