forked from OSS/graphql
39 lines
1.6 KiB
Haskell
39 lines
1.6 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 Data.GraphQL.Execute (execute) where
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import Control.Applicative (Alternative, empty)
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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 Data.HashMap.Strict as HashMap
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import qualified Data.GraphQL.AST as AST
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import qualified Data.GraphQL.AST.Core as AST.Core
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import qualified Data.GraphQL.AST.Transform as Transform
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import Data.GraphQL.Schema (Schema)
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import qualified Data.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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:: (Alternative f, Monad f)
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=> Schema f -> Schema.Subs -> AST.Document -> f Aeson.Value
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execute schema subs doc = document schema =<< maybe empty pure (Transform.document subs doc)
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document :: Alternative f => Schema f -> AST.Core.Document -> f Aeson.Value
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document schema (op :| []) = operation schema op
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document _ _ = error "Multiple operations not supported yet"
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operation :: Alternative f => Schema f -> AST.Core.Operation -> f Aeson.Value
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operation schema (AST.Core.Query flds) =
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Aeson.Object . HashMap.singleton "data"
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<$> Schema.resolve (NE.toList schema) (NE.toList flds)
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operation _ _ = error "Mutations not supported yet"
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