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Respect subscriptions in the executor

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After the last commit there were a few places needed to be adjusted to
support subscriptions. This is done and a test case is added.

It is important to implement subscriptions now, because they require
changes to the library API, and they are a big missing part to finish
the executor. When the executor is finished, we can start to provide
more stable API without breaking everything every release. Validation
and introspection shouldn't require much changes to the API; AST would
require some changes to report good errors after the validation - this
is one thing I can think of.

Fixes #5.
This commit is contained in:
Eugen Wissner 2020-07-15 19:15:31 +02:00
parent ae2210f659
commit e24386402b
9 changed files with 132 additions and 81 deletions
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56
docs/tutorial/tutorial.lhs
View File

@ -5,7 +5,7 @@ title: GraphQL Haskell Tutorial
== Getting started ==
Welcome to graphql-haskell!
Welcome to GraphQL!
We have written a small tutorial to help you (and ourselves) understand the
graphql package.
@ -39,16 +39,18 @@ Now, as our first example, we are going to look at the example from
First we build a GraphQL schema.
> schema1 :: Schema IO
> schema1 = Schema queryType Nothing
> schema1 = Schema
> { query = queryType , mutation = Nothing , subscription = Nothing }
>
> queryType :: ObjectType IO
> queryType = ObjectType "Query" Nothing []
> $ HashMap.singleton "hello" helloField
> $ HashMap.singleton "hello"
> $ ValueResolver helloField hello
>
> helloField :: Field IO
> helloField = Field Nothing (Out.NamedScalarType string) mempty hello
> helloField = Field Nothing (Out.NamedScalarType string) mempty
>
> hello :: ResolverT IO Value
> hello :: Resolve IO
> hello = pure $ String "it's me"
This defines a simple schema with one type and one field, that resolves to a
@ -74,16 +76,18 @@ This runs the query by fetching the one field defined, returning
For this example, we're going to be using time.
> schema2 :: Schema IO
> schema2 = Schema queryType2 Nothing
> schema2 = Schema
> { query = queryType2, mutation = Nothing, subscription = Nothing }
>
> queryType2 :: ObjectType IO
> queryType2 = ObjectType "Query" Nothing []
> $ HashMap.singleton "time" timeField
> $ HashMap.singleton "time"
> $ ValueResolver timeField time
>
> timeField :: Field IO
> timeField = Field Nothing (Out.NamedScalarType string) mempty time
> timeField = Field Nothing (Out.NamedScalarType string) mempty
>
> time :: ResolverT IO Value
> time :: Resolve IO
> time = do
> t <- liftIO getCurrentTime
> pure $ String $ Text.pack $ show t
@ -104,42 +108,18 @@ This runs the query, returning the current time
```{"data": {"time":"2016-03-08 23:28:14.546899 UTC"}}```
=== Errors ===
Errors are handled according to the spec, with fields that cause erros being
resolved to `null`, and an error being added to the error list.
An example of this is the following query:
> queryShouldFail :: Text
> queryShouldFail = "{ boyhowdy }"
Since there is no `boyhowdy` field in our schema, it will not resolve, and the
query will fail, as we can see in the following example.
> mainShouldFail :: IO ()
> mainShouldFail = do
> failure <- graphql schema1 queryShouldFail
> putStrLn $ encode failure
This outputs:
```
{"data": {"boyhowdy": null}, "errors":[{"message": "the field boyhowdy did not resolve."}]}
```
=== Combining resolvers ===
Now that we have two resolvers, we can define a schema which uses them both.
> schema3 :: Schema IO
> schema3 = Schema queryType3 Nothing
> schema3 = Schema
> { query = queryType3, mutation = Nothing, subscription = Nothing }
>
> queryType3 :: ObjectType IO
> queryType3 = ObjectType "Query" Nothing [] $ HashMap.fromList
> [ ("hello", helloField)
> , ("time", timeField)
> [ ("hello", ValueResolver helloField hello)
> , ("time", ValueResolver timeField time)
> ]
>
> query3 :: Text
@ -166,4 +146,4 @@ directory, in the [Test.StarWars](../../tests/Test/StarWars) module. This
includes a more complex schema, and more complex queries.
> main :: IO ()
> main = main1 >> main2 >> mainShouldFail >> main3
> main = main1 >> main2 >> main3

27
src/Language/GraphQL/Execute/Execution.hs
View File

@ -107,17 +107,22 @@ executeField :: (Monad m, Serialize a)
-> Type.Value
-> NonEmpty (Transform.Field m)
-> CollectErrsT m a
executeField (Out.ValueResolver fieldDefinition resolver) prev fields = do
let Out.Field _ fieldType argumentDefinitions = fieldDefinition
let (Transform.Field _ _ arguments' _ :| []) = fields
case coerceArgumentValues argumentDefinitions arguments' of
Nothing -> addErrMsg "Argument coercing failed."
Just argumentValues -> do
answer <- lift $ resolveFieldValue prev argumentValues resolver
case answer of
Right result -> completeValue fieldType fields result
Left errorMessage -> addErrMsg errorMessage
executeField _ _ _ = addErrMsg "No field value resolver specified."
executeField fieldResolver prev fields
| Out.ValueResolver fieldDefinition resolver <- fieldResolver =
executeField' fieldDefinition resolver
| Out.EventStreamResolver fieldDefinition resolver _ <- fieldResolver =
executeField' fieldDefinition resolver
where
executeField' fieldDefinition resolver = do
let Out.Field _ fieldType argumentDefinitions = fieldDefinition
let (Transform.Field _ _ arguments' _ :| []) = fields
case coerceArgumentValues argumentDefinitions arguments' of
Nothing -> addErrMsg "Argument coercing failed."
Just argumentValues -> do
answer <- lift $ resolveFieldValue prev argumentValues resolver
case answer of
Right result -> completeValue fieldType fields result
Left errorMessage -> addErrMsg errorMessage
completeValue :: (Monad m, Serialize a)
=> Out.Type m

4
src/Language/GraphQL/Execute/Transform.hs
View File

@ -239,6 +239,10 @@ document schema operationName subs ast = do
| Just mutationType <- mutation schema ->
pure $ Document referencedTypes mutationType
$ operation chosenOperation replacement
OperationDefinition Full.Subscription _ _ _ _
| Just subscriptionType <- subscription schema ->
pure $ Document referencedTypes subscriptionType
$ operation chosenOperation replacement
_ -> Left UnsupportedRootOperation
defragment

1
src/Language/GraphQL/Type/Schema.hs
View File

@ -29,4 +29,5 @@ data Type m
data Schema m = Schema
{ query :: Out.ObjectType m
, mutation :: Maybe (Out.ObjectType m)
, subscription :: Maybe (Out.ObjectType m)
}

96
tests/Language/GraphQL/ExecuteSpec.hs
View File

@ -1,3 +1,7 @@
{- This Source Code Form is subject to the terms of the Mozilla Public License,
v. 2.0. If a copy of the MPL was not distributed with this file, You can
obtain one at https://mozilla.org/MPL/2.0/. -}
{-# LANGUAGE OverloadedStrings #-}
module Language.GraphQL.ExecuteSpec
( spec
@ -5,6 +9,7 @@ module Language.GraphQL.ExecuteSpec
import Data.Aeson ((.=))
import qualified Data.Aeson as Aeson
import Data.Conduit
import Data.Either (fromRight)
import Data.Functor.Identity (Identity(..))
import Data.HashMap.Strict (HashMap)
@ -15,11 +20,15 @@ import Language.GraphQL.Error
import Language.GraphQL.Execute
import Language.GraphQL.Type as Type
import Language.GraphQL.Type.Out as Out
import Test.Hspec (Spec, describe, it, shouldBe)
import Test.Hspec (Spec, context, describe, it, shouldBe)
import Text.Megaparsec (parse)
schema :: Schema Identity
schema = Schema {query = queryType, mutation = Nothing}
schema = Schema
{ query = queryType
, mutation = Nothing
, subscription = Just subscriptionType
}
queryType :: Out.ObjectType Identity
queryType = Out.ObjectType "Query" Nothing []
@ -45,33 +54,66 @@ philosopherType = Out.ObjectType "Philosopher" Nothing []
= Out.Field Nothing (Out.NonNullScalarType string) HashMap.empty
lastNameResolver = pure $ Type.String "Nietzsche"
subscriptionType :: Out.ObjectType Identity
subscriptionType = Out.ObjectType "Subscription" Nothing []
$ HashMap.singleton "newQuote"
$ EventStreamResolver quoteField (pure $ Type.Object mempty)
$ pure $ yield $ Type.Object mempty
where
quoteField =
Out.Field Nothing (Out.NonNullObjectType quoteType) HashMap.empty
quoteType :: Out.ObjectType Identity
quoteType = Out.ObjectType "Quote" Nothing []
$ HashMap.singleton "quote"
$ ValueResolver quoteField
$ pure "Naturam expelles furca, tamen usque recurret."
where
quoteField =
Out.Field Nothing (Out.NonNullScalarType string) HashMap.empty
spec :: Spec
spec =
describe "execute" $ do
it "skips unknown fields" $
let data'' = Aeson.object
[ "philosopher" .= Aeson.object
[ "firstName" .= ("Friedrich" :: String)
context "Query" $ do
it "skips unknown fields" $
let data'' = Aeson.object
[ "philosopher" .= Aeson.object
[ "firstName" .= ("Friedrich" :: String)
]
]
]
expected = Response data'' mempty
execute' = execute schema Nothing (mempty :: HashMap Name Aeson.Value)
actual = fromRight (singleError "")
$ runIdentity
$ either (pure . parseError) execute'
$ parse document "" "{ philosopher { firstName surname } }"
in actual `shouldBe` expected
it "merges selections" $
let data'' = Aeson.object
[ "philosopher" .= Aeson.object
[ "firstName" .= ("Friedrich" :: String)
, "lastName" .= ("Nietzsche" :: String)
expected = Response data'' mempty
execute' = execute schema Nothing (mempty :: HashMap Name Aeson.Value)
actual = fromRight (singleError "")
$ runIdentity
$ either (pure . parseError) execute'
$ parse document "" "{ philosopher { firstName surname } }"
in actual `shouldBe` expected
it "merges selections" $
let data'' = Aeson.object
[ "philosopher" .= Aeson.object
[ "firstName" .= ("Friedrich" :: String)
, "lastName" .= ("Nietzsche" :: String)
]
]
]
expected = Response data'' mempty
execute' = execute schema Nothing (mempty :: HashMap Name Aeson.Value)
actual = fromRight (singleError "")
$ runIdentity
$ either (pure . parseError) execute'
$ parse document "" "{ philosopher { firstName } philosopher { lastName } }"
in actual `shouldBe` expected
expected = Response data'' mempty
execute' = execute schema Nothing (mempty :: HashMap Name Aeson.Value)
actual = fromRight (singleError "")
$ runIdentity
$ either (pure . parseError) execute'
$ parse document "" "{ philosopher { firstName } philosopher { lastName } }"
in actual `shouldBe` expected
context "Subscription" $
it "subscribes" $
let data'' = Aeson.object
[ "newQuote" .= Aeson.object
[ "quote" .= ("Naturam expelles furca, tamen usque recurret." :: String)
]
]
expected = Response data'' mempty
execute' = execute schema Nothing (mempty :: HashMap Name Aeson.Value)
Left stream = runIdentity
$ either (pure . parseError) execute'
$ parse document "" "subscription { newQuote { quote } }"
Just actual = runConduitPure $ stream .| await
in actual `shouldBe` expected

7
tests/Test/DirectiveSpec.hs
View File

@ -1,3 +1,7 @@
{- This Source Code Form is subject to the terms of the Mozilla Public License,
v. 2.0. If a copy of the MPL was not distributed with this file, You can
obtain one at https://mozilla.org/MPL/2.0/. -}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE QuasiQuotes #-}
module Test.DirectiveSpec
@ -14,7 +18,8 @@ import Test.Hspec (Spec, describe, it, shouldBe)
import Text.RawString.QQ (r)
experimentalResolver :: Schema IO
experimentalResolver = Schema { query = queryType, mutation = Nothing }
experimentalResolver = Schema
{ query = queryType, mutation = Nothing, subscription = Nothing }
where
queryType = Out.ObjectType "Query" Nothing []
$ HashMap.singleton "experimentalField"

6
tests/Test/FragmentSpec.hs
View File

@ -1,3 +1,7 @@
{- This Source Code Form is subject to the terms of the Mozilla Public License,
v. 2.0. If a copy of the MPL was not distributed with this file, You can
obtain one at https://mozilla.org/MPL/2.0/. -}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE QuasiQuotes #-}
module Test.FragmentSpec
@ -76,7 +80,7 @@ sizeFieldType
toSchema :: Text -> (Text, Value) -> Schema IO
toSchema t (_, resolve) = Schema
{ query = queryType, mutation = Nothing }
{ query = queryType, mutation = Nothing, subscription = Nothing }
where
unionMember = if t == "Hat" then hatType else shirtType
typeNameField = Out.Field Nothing (Out.NamedScalarType string) mempty

10
tests/Test/RootOperationSpec.hs
View File

@ -1,3 +1,7 @@
{- This Source Code Form is subject to the terms of the Mozilla Public License,
v. 2.0. If a copy of the MPL was not distributed with this file, You can
obtain one at https://mozilla.org/MPL/2.0/. -}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE QuasiQuotes #-}
module Test.RootOperationSpec
@ -20,8 +24,10 @@ hatType = Out.ObjectType "Hat" Nothing []
schema :: Schema IO
schema = Schema
(Out.ObjectType "Query" Nothing [] hatFieldResolver)
(Just $ Out.ObjectType "Mutation" Nothing [] incrementFieldResolver)
{ query = Out.ObjectType "Query" Nothing [] hatFieldResolver
, mutation = Just $ Out.ObjectType "Mutation" Nothing [] incrementFieldResolver
, subscription = Nothing
}
where
garment = pure $ Object $ HashMap.fromList
[ ("circumference", Int 60)

6
tests/Test/StarWars/Schema.hs
View File

@ -20,7 +20,11 @@ import Prelude hiding (id)
-- See https://github.com/graphql/graphql-js/blob/master/src/__tests__/starWarsSchema.js
schema :: Schema Identity
schema = Schema { query = queryType, mutation = Nothing }
schema = Schema
{ query = queryType
, mutation = Nothing
, subscription = Nothing
}
where
queryType = Out.ObjectType "Query" Nothing [] $ HashMap.fromList
[ ("hero", heroFieldResolver)