products/models.py: add UPC class

products/dbrouters.py

@@ -1,14 +1,20 @@
-from products.models import Product, SeasonRegionMaterial
+from products.models import Product, SeasonRegionMaterial, UPC
 
 
 class ProductDBRouter(object):
 
+    def is_product_class(self, model):
+        return \
+            model == Product or \
+            model == SeasonRegionMaterial or \
+            model == UPC
+
     def db_for_read(self, model, **hints):
-        if model == Product or model == SeasonRegionMaterial:
+        if self.is_product_class(model):
             return 'products'
         return None
 
     def db_for_write(self, model, **hints):
-        if model == Product or model == SeasonRegionMaterial:
+        if self.is_product_class(model):
             return 'products'
         return None