Merge pull request #577 from vlopezj/master

Add `FromJSON` and `ToJSON` instances for `DiffTime`

Author: bergmark

Data/Aeson/Types/FromJSON.hs

@@ -101,7 +101,7 @@ import Data.Ratio ((%), Ratio)
 import Data.Scientific (Scientific)
 import Data.Tagged (Tagged(..))
 import Data.Text (Text, pack, unpack)
-import Data.Time (Day, LocalTime, NominalDiffTime, TimeOfDay, UTCTime, ZonedTime)
+import Data.Time (Day, DiffTime, LocalTime, NominalDiffTime, TimeOfDay, UTCTime, ZonedTime)
 import Data.Time.Format (parseTime)
 import Data.Time.Locale.Compat (defaultTimeLocale)
 import Data.Traversable as Tr (sequence)
@@ -1704,6 +1704,15 @@ instance FromJSON NominalDiffTime where
     parseJSON = withScientific "NominalDiffTime" $ pure . realToFrac
     {-# INLINE parseJSON #-}
 
+
+-- | /WARNING:/ Only parse lengths of time from trusted input
+-- since an attacker could easily fill up the memory of the target
+-- system by specifying a scientific number with a big exponent like
+-- @1e1000000000@.
+instance FromJSON DiffTime where
+    parseJSON = withScientific "DiffTime" $ pure . realToFrac
+    {-# INLINE parseJSON #-}
+
 -------------------------------------------------------------------------------
 -- base Monoid/Semigroup
 -------------------------------------------------------------------------------

Data/Aeson/Types/ToJSON.hs

@@ -84,7 +84,7 @@ import Data.Ratio (Ratio, denominator, numerator)
 import Data.Scientific (Scientific)
 import Data.Tagged (Tagged(..))
 import Data.Text (Text, pack)
-import Data.Time (Day, LocalTime, NominalDiffTime, TimeOfDay, UTCTime, ZonedTime)
+import Data.Time (Day, DiffTime, LocalTime, NominalDiffTime, TimeOfDay, UTCTime, ZonedTime)
 import Data.Time.Format (FormatTime, formatTime)
 import Data.Time.Locale.Compat (defaultTimeLocale)
 import Data.Vector (Vector)
@@ -1911,13 +1911,22 @@ stringEncoding = String
     . E.encodingToLazyByteString
 {-# INLINE stringEncoding #-}
 
+
 instance ToJSON NominalDiffTime where
     toJSON = Number . realToFrac
     {-# INLINE toJSON #-}
 
     toEncoding = E.scientific . realToFrac
     {-# INLINE toEncoding #-}
 
+
+instance ToJSON DiffTime where
+    toJSON = Number . realToFrac
+    {-# INLINE toJSON #-}
+
+    toEncoding = E.scientific . realToFrac
+    {-# INLINE toEncoding #-}
+
 -------------------------------------------------------------------------------
 -- base Monoid/Semigroup
 -------------------------------------------------------------------------------

changelog.md

@@ -1,5 +1,9 @@
 For the latest version of this document, please see [https://github.com/bos/aeson/blob/master/changelog.md](https://github.com/bos/aeson/blob/master/changelog.md).
 
+## Upcoming
+
+* Add `FromJSON` and `ToJSON` instances for `DiffTime`, thanks to Víctor López Juan
+
 ## 1.2.1.0
 
 * Add `parserThrowError` and `parserCatchError` combinators, thanks to Oleg Grenrus.

tests/Properties.hs

@@ -27,7 +27,7 @@ import Data.Proxy (Proxy)
 import Data.Ratio (Ratio)
 import Data.Sequence (Seq)
 import Data.Tagged (Tagged)
-import Data.Time (Day, LocalTime, NominalDiffTime, TimeOfDay, UTCTime, ZonedTime)
+import Data.Time (Day, DiffTime, LocalTime, NominalDiffTime, TimeOfDay, UTCTime, ZonedTime)
 import Data.Version (Version)
 import Encoders
 import Instances ()
@@ -248,6 +248,7 @@ tests = testGroup "properties" [
     , testProperty "UTCTime" $ roundTripEq (undefined :: UTCTime)
     , testProperty "ZonedTime" $ roundTripEq (undefined :: ZonedTime)
     , testProperty "NominalDiffTime" $ roundTripEq (undefined :: NominalDiffTime)
+    , testProperty "DiffTime" $ roundTripEq (undefined :: DiffTime)
     , testProperty "Version" $ roundTripEq (undefined :: Version)
     , testProperty "Natural" $ roundTripEq (undefined :: Natural)
     , testProperty "Proxy" $ roundTripEq (undefined :: Proxy Int)