Add commit to have updated model objects in return.

accountant/views/operations.py

@@ -143,6 +143,8 @@ class OperationListResource(Resource):
 
         db.session.add(operation)  # pylint: disable=no-member
 
+        db.session.commit()
+
         return operation, 201
 
 
@@ -203,6 +205,8 @@ class OperationResource(Resource):
 
         db.session.merge(operation)  # pylint: disable=no-member
 
+        db.session.commit()
+
         return operation, 200
 
     @ns.response(204, 'Operation deleted', operation_model)