src/Model/Types/DateTime.hs

@@ -29,7 +29,7 @@ import Data.Aeson.Types as Aeson
 
 newtype TermIdentifier = TermIdentifier { getTermDay :: Day }
     deriving (Show, Read, Eq, Ord, Generic, Typeable, Enum)     
-    deriving newtype (Binary, ISO8601)
+    deriving newtype (Binary, ISO8601, PersistField, PersistFieldSql)
     deriving anyclass (NFData)
     -- ought to be equivalent to deriving stock (Show, Read, Eq, Ord, Generic, Typeable, Enum, Binary, NFData)
 
@@ -102,6 +102,7 @@ termToRational = (dayOffset +) . (/ daysPerYear) . fromIntegral . fromEnum
 termFromRational :: Rational -> TermIdentifier
 termFromRational = toEnum . round . (daysPerYear *) . subtract dayOffset
 
+{- -- For newtype Day, PersistField instance can be derived automatically
 instance PersistField TermIdentifier where
   toPersistValue = PersistRational . termToRational
   fromPersistValue (PersistRational t) = Right $ termFromRational t
@@ -109,6 +110,7 @@ instance PersistField TermIdentifier where
 
 instance PersistFieldSql TermIdentifier where
   sqlType _ = SqlNumeric 9 5 -- total significant digits; significant digits after decimal point
+-}
 
 instance ToHttpApiData TermIdentifier where
   toUrlPiece = termToText