From 2e7bca6333deea697e98d4bd84a1aec6ef0c1f77 Mon Sep 17 00:00:00 2001
From: Sarah Vaupel <vaupel.sarah@campus.lmu.de>
Date: Thu, 23 Jan 2020 20:41:35 +0100
Subject: [PATCH] fix(exam-correct): fix returning null if old and new results
 are equal

---
 src/Handler/Exam/Correct.hs | 33 +++++++++++++++++++--------------
 1 file changed, 19 insertions(+), 14 deletions(-)

diff --git a/src/Handler/Exam/Correct.hs b/src/Handler/Exam/Correct.hs
index 79d86b9d6..c1c095096 100644
--- a/src/Handler/Exam/Correct.hs
+++ b/src/Handler/Exam/Correct.hs
@@ -147,20 +147,25 @@ postECorrectR tid ssh csh examn = do
                 delete oldId
                 audit $ TransactionExamPartResultDeleted examPartId uid
                 return Nothing
-              | Just partResult <- mPartResult
-              , fmap (examPartResultResult . entityVal) mOldResult /= fmap ExamAttended mPartResult -> do
-                newExamPartResult <- upsert ExamPartResult
-                  { examPartResultExamPart    = examPartId
-                  , examPartResultUser        = uid
-                  , examPartResultResult      = ExamAttended partResult
-                  , examPartResultLastChanged = now
-                  }
-                  [ ExamPartResultResult      =. ExamAttended partResult
-                  , ExamPartResultLastChanged =. now
-                  ]
-                audit $ TransactionExamPartResultEdit examPartId uid
-                return $ newExamPartResult ^? _entityVal . _examPartResultResult . _ExamAttended
-              | otherwise -> return Nothing
+              | Just partResult <- mPartResult -> let
+                  mOld = (examPartResultResult . entityVal) <$> mOldResult
+                  mNew = ExamAttended <$> mPartResult
+                  resultVal = _entityVal . _examPartResultResult . _ExamAttended
+                in if
+                  | mOld /= mNew -> do
+                    newExamPartResult <- upsert ExamPartResult
+                      { examPartResultExamPart    = examPartId
+                      , examPartResultUser        = uid
+                      , examPartResultResult      = ExamAttended partResult
+                      , examPartResultLastChanged = now
+                      }
+                      [ ExamPartResultResult      =. ExamAttended partResult
+                      , ExamPartResultLastChanged =. now
+                      ]
+                    audit $ TransactionExamPartResultEdit examPartId uid
+                    return $ newExamPartResult ^? resultVal
+                  | otherwise -> return $ mOldResult ^? _Just . resultVal
+                | otherwise -> return Nothing
         user <- userToResponse match
         return CorrectInterfaceResponseSuccess
           { cirsUser    = user