forked from OSS/graphql
69 lines
3.0 KiB
Haskell
69 lines
3.0 KiB
Haskell
-- | This module provides the function to execute a @GraphQL@ request --
|
|
-- according to a 'Schema'.
|
|
module Data.GraphQL.Execute (execute) where
|
|
|
|
import Control.Applicative (Alternative, empty)
|
|
import qualified Data.List.NonEmpty as NE
|
|
import Data.List.NonEmpty (NonEmpty((:|)))
|
|
|
|
import qualified Data.Aeson as Aeson
|
|
|
|
import qualified Data.GraphQL.AST as AST
|
|
import qualified Data.GraphQL.AST.Core as AST.Core
|
|
import qualified Data.GraphQL.AST.Transform as Transform
|
|
import Data.GraphQL.Schema (Schema)
|
|
import qualified Data.GraphQL.Schema as Schema
|
|
|
|
-- | Takes a 'Schema', a variable substitution function ('Schema.Subs'), and a
|
|
-- @GraphQL@ 'document'. The substitution is applied to the document using
|
|
-- 'rootFields', and the 'Schema''s resolvers are applied to the resulting fields.
|
|
--
|
|
-- Returns the result of the query against the 'Schema' wrapped in a /data/ field, or
|
|
-- errors wrapped in an /errors/ field.
|
|
execute
|
|
:: (Alternative f, Monad f)
|
|
=> Schema f -> Schema.Subs -> AST.Document -> f Aeson.Value
|
|
execute schema subs doc = document schema =<< maybe empty pure (Transform.document subs doc)
|
|
|
|
document :: Alternative f => Schema f -> AST.Core.Document -> f Aeson.Value
|
|
document schema (op :| [])= operation schema op
|
|
document _ _ = error "Multiple operations not supported yet"
|
|
|
|
operation :: Alternative f => Schema f -> AST.Core.Operation -> f Aeson.Value
|
|
operation schema (AST.Core.Query flds) =
|
|
Schema.resolve (NE.toList schema) (NE.toList flds)
|
|
operation _ _ = error "Mutations not supported yet"
|
|
|
|
-- | Takes a variable substitution function and a @GraphQL@ document.
|
|
-- If the document contains one query (and no other definitions)
|
|
-- it applies the substitution to the query's set of selections
|
|
-- and then returns their fields.
|
|
-- rootFields :: Schema.Subs -> Document -> [Field]
|
|
-- rootFields subs (Document [DefinitionOperation (Query (Node _varDefs _ _ sels))]) =
|
|
-- Schema.fields $ substitute subs <$> sels
|
|
-- rootFields _ _ = []
|
|
|
|
-- | Takes a variable substitution function and a selection. If the
|
|
-- selection is a field it applies the substitution to the field's
|
|
-- arguments using 'subsArg', and recursively applies the substitution to
|
|
-- the arguments of fields nested in the primary field.
|
|
-- 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
|
|
-- | Takes a variable substitution function and an argument. If the
|
|
-- argument's value is a variable the substitution is applied to the
|
|
-- variable's name.
|
|
-- subsArg :: Schema.Subs -> Argument -> Maybe Argument
|
|
-- subsArg subs (Argument n (ValueVariable (Variable v))) =
|
|
-- Argument n . ValueString <$> subs v
|
|
-- subsArg _ arg = Just arg
|