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include key in error message from getField functions #44

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Merged
merged 6 commits into from
Jun 27, 2018
Merged

include key in error message from getField functions #44

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a91f9dd
include key in error message from getField functions
Jun 22, 2018
a17f7c2
add explicit exports to Decode.Combinators
Jun 23, 2018
9c75838
add infix operators to exports for Decode.Combinators
Jun 26, 2018
da2e0b1
include index of failure in error message when decoding array
Jun 26, 2018
f4d75f1
update tests to use purescript-test-unit, and add one for the error m…
Jun 26, 2018
695f11e
remove transitive dependency on quickcheck
Jun 26, 2018
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11 changes: 9 additions & 2 deletions src/Data/Argonaut/Decode/Combinators.purs
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@ import Prelude

import Data.Argonaut.Core (Json)
import Data.Argonaut.Decode.Class (class DecodeJson, decodeJson)
import Data.Bifunctor (lmap)
import Data.Either (Either(..))
import Data.Maybe (Maybe(..), fromMaybe, maybe)
import Foreign.Object as FO
Expand All @@ -12,7 +13,7 @@ getField :: forall a. DecodeJson a => FO.Object Json -> String -> Either String
getField o s =
maybe
(Left $ "Expected field " <> show s)
decodeJson
(elaborateFailure s <<< decodeJson)
(FO.lookup s o)

infix 7 getField as .?
Expand All @@ -24,11 +25,17 @@ getFieldOptional o s =
decode
(FO.lookup s o)
where
decode json = Just <$> decodeJson json
decode json = Just <$> (elaborateFailure s <<< decodeJson) json

infix 7 getFieldOptional as .??

defaultField :: forall a. Either String (Maybe a) -> a -> Either String a
defaultField parser default = fromMaybe default <$> parser

infix 6 defaultField as .?=

elaborateFailure :: ∀ a. String -> Either String a -> Either String a
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We should make explicit exports for the module so we don't expose this function

elaborateFailure s e =
lmap msg e
where
msg m = "Failed to decode key '" <> s <> "': " <> m