Windowing support for PARTITION BY clause.

3 files changed, 21 insertions, 2 deletions

diff --git a/lib/arel/nodes/window.rb b/lib/arel/nodes/window.rb
index 60259e8c05..6578a414d2 100644
--- a/lib/arel/nodes/window.rb
+++ b/lib/arel/nodes/window.rb
@@ -1,10 +1,12 @@
 module Arel
   module Nodes
     class Window < Arel::Nodes::Node
-      attr_accessor :orders, :framing
+      attr_accessor :orders, :framing, :partitions
 
       def initialize
         @orders = []
+        @partitions = []
+        @framing = nil
       end
 
       def order *expr
@@ -15,6 +17,14 @@ module Arel
         self
       end
 
+      def partition *expr
+        # FIXME: We SHOULD NOT be converting these to SqlLiteral automatically
+        @partitions.concat expr.map { |x|
+          String === x || Symbol === x ? Nodes::SqlLiteral.new(x.to_s) : x
+        }
+        self
+      end
+
       def frame(expr)
         @framing = expr
       end
@@ -39,7 +49,8 @@ module Arel
       def eql? other
         self.class == other.class &&
           self.orders == other.orders &&
-          self.framing == other.framing
+          self.framing == other.framing &&
+          self.partitions == other.partitions
       end
       alias :== :eql?
     end
diff --git a/lib/arel/visitors/dot.rb b/lib/arel/visitors/dot.rb
index d96cf7a6a0..f0cefeabd7 100644
--- a/lib/arel/visitors/dot.rb
+++ b/lib/arel/visitors/dot.rb
@@ -82,12 +82,14 @@ module Arel
       alias :visit_Arel_Nodes_Range             :unary
 
       def window o
+        visit_edge o, "partitions"
         visit_edge o, "orders"
         visit_edge o, "framing"
       end
       alias :visit_Arel_Nodes_Window            :window
 
       def named_window o
+        visit_edge o, "partitions"
         visit_edge o, "orders"
         visit_edge o, "framing"
         visit_edge o, "name"
diff --git a/lib/arel/visitors/to_sql.rb b/lib/arel/visitors/to_sql.rb
index 7f74ebb402..8a5e1dbf25 100644
--- a/lib/arel/visitors/to_sql.rb
+++ b/lib/arel/visitors/to_sql.rb
@@ -336,6 +336,12 @@ module Arel
 
       def visit_Arel_Nodes_Window o, collector
         collector << "("
+
+        if o.partitions.any?
+          collector << "PARTITION BY "
+          collector = inject_join o.partitions, collector, ", "
+        end
+
         if o.orders.any?
           collector << "ORDER BY "
           collector = inject_join o.orders, collector, ", "