From 3bfe0bdcb79b398a387e202c5150b5e6fd230d3a Mon Sep 17 00:00:00 2001
From: Gregor Kleen <gkleen@yggdrasil.li>
Date: Thu, 16 Mar 2017 01:19:07 +0100
Subject: More complicated date handling
---
Model/Types.hs | 35 +++++++++++++++++++++++++++++++++++
1 file changed, 35 insertions(+)
create mode 100644 Model/Types.hs
(limited to 'Model')
diff --git a/Model/Types.hs b/Model/Types.hs
new file mode 100644
index 0000000..61bebfd
--- /dev/null
+++ b/Model/Types.hs
@@ -0,0 +1,35 @@
+{-# LANGUAGE DeriveGeneric #-}
+
+module Model.Types
+ ( ItemDate(..)
+ , isNever, isUnknown, isKnown
+ ) where
+
+import ClassyPrelude.Yesod
+
+data ItemDate = DateUnknown | DateKnown Day | DateNever
+ deriving (Eq, Ord, Show, Read, Generic)
+
+isNever, isUnknown, isKnown :: ItemDate -> Bool
+isNever DateNever = True
+isNever _ = False
+isUnknown DateUnknown = True
+isUnknown _ = False
+isKnown (DateKnown _) = True
+isKnown _ = False
+
+unknownVerb :: IsString a => a
+unknownVerb = "unknown"
+
+instance ToJSON ItemDate where
+ toJSON DateNever = Null
+ toJSON DateUnknown = String unknownVerb
+ toJSON (DateKnown d) = toJSON d
+instance FromJSON ItemDate where
+ parseJSON Null = pure DateNever
+ parseJSON v@(String inp)
+ | unknownVerb == inp = pure DateUnknown
+ | otherwise = DateKnown <$> parseJSON v
+ parseJSON v = DateKnown <$> parseJSON v
+
+derivePersistFieldJSON "ItemDate"
--
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