.

longs/views.py

@@ -669,13 +669,24 @@ def mark_answer(request, pk, sk, cid):
         raise Http404("Exam question does not exist")
 
 
-    question.cid_user_answers.filter(exam__id=pk).values_list("cid", flat=True)
+    cid_list = question.cid_user_answers.filter(exam__id=pk).values_list("cid", flat=True)
 
     try:
         answer = question.cid_user_answers.get(cid=cid, exam__id=pk)
     except ObjectDoesNotExist:
         raise Http404("User answer does not exist")
 
+    previous_cid = False
+    next_cid = False
+
+    if cid_list[0] == cid:
+        next_cid = cid_list[1]
+    elif cid_list[-1] == cid:
+        previous_cid = cid_list[-2]
+    else:
+        next_cid = cid_list[cid_list.index(cid)+1]
+        previous_cid = cid_list[cid_list.index(cid)-1]
+
     try:
         unmarked = question.get_unmarked_answers()
         next_unmarked_id = unmarked[0].cid
@@ -720,6 +731,8 @@ def mark_answer(request, pk, sk, cid):
             "question_details": question_details,
             "next_unmarked_id": next_unmarked_id,
             "unmarked": unmarked,
+            "previous_cid": previous_cid,
+            "next_cid": next_cid,
         },
     )