lib/piglet/relation/group.rb in piglet-0.1.2 vs lib/piglet/relation/group.rb in piglet-0.2.0

@@ -5,9 +5,25 @@
     
       def initialize(relation, grouping, options={})
         options ||= {}
         @sources, @grouping, @parallel = [relation], grouping, options[:parallel]
       end
+      
+      def schema
+        parent = @sources.first
+        parent_schema = parent.schema
+        if @grouping.size == 1
+          group_type = parent.schema.field_type(@grouping.first)
+        else
+          group_type = Piglet::Schema::Tuple.parse(
+            @grouping.map { |field| [field, parent_schema.field_type(field)] }
+          )
+        end
+        Piglet::Schema::Tuple.parse([
+          [:group, group_type],
+          [parent.alias.to_sym, Piglet::Schema::Bag.new(parent_schema)]
+        ])
+      end
     
       def to_s
         str = "GROUP #{@sources.first.alias} BY "
         if @grouping.size > 1
           str << "(#{@grouping.join(', ')})"
\ No newline at end of file