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

@@ -137,19 +137,34 @@
       #   x.union(y, z) # => UNION x, y, z
       def union(*relations)
         Union.new(*([self] + relations))
       end
 
+      def field(name)
+        type = schema.field_type(name) rescue nil
+        Field::Reference.new(name, self, :type => type)
+      end
+      
+      def schema
+        if @sources.nil?
+          raise Piglet::Schema::SchemaError, 'Could not determine the schema since there was no source relation and this relation does not define its own schema'
+        elsif @sources.size > 1
+          raise Piglet::Schema::SchemaError, 'Could not determine the schema since there were more than one source relation'
+        else
+          @sources.first.schema
+        end
+      end
+
       def method_missing(name, *args)
         if name.to_s =~ /^\w+$/ && args.empty?
-          Field::Reference.new(name, self)
+          field(name)
         else
           super
         end
       end
     
       def [](n)
-        Field::Reference.new("\$#{n}", self)
+        field("\$#{n}")
       end
 
       def hash
         self.alias.hash
       end
\ No newline at end of file