.

generic/models.py

@@ -64,7 +64,7 @@ class ExamBase(models.Model):
         help_text="If the json cache needs updating", default=False
     )
 
-    json_creation_time = models.DateTimeField(blank=True)
+    json_creation_time = models.DateTimeField(blank=True, default=None, null=True)
 
     #time_limit = models.IntegerField(
     #    help_text="Exam time limit (in seconds). Default is 2100 secondse (35 minutes)",

generic/views.py

@@ -319,13 +319,17 @@ class ExamViews(View, LoginRequiredMixin):
 
         for exam in exams:
             if exam.active:
+                if exam.json_creation_time:
+                    creation_time = exam.json_creation_time.isoformat()
+                else:
+                    creation_time = "None"
                 active_exams["exams"].append(
                     {
                         "name": exam.get_exam_name(),
                         "url": request.build_absolute_uri(exam.get_json_url()),
                         "type": self.question_type,
                         "eid": "{}/{}".format(self.question_type, exam.pk),
-                        "json_creation_time": exam.json_creation_time.isoformat()
+                        "json_creation_time": creation_time
                     }
                 )