Hi <@UGUMP8USE> does graphql kotlin spring server ...

# graphql-kotlin

[Ferranostra]

Hi @Dariusz Kuc does graphql kotlin spring server support injection of graphql context into any spring service ?

Is it possible to put the value into a webflux context in webflux webfilter and retrieve it in spring service? Eventually webflux context got cleared before graphql mutation and query.

With respect.

[Dariusz Kuc]

👋 graphql-kotlin supports automatic context propagation since v6 (see https://github.com/ExpediaGroup/graphql-kotlin/releases/tag/6.0.0) so if you add something to the Reactor context in the WebFilter, it will be accessible from the GraphQL context.

GraphQL context is not a Spring bean so it cannot be autowired but you can access it through DataFetchingEnvironment - see https://opensource.expediagroup.com/graphql-kotlin/docs/schema-generator/execution/contextual-data#graphql-context-map

[Ferranostra]

Thank you for your response.

But am I able to set something in

org.springframework.web.server.WebFilter

and reuse it in any place like

Mono.deferContextual(...)?

Use case is that I have to read header parameters and put it inside webclient’s header.
Graphql context looks overloaded. I can put it only on Mutation/Query level and then send in each function as a parameter which is not the best way.

[Dariusz Kuc]

As long as you are running coroutines then yes it should have access to the reactor context (due to reactor <-> coroutine interop)

[Ferranostra]

But I have an empty context in mutation unfortunately

[Ferranostra]

Draft code for filter

[Ferranostra]

@Component
class UserWebFilter : WebFilter {

    override fun filter(serverWebExchange: ServerWebExchange, webFilterChain: WebFilterChain): Mono<Void> =
        webFilterChain
            .filter(serverWebExchange)
            .contextWrite {
                context(it, serverWebExchange)
            }.then()

    private fun context(
        it: Context,
        serverWebExchange: ServerWebExchange
    ): Context {
        val context = putHeaderToContext(
            putHeaderToContext(it, serverWebExchange, X_USER_ID, UUID::fromString),
            serverWebExchange,
            AUTHORIZATION
        ) { a -> a!! }
        return context
    }

    private fun getHeader(serverWebExchange: ServerWebExchange, headerName: String) =
        serverWebExchange
            .request
            .headers
            .getFirst(headerName)

    private fun putHeaderToContext(
        context: Context,
        serverWebExchange: ServerWebExchange,
        headerName: String,
        transformFunction: Function<String?, Any>
    ): Context {
        val headerValue: String? = getHeader(serverWebExchange, headerName)
        return if (ObjectUtils.isNotEmpty(headerValue))
            context.put(
                headerName,
                transformFunction.apply(headerValue)
            ) else context
//                throw ForbiddenRequestException(MISSED_REQUIRED_HEADER_PARAMETERS)
    }
}

[Dariusz Kuc]

Make sure you are using v6+

[Ferranostra]

<graphql-kotlin-spring-server.version>6.3.0</graphql-kotlin-spring-server.version>

[Ferranostra]

and for the query

[Dariusz Kuc]

See some discussions/issues on the repo that talk about auth

[Dariusz Kuc]

There is some example code there

[Ferranostra]

@Component
class BoardQuery(
    private val boardService: BoardService
) : Query {

    fun getBoardFull(
        id: UUID
    ) = Mono.deferContextual { c -> boardService.getBoard(id, c)}

context under deferCotextual is empty

[Ferranostra]

I’ve found examples with the following

@Component
class ContextualQuery : Query {

    @GraphQLDescription("query that uses GraphQLContext context")
    fun contextualQuery(
        @GraphQLDescription("some value that will be returned to the user")
        value: Int,
        env: DataFetchingEnvironment
    ): ContextualResponse = ContextualResponse(value, env.graphQlContext.getOrDefault("myCustomValue", "defaultValue"))
}

[Ferranostra]

The key difference is that I have to use Webflux Context instead of DataFetchingEnvironment

[Ferranostra]

🤔

[Ferranostra]

@Dariusz Kuc please help.

[Dariusz Kuc]

as I wrote above ->

As long as you are running coroutines then yes it should have access to the reactor context (due to reactor <-> coroutine interop)

Default data fetcher logic runs the coroutines in the original scope (https://github.com/ExpediaGroup/graphql-kotlin/blob/master/generator/graphql-kotli[…]expediagroup/graphql/generator/execution/FunctionDataFetcher.kt).

Your method (fun getBoardFull ) is NOT a coroutine hence it won't get the context set. You will either have to use custom data fetcher that wraps up the Mono execution OR switch to coroutines.

[Dariusz Kuc]

injection of DataFetchingEnvironment is automatic for both coroutine and regular functions

[Ferranostra]

Now it's clear thanks. I'll try to apply your comments. Appreciate your support.

[Ferranostra]

Let me post here how I’ve resolved it

import com.expediagroup.graphql.server.spring.execution.SpringDataFetcher
...

/**
 * Custom function data fetcher that adds support for Reactor Mono.
 */
class CustomFunctionDataFetcher(
    target: Any?,
    fn: KFunction<*>,
    appContext: ApplicationContext
) : SpringDataFetcher(target, fn, appContext) {

    override fun get(environment: DataFetchingEnvironment): Any? {
        val context = environment.getContext<GraphQLRequestContext>()
        return when (val result = super.get(environment)) {
            is Mono<*> -> result.contextWrite { c ->
                c.put(X_USER_ID, context.xUserId)
                    .put(AUTHORIZATION, context.authorization)
            }.toFuture()

            else -> result
        }
    }
}

[Ferranostra]

Thanks to @Dariusz Kuc for support. 🙏