43 lines
1.7 KiB
Haskell
43 lines
1.7 KiB
Haskell
{-# LANGUAGE OverloadedStrings #-}
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-- | This module provides the function to execute a @GraphQL@ request --
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-- according to a 'Schema'.
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module Language.GraphQL.Execute
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( execute
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) where
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import Control.Monad.IO.Class (MonadIO)
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import qualified Data.List.NonEmpty as NE
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import Data.List.NonEmpty (NonEmpty((:|)))
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import qualified Data.Aeson as Aeson
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import qualified Language.GraphQL.AST as AST
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import qualified Language.GraphQL.AST.Core as AST.Core
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import qualified Language.GraphQL.AST.Transform as Transform
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import Language.GraphQL.Error
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import Language.GraphQL.Schema (Schema)
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import qualified Language.GraphQL.Schema as Schema
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-- | Takes a 'Schema', a variable substitution function ('Schema.Subs'), and a
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-- @GraphQL@ 'document'. The substitution is applied to the document using
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-- 'rootFields', and the 'Schema''s resolvers are applied to the resulting fields.
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--
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-- Returns the result of the query against the 'Schema' wrapped in a /data/ field, or
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-- errors wrapped in an /errors/ field.
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execute
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:: MonadIO m
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=> Schema m -> Schema.Subs -> AST.Document -> m Aeson.Value
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execute schema subs doc =
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maybe transformError (document schema) $ Transform.document subs doc
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where
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transformError = return $ singleError "Schema transformation error."
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document :: MonadIO m => Schema m -> AST.Core.Document -> m Aeson.Value
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document schema (op :| []) = operation schema op
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document _ _ = return $ singleError "Multiple operations not supported yet."
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operation :: MonadIO m => Schema m -> AST.Core.Operation -> m Aeson.Value
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operation schema (AST.Core.Query flds)
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= runCollectErrs (Schema.resolve (NE.toList schema) (NE.toList flds))
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operation schema (AST.Core.Mutation flds)
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= runCollectErrs (Schema.resolve (NE.toList schema) (NE.toList flds))
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