From 712714c90311c53150f5a7ca5f8241918df82411 Mon Sep 17 00:00:00 2001
From: Gregor Kleen <gregor.kleen@ifi.lmu.de>
Date: Fri, 8 May 2020 15:37:46 +0200
Subject: [PATCH] refactor: isomorphism for converting sqlbackend-keys

---
 src/Utils/Lens.hs | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/src/Utils/Lens.hs b/src/Utils/Lens.hs
index 8edf94784..d75fcb68b 100644
--- a/src/Utils/Lens.hs
+++ b/src/Utils/Lens.hs
@@ -28,6 +28,8 @@ import qualified Database.Esqueleto as E (Value(..),InnerJoin(..))
 
 import qualified Data.CaseInsensitive as CI
 
+import Database.Persist.Sql (BackendKey(..))
+
 
 _PathPiece :: PathPiece v => Prism' Text v
 _PathPiece = prism' toPathPiece fromPathPiece
@@ -65,7 +67,17 @@ _Maybe = iso (is _Just) (bool Nothing (Just ()))
 _CI :: FoldCase s => Iso' (CI s) s
 _CI = iso CI.original CI.mk
 
-makeWrapped ''Textarea
+instance Wrapped SqlBackendKey where
+  type Unwrapped SqlBackendKey = Int64
+  _Wrapped' = iso unSqlBackendKey SqlBackendKey
+instance Rewrapped SqlBackendKey t
+
+_SqlKey' :: ToBackendKey SqlBackend record => Iso' (Key record) Int64
+_SqlKey' = iso fromSqlKey toSqlKey
+
+_SqlKey :: ToBackendKey SqlBackend record => Iso' (Key record) SqlBackendKey
+_SqlKey = _SqlKey' . _Unwrapped
+
 
 -----------------------------------
 -- Lens Definitions for our Types