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|
{-# LANGUAGE DuplicateRecordFields #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE RecordWildCards #-}
-- | Error handling.
module Language.GraphQL.Error
( parseError
, CollectErrsT
, Error(..)
, Resolution(..)
, Response(..)
, addErr
, addErrMsg
, runCollectErrs
, singleError
) where
import Control.Monad.Trans.State (StateT, modify, runStateT)
import Data.HashMap.Strict (HashMap)
import Data.Sequence (Seq(..), (|>))
import qualified Data.Sequence as Seq
import Data.Text (Text)
import qualified Data.Text as Text
import Data.Void (Void)
import Language.GraphQL.AST.Document (Name)
import Language.GraphQL.Execute.Coerce
import Language.GraphQL.Type.Schema
import Prelude hiding (null)
import Text.Megaparsec
( ParseErrorBundle(..)
, PosState(..)
, SourcePos(..)
, errorOffset
, parseErrorTextPretty
, reachOffset
, unPos
)
-- | Executor context.
data Resolution m = Resolution
{ errors :: Seq Error
, types :: HashMap Name (Type m)
}
-- | Wraps a parse error into a list of errors.
parseError :: (Applicative f, Serialize a)
=> ParseErrorBundle Text Void
-> f (Response a)
parseError ParseErrorBundle{..} =
pure $ Response null $ fst
$ foldl go (Seq.empty, bundlePosState) bundleErrors
where
errorObject s SourcePos{..} = Error
(Text.pack $ init $ parseErrorTextPretty s)
(unPos' sourceLine)
(unPos' sourceColumn)
unPos' = fromIntegral . unPos
go (result, state) x =
let (_, newState) = reachOffset (errorOffset x) state
sourcePosition = pstateSourcePos newState
in (result |> errorObject x sourcePosition, newState)
-- | A wrapper to pass error messages around.
type CollectErrsT m = StateT (Resolution m) m
-- | Adds an error to the list of errors.
addErr :: Monad m => Error -> CollectErrsT m ()
addErr v = modify appender
where
appender :: Monad m => Resolution m -> Resolution m
appender resolution@Resolution{..} = resolution{ errors = errors |> v }
makeErrorMessage :: Text -> Error
makeErrorMessage s = Error s 0 0
-- | Constructs a response object containing only the error with the given
-- message.
singleError :: Serialize a => Text -> Response a
singleError message = Response null $ Seq.singleton $ makeErrorMessage message
-- | Convenience function for just wrapping an error message.
addErrMsg :: (Monad m, Serialize a) => Text -> CollectErrsT m a
addErrMsg errorMessage = (addErr . makeErrorMessage) errorMessage >> pure null
-- | @GraphQL@ error.
data Error = Error
{ message :: Text
, line :: Word
, column :: Word
} deriving (Eq, Show)
-- | The server\'s response describes the result of executing the requested
-- operation if successful, and describes any errors encountered during the
-- request.
data Response a = Response
{ data' :: a
, errors :: Seq Error
} deriving (Eq, Show)
-- | Runs the given query computation, but collects the errors into an error
-- list, which is then sent back with the data.
runCollectErrs :: (Monad m, Serialize a)
=> HashMap Name (Type m)
-> CollectErrsT m a
-> m (Response a)
runCollectErrs types' res = do
(dat, Resolution{..}) <- runStateT res
$ Resolution{ errors = Seq.empty, types = types' }
pure $ Response dat errors
|
