64 lines
2.6 KiB
Haskell
64 lines
2.6 KiB
Haskell
{-# LANGUAGE OverloadedStrings #-}
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-- | This module provides functions to execute a @GraphQL@ request.
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module Language.GraphQL.Execute
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( execute
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, module Language.GraphQL.Execute.Coerce
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) where
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import Control.Monad.Catch (MonadCatch)
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import Data.HashMap.Strict (HashMap)
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import Data.Sequence (Seq(..))
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import Data.Text (Text)
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import Language.GraphQL.AST.Document (Document, Name)
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import Language.GraphQL.Execute.Coerce
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import Language.GraphQL.Execute.Execution
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import qualified Language.GraphQL.Execute.Transform as Transform
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import qualified Language.GraphQL.Execute.Subscribe as Subscribe
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import Language.GraphQL.Error
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import qualified Language.GraphQL.Type.Definition as Definition
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import qualified Language.GraphQL.Type.Out as Out
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import Language.GraphQL.Type.Schema
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-- | The substitution is applied to the document, and the resolvers are applied
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-- to the resulting fields. The operation name can be used if the document
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-- defines multiple root operations.
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--
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-- Returns the result of the query against the schema wrapped in a /data/
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-- field, or errors wrapped in an /errors/ field.
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execute :: (MonadCatch m, VariableValue a, Serialize b)
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=> Schema m -- ^ Resolvers.
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-> Maybe Text -- ^ Operation name.
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-> HashMap Name a -- ^ Variable substitution function.
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-> Document -- @GraphQL@ document.
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-> m (Either (ResponseEventStream m b) (Response b))
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execute schema' operationName subs document =
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case Transform.document schema' operationName subs document of
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Left queryError -> pure
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$ Right
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$ singleError
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$ Transform.queryError queryError
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Right transformed -> executeRequest transformed
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executeRequest :: (MonadCatch m, Serialize a)
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=> Transform.Document m
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-> m (Either (ResponseEventStream m a) (Response a))
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executeRequest (Transform.Document types' rootObjectType operation)
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| (Transform.Query _ fields) <- operation =
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Right <$> executeOperation types' rootObjectType fields
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| (Transform.Mutation _ fields) <- operation =
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Right <$> executeOperation types' rootObjectType fields
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| (Transform.Subscription _ fields) <- operation
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= either (Right . singleError) Left
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<$> Subscribe.subscribe types' rootObjectType fields
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-- This is actually executeMutation, but we don't distinguish between queries
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-- and mutations yet.
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executeOperation :: (MonadCatch m, Serialize a)
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=> HashMap Name (Type m)
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-> Out.ObjectType m
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-> Seq (Transform.Selection m)
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-> m (Response a)
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executeOperation types' objectType fields =
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runCollectErrs types' $ executeSelectionSet Definition.Null objectType fields
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