From 4b6490e037944b6e211cff17a99205a1d5ffd060 Mon Sep 17 00:00:00 2001
From: Michael Snoyman <michael@snoyman.com>
Date: Tue, 17 Apr 2012 18:30:40 +0300
Subject: [PATCH] Generalize hiddenField to any PathPiece

---
 yesod-form/Yesod/Form/Fields.hs | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/yesod-form/Yesod/Form/Fields.hs b/yesod-form/Yesod/Form/Fields.hs
index 81f37bf1..16598089 100644
--- a/yesod-form/Yesod/Form/Fields.hs
+++ b/yesod-form/Yesod/Form/Fields.hs
@@ -76,7 +76,7 @@ import qualified Data.Map as Map
 import Yesod.Handler (newIdent, lift)
 import Yesod.Request (FileInfo)
 
-import Yesod.Core (toPathPiece, GHandler, PathPiece)
+import Yesod.Core (toPathPiece, GHandler, PathPiece, fromPathPiece)
 import Yesod.Persist (selectList, runDB, Filter, SelectOpt, YesodPersistBackend, Key, YesodPersist, PersistEntity, PersistQuery)
 import Control.Arrow ((&&&))
 
@@ -178,11 +178,12 @@ textareaField = Field
 |]
     }
 
-hiddenField :: RenderMessage master FormMessage => Field sub master Text
+hiddenField :: (PathPiece p, RenderMessage master FormMessage)
+            => Field sub master p
 hiddenField = Field
-    { fieldParse = blank $ Right
+    { fieldParse = blank $ maybe (Left MsgValueRequired) Right . fromPathPiece
     , fieldView = \theId name attrs val _isReq -> toWidget [hamlet|
-<input type="hidden" id="#{theId}" name="#{name}" *{attrs} value="#{either id id val}">
+<input type="hidden" id="#{theId}" name="#{name}" *{attrs} value="#{either id toPathPiece val}">
 |]
     }