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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"
|