98 lines
3.4 KiB
Haskell
98 lines
3.4 KiB
Haskell
{- This Source Code Form is subject to the terms of the Mozilla Public License,
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v. 2.0. If a copy of the MPL was not distributed with this file, You can
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obtain one at https://mozilla.org/MPL/2.0/. -}
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{-# LANGUAGE ExplicitForAll #-}
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{-# LANGUAGE LambdaCase #-}
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-- | GraphQL validator.
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module Language.GraphQL.Validate
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( Error(..)
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, Path(..)
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, document
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, module Language.GraphQL.Validate.Rules
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) where
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import Control.Monad.Trans.Reader (Reader, asks, runReader)
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import Data.Foldable (foldrM)
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import Data.Sequence (Seq(..), (><), (|>))
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import qualified Data.Sequence as Seq
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import Data.Text (Text)
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import Language.GraphQL.AST.Document
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import Language.GraphQL.Type.Schema
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import Language.GraphQL.Validate.Rules
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data Context m = Context
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{ ast :: Document
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, schema :: Schema m
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, rules :: [Rule]
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}
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type ValidateT m = Reader (Context m) (Seq Error)
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-- | If an error can be associated to a particular field in the GraphQL result,
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-- it must contain an entry with the key path that details the path of the
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-- response field which experienced the error. This allows clients to identify
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-- whether a null result is intentional or caused by a runtime error.
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data Path
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= Segment Text -- ^ Field name.
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| Index Int -- ^ List index if a field returned a list.
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deriving (Eq, Show)
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-- | Validation error.
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data Error = Error
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{ message :: String
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, locations :: [Location]
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, path :: [Path]
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} deriving (Eq, Show)
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-- | Validates a document and returns a list of found errors. If the returned
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-- list is empty, the document is valid.
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document :: forall m. Schema m -> [Rule] -> Document -> Seq Error
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document schema' rules' document' =
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runReader (foldrM go Seq.empty document') context
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where
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context = Context
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{ ast = document'
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, schema = schema'
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, rules = rules'
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}
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go definition' accumulator = (accumulator ><) <$> definition definition'
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definition :: forall m. Definition -> ValidateT m
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definition = \case
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definition'@(ExecutableDefinition executableDefinition' _) -> do
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applied <- applyRules definition'
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children <- executableDefinition executableDefinition'
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pure $ children >< applied
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definition' -> applyRules definition'
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where
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applyRules definition' = foldr (ruleFilter definition') Seq.empty
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<$> asks rules
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ruleFilter definition' (DefinitionRule rule) accumulator
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| Just message' <- rule definition' =
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accumulator |> Error
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{ message = message'
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, locations = [definitionLocation definition']
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, path = []
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}
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| otherwise = accumulator
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definitionLocation (ExecutableDefinition _ location) = location
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definitionLocation (TypeSystemDefinition _ location) = location
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definitionLocation (TypeSystemExtension _ location) = location
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executableDefinition :: forall m. ExecutableDefinition -> ValidateT m
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executableDefinition (DefinitionOperation definition') =
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operationDefinition definition'
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executableDefinition (DefinitionFragment definition') =
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fragmentDefinition definition'
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operationDefinition :: forall m. OperationDefinition -> ValidateT m
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operationDefinition (SelectionSet _operation) =
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pure Seq.empty
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operationDefinition (OperationDefinition _type _name _variables _directives _selection) =
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pure Seq.empty
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fragmentDefinition :: forall m. FragmentDefinition -> ValidateT m
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fragmentDefinition _fragment = pure Seq.empty
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