Guests can pay with CB or coins, lot of other improvements

apps/note/api/serializers.py

@@ -163,6 +163,7 @@ class SpecialTransactionSerializer(serializers.ModelSerializer):
         fields = '__all__'
 
 
+# noinspection PyUnresolvedReferences
 class TransactionPolymorphicSerializer(PolymorphicSerializer):
     model_serializer_mapping = {
         Transaction: TransactionSerializer,
@@ -171,5 +172,12 @@ class TransactionPolymorphicSerializer(PolymorphicSerializer):
         SpecialTransaction: SpecialTransactionSerializer,
     }
 
+    try:
+        from activity.models import GuestTransaction
+        from activity.api.serializers import GuestTransactionSerializer
+        model_serializer_mapping[GuestTransaction] = GuestTransactionSerializer
+    except ImportError:  # Activity app is not loaded
+        pass
+
     class Meta:
         model = Transaction