Morpheus GraphQL

AboutServerClientExamplesNamed Resolvers

Morpheus GraphQL Client with Template haskell QuasiQuotes

defineByDocumentFile "./schema.gql" [gql| query GetHero ($character: Character) { deity (fatherOf:$character) { name power worships { deity2Name: name } } } |]

with schema:

input Character { name: String! } type Deity { name: String! worships: Deity power: Power! } enum Power { Lightning Teleportation Omniscience }

will validate query and Generate:

  • namespaced response and variable types
  • instance for Fetch typeClass
data GetHero = GetHero { deity: DeityDeity } -- from: {user data DeityDeity = DeityDeity { name: Text, worships: Maybe DeityWorshipsDeity power: Power } -- from: {deity{worships data DeityWorshipsDeity = DeityWorshipsDeity { name: Text, } data Power = PowerLightning | PowerTeleportation | PowerOmniscience data GetHeroArgs = GetHeroArgs { character: Character } data Character = Character { name: Person }

as you see, response type field name collision can be handled with GraphQL alias.

with fetch you can fetch well typed response GetHero.

fetchHero :: Args GetHero -> m (Either (FetchError GetHero) GetHero) fetchHero = fetch jsonRes args where args = GetHeroArgs {character = Person {name = "Zeus"}} jsonRes :: ByteString -> m ByteString jsonRes = <GraphQL APi>

in this case, jsonRes resolves a request into a response in some monad m.

A fetch resolver implementation against a real API may look like the following:

{-# LANGUAGE OverloadedStrings #-} import Data.ByteString.Lazy (ByteString) import qualified Data.ByteString.Char8 as C8 import Network.HTTP.Req resolver :: String -> ByteString -> IO ByteString resolver tok b = runReq defaultHttpConfig $ do let headers = header "Content-Type" "application/json" responseBody <$> req POST (https "swapi.graph.cool") (ReqBodyLbs b) lbsResponse headers

this is demonstrated in examples/src/Client/StarWarsClient.hs

types can be generated from introspection too:

defineByIntrospectionFile "./introspection.json"