|
1 | | ---- |
2 | | -id: async-models |
3 | | -title: Async Models |
4 | | ---- |
5 | | -By default, `graphql-kotlin-schema-generator` will resolve all functions synchronously, i.e. it will block the |
6 | | -underlying thread while executing the target function. While you could configure your GraphQL server with execution |
7 | | -strategies that execute each query in parallel on some thread pools, instead we highly recommend to utilize asynchronous |
8 | | -programming models. |
9 | | - |
10 | | -## Coroutines |
11 | | - |
12 | | -`graphql-kotlin-schema-generator` has built-in support for Kotlin coroutines. Provided default |
13 | | -[FunctionDataFetcher](https://github.com/ExpediaDotCom/graphql-kotlin/blob/master/graphql-kotlin-schema-generator/src/main/kotlin/com/expedia/graphql/execution/FunctionDataFetcher.kt) |
14 | | -will automatically asynchronously execute suspendable functions and convert the result to `CompletableFuture` expected |
15 | | -by `graphql-java`. |
16 | | - |
17 | | -Example |
18 | | - |
19 | | -```kotlin |
20 | | -data class User(val id: String, val name: String) |
21 | | - |
22 | | -class Query { |
23 | | - suspend fun getUser(id: String): User { |
24 | | - // Your coroutine logic to get user data |
25 | | - } |
26 | | -} |
27 | | -``` |
28 | | - |
29 | | -will produce the following schema |
30 | | - |
31 | | -```graphql |
32 | | - |
33 | | -schema { |
34 | | - query: Query |
35 | | -} |
36 | | - |
37 | | -type Query { |
38 | | - getUser(id: String!): User |
39 | | -} |
40 | | - |
41 | | -type User { |
42 | | - id: String! |
43 | | - name: String! |
44 | | -} |
45 | | -``` |
46 | | - |
47 | | -## CompletableFuture |
48 | | - |
49 | | -`graphql-java` relies on Java `CompletableFuture` for asynchronously processing the requests. In order to simplify the |
50 | | -interop with `graphql-java`, `graphql-kotlin-schema-generator` has a built-in hook which will automatically unwrap a |
51 | | -`CompletableFuture` and use the inner class as the return type in the schema. |
52 | | - |
53 | | -```kotlin |
54 | | -data class User(val id: String, val name: String) |
55 | | - |
56 | | -class Query { |
57 | | - fun getUser(id: String): CompletableFuture<User> { |
58 | | - // Your logic to get data asynchronously |
59 | | - } |
60 | | -} |
61 | | -``` |
62 | | - |
63 | | -will result in the exactly the same schema as in the coroutine example above. |
64 | | - |
65 | | -## RxJava/Reactor |
66 | | - |
67 | | -If you use a different monad type, like `Single` from [RxJava](https://github.com/ReactiveX/RxJava) or `Mono` from |
68 | | -[Project Reactor](https://projectreactor.io/), you just have to provide the logic in |
69 | | -`SchemaGeneratorHooks.willResolveMonad` to unwrap it and return the inner class. |
70 | | - |
71 | | -```kotlin |
72 | | -class RxJava2Query { |
73 | | - fun asynchronouslyDo(): Observable<Int> = Observable.just(1) |
74 | | - |
75 | | - fun asynchronouslyDoSingle(): Single<Int> = Single.just(1) |
76 | | - |
77 | | - fun maybe(): Maybe<Int> = Maybe.empty() |
78 | | -} |
79 | | - |
80 | | -private class MonadHooks : SchemaGeneratorHooks { |
81 | | - override fun willResolveMonad(type: KType): KType = when (type.classifier) { |
82 | | - Observable::class, Single::class, Maybe::class -> type.arguments.firstOrNull()?.type |
83 | | - else -> type |
84 | | - } ?: type |
85 | | -} |
86 | | - |
87 | | -val configWithRxJavaMonads = getConfig(hooks = MonadHooks()) |
88 | | - |
89 | | -toSchema(queries = listOf(TopLevelObject(RxJava2Query())), config = configWithRxJavaMonads) |
90 | | -``` |
91 | | - |
92 | | -This will produce |
93 | | - |
94 | | -```graphql |
95 | | -type Query { |
96 | | - asynchronouslyDo(): Int |
97 | | - asynchronouslyDoSingle(): Int |
98 | | - maybe: Int |
99 | | -} |
100 | | -``` |
101 | | - |
102 | | -You can find additional example on how to configure the hooks in our [unit |
103 | | -tests](https://github.com/ExpediaGroup/graphql-kotlin/blob/master/graphql-kotlin-schema-generator/src/test/kotlin/com/expediagroup/graphql/generator/SchemaGeneratorAsyncTests.kt). |
| 1 | +--- |
| 2 | +id: async-models |
| 3 | +title: Async Models |
| 4 | +--- |
| 5 | +By default, `graphql-kotlin-schema-generator` will resolve all functions synchronously, i.e. it will block the |
| 6 | +underlying thread while executing the target function. While you could configure your GraphQL server with execution |
| 7 | +strategies that execute each query in parallel on some thread pools, instead we highly recommend to utilize asynchronous |
| 8 | +programming models. |
| 9 | + |
| 10 | +## Coroutines |
| 11 | + |
| 12 | +`graphql-kotlin-schema-generator` has built-in support for Kotlin coroutines. Provided default |
| 13 | +[FunctionDataFetcher](https://github.com/ExpediaDotCom/graphql-kotlin/blob/master/graphql-kotlin-schema-generator/src/main/kotlin/com/expedia/graphql/execution/FunctionDataFetcher.kt) |
| 14 | +will automatically asynchronously execute suspendable functions and convert the result to `CompletableFuture` expected |
| 15 | +by `graphql-java`. |
| 16 | + |
| 17 | +Example |
| 18 | + |
| 19 | +```kotlin |
| 20 | +data class User(val id: String, val name: String) |
| 21 | + |
| 22 | +class Query { |
| 23 | + suspend fun getUser(id: String): User { |
| 24 | + // Your coroutine logic to get user data |
| 25 | + } |
| 26 | +} |
| 27 | +``` |
| 28 | + |
| 29 | +will produce the following schema |
| 30 | + |
| 31 | +```graphql |
| 32 | + |
| 33 | +schema { |
| 34 | + query: Query |
| 35 | +} |
| 36 | + |
| 37 | +type Query { |
| 38 | + getUser(id: String!): User |
| 39 | +} |
| 40 | + |
| 41 | +type User { |
| 42 | + id: String! |
| 43 | + name: String! |
| 44 | +} |
| 45 | +``` |
| 46 | + |
| 47 | +## CompletableFuture |
| 48 | + |
| 49 | +`graphql-java` relies on Java `CompletableFuture` for asynchronously processing the requests. In order to simplify the |
| 50 | +interop with `graphql-java`, `graphql-kotlin-schema-generator` has a built-in hook which will automatically unwrap a |
| 51 | +`CompletableFuture` and use the inner class as the return type in the schema. |
| 52 | + |
| 53 | +```kotlin |
| 54 | +data class User(val id: String, val name: String) |
| 55 | + |
| 56 | +class Query { |
| 57 | + fun getUser(id: String): CompletableFuture<User> { |
| 58 | + // Your logic to get data asynchronously |
| 59 | + } |
| 60 | +} |
| 61 | +``` |
| 62 | + |
| 63 | +will result in the exactly the same schema as in the coroutine example above. |
| 64 | + |
| 65 | +## RxJava/Reactor |
| 66 | + |
| 67 | +If you want to use a different monad type, like `Single` from [RxJava](https://github.com/ReactiveX/RxJava) or `Mono` from |
| 68 | +[Project Reactor](https://projectreactor.io/), you have to: |
| 69 | + |
| 70 | +1. Create custom `SchemaGeneratorHook` that implements `willResolveMonad` to provide the necessary logic |
| 71 | +to correctly unwrap the monad and return the inner class to generate valid schema |
| 72 | + |
| 73 | +```kotlin |
| 74 | +class MonadHooks : SchemaGeneratorHooks { |
| 75 | + override fun willResolveMonad(type: KType): KType = when (type.classifier) { |
| 76 | + Mono::class -> type.arguments.firstOrNull()?.type |
| 77 | + else -> type |
| 78 | + } ?: type |
| 79 | +} |
| 80 | +``` |
| 81 | + |
| 82 | +2. Provide custom data fetcher that will properly process those monad types. |
| 83 | + |
| 84 | +```kotlin |
| 85 | +class CustomFunctionDataFetcher(target: Any?, fn: KFunction<*>, objectMapper: ObjectMapper) : FunctionDataFetcher(target, fn, objectMapper) { |
| 86 | + override fun get(environment: DataFetchingEnvironment): Any? = when (val result = super.get(environment)) { |
| 87 | + is Mono<*> -> result.toFuture() |
| 88 | + else -> result |
| 89 | + } |
| 90 | +} |
| 91 | + |
| 92 | +class CustomDataFetcherFactoryProvider( |
| 93 | + private val objectMapper: ObjectMapper |
| 94 | +) : SimpleKotlinDataFetcherFactoryProvider(objectMapper) { |
| 95 | + |
| 96 | + override fun functionDataFetcherFactory(target: Any?, kFunction: KFunction<*>): DataFetcherFactory<Any> = DataFetcherFactory<Any> { |
| 97 | + CustomFunctionDataFetcher( |
| 98 | + target = target, |
| 99 | + fn = kFunction, |
| 100 | + objectMapper = objectMapper) |
| 101 | + } |
| 102 | +} |
| 103 | +``` |
| 104 | + |
| 105 | +With the above you can then create your schema as follows: |
| 106 | + |
| 107 | +```kotlin |
| 108 | +class ReactorQuery { |
| 109 | + fun asynchronouslyDo(): Mono<Int> = Mono.just(1) |
| 110 | +} |
| 111 | + |
| 112 | +val configWithReactorMonoMonad = SchemaGeneratorConfig( |
| 113 | + supportedPackages = listOf("myPackage"), |
| 114 | + hooks = MonadHooks(), |
| 115 | + dataFetcherFactoryProvider = CustomDataFetcherFactoryProvider()) |
| 116 | + |
| 117 | +toSchema(queries = listOf(TopLevelObject(ReactorQuery())), config = configWithReactorMonoMonad) |
| 118 | +``` |
| 119 | + |
| 120 | +This will produce |
| 121 | + |
| 122 | +```graphql |
| 123 | +type Query { |
| 124 | + asynchronouslyDo(): Int |
| 125 | +} |
| 126 | +``` |
| 127 | + |
| 128 | +You can find additional example on how to configure the hooks in our [unit |
| 129 | +tests](https://github.com/ExpediaGroup/graphql-kotlin/blob/master/graphql-kotlin-schema-generator/src/test/kotlin/com/expediagroup/graphql/generator/SchemaGeneratorAsyncTests.kt) |
| 130 | +and [example app](https://github.com/ExpediaGroup/graphql-kotlin/blob/master/examples/spring/src/main/kotlin/com/expediagroup/graphql/examples/query/AsyncQuery.kt). |
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