diff --git a/common/models/db_models.py b/common/models/db_models.py
index 223709c4..23b45696 100644
--- a/common/models/db_models.py
+++ b/common/models/db_models.py
@@ -52,7 +52,7 @@ def to_dict(self):
         dictionary = {}
         for column in self.__table__.columns:
             attribute = getattr(self, column.name)
-            dictionary[column.name] = str(attribute) if isinstance(attribute, datetime) else attribute
+            dictionary[column.name] = self._make_serializable(attribute)
         return dictionary
 
     def _make_serializable(self, field):