From 782110a824405143f35ef13ab56e0c45d14b3435 Mon Sep 17 00:00:00 2001
From: Steffen Jost <jost@tcs.ifi.lmu.de>
Date: Wed, 19 Jun 2019 11:11:55 +0200
Subject: [PATCH] feat minor: E.isJust added

---
 src/Database/Esqueleto/Utils.hs | 7 ++++++-
 src/Handler/Corrections.hs      | 4 ++--
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/src/Database/Esqueleto/Utils.hs b/src/Database/Esqueleto/Utils.hs
index 38105a37a..bd8120ba7 100644
--- a/src/Database/Esqueleto/Utils.hs
+++ b/src/Database/Esqueleto/Utils.hs
@@ -2,6 +2,7 @@
 
 module Database.Esqueleto.Utils
   ( true, false
+  , isJust
   , isInfixOf, hasInfix
   , any, all
   , SqlIn(..)
@@ -11,7 +12,7 @@ module Database.Esqueleto.Utils
   , anyFilter, allFilter
   ) where
 
-import ClassyPrelude.Yesod hiding (isInfixOf, any, all)
+import ClassyPrelude.Yesod hiding (isInfixOf, any, all, isJust)
 import qualified Data.Set as Set
 import qualified Data.Foldable as F
 import qualified Database.Esqueleto as E
@@ -34,6 +35,10 @@ true  = E.val True
 false :: E.SqlExpr (E.Value Bool)
 false = E.val False
 
+-- | Negation of `isNothing` which is missing
+isJust :: (E.Esqueleto query expr backend, PersistField typ) => expr (E.Value (Maybe typ)) -> expr (E.Value Bool)
+isJust = E.not_ . E.isNothing
+
 -- | Check if the first string is contained in the text derived from the second argument
 isInfixOf :: (E.Esqueleto query expr backend, E.SqlString s2) =>
    Text -> expr (E.Value s2) -> expr (E.Value Bool)
diff --git a/src/Handler/Corrections.hs b/src/Handler/Corrections.hs
index dc8cb791e..92a60d00e 100644
--- a/src/Handler/Corrections.hs
+++ b/src/Handler/Corrections.hs
@@ -337,13 +337,13 @@ makeCorrectionsTable whereClause dbtColonnade dbtFilterUI psValidator dbtProj' d
       , ( "isassigned"
         , FilterColumn $  \((_ `E.InnerJoin` _ `E.InnerJoin` submission) `E.LeftOuterJoin` _ :: CorrectionTableExpr) criterion -> case getLast (criterion :: Last Bool) of
             Nothing -> E.val True :: E.SqlExpr (E.Value Bool)
-            Just True -> E.not_ . E.isNothing $ submission E.^. SubmissionRatingBy
+            Just True -> E.isJust    $ submission E.^. SubmissionRatingBy
             Just False-> E.isNothing $ submission E.^. SubmissionRatingBy
         )
       , ( "israted"
         , FilterColumn $  \((_ `E.InnerJoin` _ `E.InnerJoin` submission) `E.LeftOuterJoin` _ :: CorrectionTableExpr) criterion -> case getLast (criterion :: Last Bool) of
             Nothing -> E.val True :: E.SqlExpr (E.Value Bool)
-            Just True -> E.not_ . E.isNothing $ submission E.^. SubmissionRatingTime
+            Just True -> E.isJust    $ submission E.^. SubmissionRatingTime
             Just False-> E.isNothing $ submission E.^. SubmissionRatingTime
         )
       , ( "corrector-name-email" -- corrector filter does not work for text-filtering