LIL-267, LIL-271. Fix summary price

apps/payment/models.py

@@ -69,6 +69,9 @@ class CoursePayment(Payment):
                 amount=self.amount,
                 payment=self,
             )
+        else:
+            author_balance.amount = self.amount
+            author_balance.save()
 
 
 class SchoolPayment(Payment):
@@ -85,7 +88,7 @@ class SchoolPayment(Payment):
             weekday__in=self.weekdays,
         ).aggregate(
             models.Sum('month_price'),
-        ).month_price_sum
+        ).get('month_price__sum', 0)
         self.amount = month_price_sum
         super().save(*args, **kwargs)
         author_balance = getattr(self, 'authorbalance', None)
@@ -94,3 +97,6 @@ class SchoolPayment(Payment):
                 amount=month_price_sum,
                 payment=self,
             )
+        else:
+            author_balance.amount = self.amount
+            author_balance.save()