TMSS-652: handle None parameters

SAS/TMSS/backend/src/tmss/tmssapp/reservations.py

@@ -6,8 +6,15 @@ def get_active_station_reservations_in_timewindow(lower_bound, upper_bound):
     Retrieve a list of all active stations reservations, which are reserved between a timewindow
     """
     lst_active_station_reservations = []
-    for res in models.Reservation.objects.filter(start_time__lt=upper_bound, stop_time__gt=lower_bound).values('specifications_doc'):
-        lst_active_station_reservations += res["specifications_doc"]["resources"]["stations"]
-    for res in models.Reservation.objects.filter(start_time__lt=upper_bound, stop_time=None).values('specifications_doc'):
+    if upper_bound is None:
+        queryset = models.Reservation.objects.filter(start_time__lt=upper_bound)
+    else:
+        queryset = models.Reservation.objects.all()
+
+    for res in queryset.filter(stop_time=None).values('specifications_doc'):
         lst_active_station_reservations += res["specifications_doc"]["resources"]["stations"]
+
+    if lower_bound is not None:
+        for res in queryset.filter(stop_time__gt=lower_bound).values('specifications_doc'):
+            lst_active_station_reservations += res["specifications_doc"]["resources"]["stations"]
     return list(set(lst_active_station_reservations))