55 lines
1.8 KiB
Haskell
55 lines
1.8 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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-- | Definitions used by the validation rules and the validator itself.
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module Language.GraphQL.Validate.Validation
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( Error(..)
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, Path(..)
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, Rule(..)
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, RuleT
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, Validation(..)
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) where
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import Control.Monad.Trans.Reader (ReaderT(..))
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import Data.HashMap.Strict (HashMap)
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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 (Schema)
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import qualified Language.GraphQL.Type.Schema as Schema
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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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-- | Validation rule context.
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data Validation m = Validation
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{ ast :: Document
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, schema :: Schema m
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, types :: HashMap Name (Schema.Type m)
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, rules :: [Rule m]
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}
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-- | 'Rule' assigns a function to each AST node that can be validated. If the
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-- validation fails, the function should return an error message, or 'Nothing'
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-- otherwise.
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data Rule m
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= DefinitionRule (Definition -> RuleT m)
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| OperationDefinitionRule (OperationDefinition -> RuleT m)
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| FragmentDefinitionRule (FragmentDefinition -> RuleT m)
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-- | Monad transformer used by the rules.
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type RuleT m = ReaderT (Validation m) Maybe Error
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