Add BillingAddress structure to users

uncloud_django_based/uncloud/uncloud_pay/serializers.py

@@ -69,3 +69,15 @@ class BillSerializer(serializers.ModelSerializer):
         model = Bill
         fields = ['reference', 'owner', 'total', 'due_date', 'creation_date',
                 'starting_date', 'ending_date', 'records', 'final']
+
+class BillingAddressSerializer(serializers.ModelSerializer):
+    class Meta:
+        model = BillingAddress
+        fields = ['uuid', 'street', 'city', 'postal_code', 'country', 'vat_number']
+
+# We do not want users to mutate the country / VAT number of an address, as it
+# will change VAT on existing bills.
+class UpdateBillingAddressSerializer(serializers.ModelSerializer):
+    class Meta:
+        model = BillingAddress
+        fields = ['uuid', 'street', 'city', 'postal_code']