new quantity support

src/budy/models/bundle.py

@@ -60,6 +60,13 @@ class Bundle(base.BudyBase):
         index = True
     )
 
+    quantity = appier.field(
+        type = commons.Decimal,
+        index = True,
+        initial = commons.Decimal(0.0),
+        safe = True
+    )
+
     sub_total = appier.field(
         type = commons.Decimal,
         index = True,
@@ -122,6 +129,9 @@ def validate(cls):
         return super(Bundle, cls).validate() + [
             appier.not_duplicate("key", cls._name()),
 
+            appier.not_null("quantity"),
+            appier.gte("quantity", 0.0),
+
             appier.not_null("sub_total"),
             appier.gte("sub_total", 0.0),
 
@@ -288,6 +298,7 @@ def empty_referrals_s(self):
 
     def calculate(self):
         lines = self.lines if hasattr(self, "lines") else []
+        self.quantity = sum(line.quantity for line in lines)
         self.sub_total = sum(line.total for line in lines)
         self.discount = self.calculate_discount()
         self.taxes = self.calculate_taxes()
@@ -359,10 +370,6 @@ def fix_sub_total_s(self):
         self.sub_total = self.total
         self.save()
 
-    @property
-    def quantity(self):
-        return sum(line.quantity for line in self.lines)
-
     @property
     def discountable(self):
         return self.sub_total