graphql/Data/GraphQL/Execute.hs

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{-# LANGUAGE CPP #-}
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module Data.GraphQL.Execute (execute) where
#if !MIN_VERSION_base(4,8,0)
import Control.Applicative ((<$>))
#endif
import Control.Applicative (Alternative)
import Data.Maybe (catMaybes)
import qualified Data.Aeson as Aeson
import Data.GraphQL.AST
import Data.GraphQL.Schema (Schema(..))
import qualified Data.GraphQL.Schema as Schema
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execute
:: Alternative f
=> Schema.Schema f -> Schema.Subs -> Document -> f Aeson.Value
execute (Schema resolvs) subs = Schema.resolvers resolvs . rootFields subs
rootFields :: Schema.Subs -> Document -> [Field]
rootFields subs (Document [DefinitionOperation (Query (Node _varDefs _ _ sels))]) =
Schema.fields $ substitute subs <$> sels
rootFields _ _ = []
substitute :: Schema.Subs -> Selection -> Selection
substitute subs (SelectionField (Field alias name args directives sels)) =
SelectionField $ Field
alias
name
-- TODO: Get rid of `catMaybes`, invalid arguments should raise an error
(catMaybes $ subsArg subs <$> args)
directives
(substitute subs <$> sels)
substitute _ sel = sel
-- TODO: Support different value types
subsArg :: Schema.Subs -> Argument -> Maybe Argument
subsArg subs (Argument n (ValueVariable (Variable v))) =
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Argument n . ValueString <$> subs v
subsArg _ arg = Just arg