Morpheus GraphQL Client
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 String 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"