diff --git a/generic_trainer/configs.py b/generic_trainer/configs.py
index 84105cc..8bda505 100644
--- a/generic_trainer/configs.py
+++ b/generic_trainer/configs.py
@@ -36,13 +36,7 @@ def get_serializable_dict(self):
         d = {}
         for key in self.__dict__.keys():
             v = self.__dict__[key]
-            if not self.__class__.is_jsonable(v):
-                if isinstance(v, (tuple, list)):
-                    v = [str(x) for x in v]
-                elif isinstance(v, OptionContainer):
-                    v = v.get_serializable_dict()
-                else:
-                    v = str(v)
+            v = self.object_to_string(key, v)
             d[key] = v
         return d
 
@@ -62,7 +56,7 @@ def load_from_json(self, filename):
         f = open(filename, 'r')
         d = json.load(f)
         for key in d.keys():
-            self.__dict__[key] = d[key]
+            self.__dict__[key] = self.string_to_object(key, d[key])
         f.close()
 
     def string_to_object(self, key, value):
@@ -72,15 +66,22 @@ def string_to_object(self, key, value):
         :param value: str.
         :return: object.
         """
-        pass
+        return value
 
-    def object_to_string(self, key):
+    def object_to_string(self, key, value):
         """
         Convert an object in a config key to string.
         :param key: str.
+        :param value: object.
         :return: str.
         """
-        pass
+        if isinstance(value, OptionContainer):
+            value = value.get_serializable_dict()
+        elif isinstance(value, (tuple, list)):
+            value = [self.object_to_string(key, x) for x in value]
+        else:
+            value = str(value)
+        return value
 
 
 # =============================