From b9d02ff8bec95cfba3ecf3060d524948f4f49680 Mon Sep 17 00:00:00 2001
From: Philipp Balzarek <p.balzarek@googlemail.com>
Date: Wed, 7 Mar 2018 15:39:25 +0100
Subject: [PATCH] Add arrayRemoveNull function (Postgresql)

---
 src/Database/Esqueleto/PostgreSQL.hs |  6 ++++++
 test/PostgreSQL/Test.hs              | 21 ++++++++++++++++++++-
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/src/Database/Esqueleto/PostgreSQL.hs b/src/Database/Esqueleto/PostgreSQL.hs
index 8982c3f..b45be5b 100644
--- a/src/Database/Esqueleto/PostgreSQL.hs
+++ b/src/Database/Esqueleto/PostgreSQL.hs
@@ -7,6 +7,7 @@ module Database.Esqueleto.PostgreSQL
   ( arrayAggDistinct
   , arrayAgg
   , arrayRemove
+  , arrayRemoveNull
   , stringAgg
   , chr
   , now_
@@ -48,6 +49,11 @@ arrayAgg = unsafeSqlFunction "array_agg"
 arrayRemove :: SqlExpr (Value [a]) -> SqlExpr (Value a) -> SqlExpr (Value [a])
 arrayRemove arr elem' = unsafeSqlFunction "array_remove" (arr, elem')
 
+-- | Remove @NULL@ values from an array
+arrayRemoveNull :: SqlExpr (Value [Maybe a]) -> SqlExpr (Value [a])
+arrayRemoveNull x = unsafeSqlFunction "array_remove" (x, unsafeSqlValue "NULL")
+
+
 -- | (@string_agg@) Concatenate input values separated by a
 -- delimiter.
 --
diff --git a/test/PostgreSQL/Test.hs b/test/PostgreSQL/Test.hs
index 00ce7e0..e9a3c72 100644
--- a/test/PostgreSQL/Test.hs
+++ b/test/PostgreSQL/Test.hs
@@ -237,6 +237,25 @@ testSelectDistinctOn = do
 
 
 
+testArrayRemoveNull :: SpecWith (Arg (IO ()))
+testArrayRemoveNull = do
+  describe "array_remove (NULL)" $ do
+    it "removes NULL from arrays from nullable fields" $ run $ do
+      mapM_ insert [ Person "1" Nothing   Nothing 1
+                   , Person "2" (Just 7)  Nothing 1
+                   , Person "3" (Nothing) Nothing 1
+                   , Person "4" (Just 8)  Nothing 2
+                   , Person "5" (Just 9)  Nothing 2
+                   ]
+      ret <- select . from $ \(person :: SqlExpr (Entity Person)) -> do
+        groupBy (person ^. PersonFavNum)
+        return . EP.arrayRemoveNull $ EP.arrayAgg (person ^. PersonAge)
+      liftIO $ (L.sort $ map (L.sort . unValue) ret) `shouldBe` [[7], [8,9]]
+
+
+
+
+
 testPostgresModule :: Spec
 testPostgresModule = do
   describe "PostgreSQL module" $ do
@@ -317,7 +336,7 @@ run =
 
 
 verbose :: Bool
-verbose = False
+verbose = True
 
 migrateIt :: RunDbMonad m => SqlPersistT (R.ResourceT m) ()
 migrateIt = do