Aggiunto modulo per la conversione degli oggetti in JSON

models/department.py

@@ -19,11 +19,11 @@ class Department:
     def location_id(self) -> Location:
         return self.__location
 
-    def to_json(self):
+    def __json__(self):
         return {
             'department_id': self.__department_id,
             'name': self.__name,
-            'location': self.__location.to_json() if self.__location is not None else None
+            'location': self.__location if self.__location is not None else None
         }
 
     def __str__(self):