graphql/tests/Test/StarWars/Schema.hs
Eugen Wissner 09135c581a Constrain base monad to MonadCatch
Let's try MonadThrow/MonadCatch. It looks nice at a first glance. The
monad transformer stack contains only the ReaderT, less lifts are
required. Exception subtyping is easier, the user can (and should)
define custom error types and throw them. And it is still possible to
use pure error handling, if someone doesn't like runtime exceptions or
need to run a query in a pure environment.

Fixes #42.
2020-07-17 07:05:03 +02:00

155 lines
5.2 KiB
Haskell

{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE ScopedTypeVariables #-}
module Test.StarWars.Schema
( schema
) where
import Control.Monad.Catch (MonadThrow(..), SomeException)
import Control.Monad.Trans.Reader (asks)
import qualified Data.HashMap.Strict as HashMap
import Data.Maybe (catMaybes)
import Data.Text (Text)
import Language.GraphQL.Type
import qualified Language.GraphQL.Type.In as In
import qualified Language.GraphQL.Type.Out as Out
import Test.StarWars.Data
import Prelude hiding (id)
-- See https://github.com/graphql/graphql-js/blob/master/src/__tests__/starWarsSchema.js
schema :: Schema (Either SomeException)
schema = Schema
{ query = queryType
, mutation = Nothing
, subscription = Nothing
}
where
queryType = Out.ObjectType "Query" Nothing [] $ HashMap.fromList
[ ("hero", heroFieldResolver)
, ("human", humanFieldResolver)
, ("droid", droidFieldResolver)
]
heroField = Out.Field Nothing (Out.NamedObjectType heroObject)
$ HashMap.singleton "episode"
$ In.Argument Nothing (In.NamedEnumType episodeEnum) Nothing
heroFieldResolver = ValueResolver heroField hero
humanField = Out.Field Nothing (Out.NamedObjectType heroObject)
$ HashMap.singleton "id"
$ In.Argument Nothing (In.NonNullScalarType string) Nothing
humanFieldResolver = ValueResolver humanField human
droidField = Out.Field Nothing (Out.NamedObjectType droidObject) mempty
droidFieldResolver = ValueResolver droidField droid
heroObject :: Out.ObjectType (Either SomeException)
heroObject = Out.ObjectType "Human" Nothing [] $ HashMap.fromList
[ ("id", idFieldType)
, ("name", nameFieldType)
, ("friends", friendsFieldType)
, ("appearsIn", appearsInField)
, ("homePlanet", homePlanetFieldType)
, ("secretBackstory", secretBackstoryFieldType)
, ("__typename", typenameFieldType)
]
where
homePlanetFieldType
= ValueResolver (Out.Field Nothing (Out.NamedScalarType string) mempty)
$ idField "homePlanet"
droidObject :: Out.ObjectType (Either SomeException)
droidObject = Out.ObjectType "Droid" Nothing [] $ HashMap.fromList
[ ("id", idFieldType)
, ("name", nameFieldType)
, ("friends", friendsFieldType)
, ("appearsIn", appearsInField)
, ("primaryFunction", primaryFunctionFieldType)
, ("secretBackstory", secretBackstoryFieldType)
, ("__typename", typenameFieldType)
]
where
primaryFunctionFieldType
= ValueResolver (Out.Field Nothing (Out.NamedScalarType string) mempty)
$ idField "primaryFunction"
typenameFieldType :: Resolver (Either SomeException)
typenameFieldType
= ValueResolver (Out.Field Nothing (Out.NamedScalarType string) mempty)
$ idField "__typename"
idFieldType :: Resolver (Either SomeException)
idFieldType
= ValueResolver (Out.Field Nothing (Out.NamedScalarType id) mempty)
$ idField "id"
nameFieldType :: Resolver (Either SomeException)
nameFieldType
= ValueResolver (Out.Field Nothing (Out.NamedScalarType string) mempty)
$ idField "name"
friendsFieldType :: Resolver (Either SomeException)
friendsFieldType
= ValueResolver (Out.Field Nothing fieldType mempty)
$ idField "friends"
where
fieldType = Out.ListType $ Out.NamedObjectType droidObject
appearsInField :: Resolver (Either SomeException)
appearsInField
= ValueResolver (Out.Field (Just description) fieldType mempty)
$ idField "appearsIn"
where
fieldType = Out.ListType $ Out.NamedEnumType episodeEnum
description = "Which movies they appear in."
secretBackstoryFieldType :: Resolver (Either SomeException)
secretBackstoryFieldType = ValueResolver field secretBackstory
where
field = Out.Field Nothing (Out.NamedScalarType string) mempty
idField :: Text -> Resolve (Either SomeException)
idField f = do
v <- asks values
let (Object v') = v
pure $ v' HashMap.! f
episodeEnum :: EnumType
episodeEnum = EnumType "Episode" (Just description)
$ HashMap.fromList [newHope, empire, jedi]
where
description = "One of the films in the Star Wars Trilogy"
newHope = ("NEW_HOPE", EnumValue $ Just "Released in 1977.")
empire = ("EMPIRE", EnumValue $ Just "Released in 1980.")
jedi = ("JEDI", EnumValue $ Just "Released in 1983.")
hero :: Resolve (Either SomeException)
hero = do
episode <- argument "episode"
pure $ character $ case episode of
Enum "NEW_HOPE" -> getHero 4
Enum "EMPIRE" -> getHero 5
Enum "JEDI" -> getHero 6
_ -> artoo
human :: Resolve (Either SomeException)
human = do
id' <- argument "id"
case id' of
String i -> pure $ maybe Null character $ getHuman i >>= Just
_ -> throwM InvalidArguments
droid :: Resolve (Either SomeException)
droid = do
id' <- argument "id"
case id' of
String i -> pure $ maybe Null character $ getDroid i >>= Just
_ -> throwM InvalidArguments
character :: Character -> Value
character char = Object $ HashMap.fromList
[ ("id", String $ id_ char)
, ("name", String $ name_ char)
, ("friends", List $ character <$> getFriends char)
, ("appearsIn", List $ Enum <$> catMaybes (getEpisode <$> appearsIn char))
, ("homePlanet", String $ either mempty homePlanet char)
, ("__typename", String $ typeName char)
]