I want to modify ReactorContext or the context of ...

# coroutines

[kazuki tanida]

I want to modify ReactorContext or the context of reactor after a coroutine is created.
For example, some CoroutineContext has a ReactorContext which wraps a context of reactor.
In my case the context of reactor has two key/value pairs as the following image but I want to add one more pair to the current context mutably not immutable!

[kazuki tanida]

Anyway I want to modify ReactorContext or the context of reactor directly associated with a coroutine.
Is it possible?

[Nick Zois]

Adding information to the context make it available to self and spawned coroutines. So context modifications in the children may not be available to the parent.

[Nick Zois]

I put here an issue, if you face the same let me know, I am also trying to solve it in SpringbootWorld. Well, you can add extra info to the ReactorContext, but I faced issues when I call other suspend-able methods in springboot @service, which somehow eliminates the context that I ve added. I haven’t investigated more on that, but if you are in springboot you may face similar issues. e.g. Lets say that I have a rest-controller, and I add the user id and span id in the reactor’s context, if I call a method to a service component, the context keys have erased.

[kazuki tanida]

Adding information to the context make it available to self and spawned coroutines. So context modifications in the children may not be available to the parent.

I see. That make sense. 😢

I put here an issue, if you face the same let me know, I am also trying to solve it in SpringbootWorld. Well, you can add extra info to the ReactorContext, but I faced issues when I call other suspend-able methods in springboot @service, which somehow eliminates the context that I ve added. I haven’t investigated more on that, but if you are in springboot you may face similar issues. e.g. Lets say that I have a rest-controller, and I add the user id and span id in the reactor’s context, if I call a method to a service component, the context keys have erased.

I also use Kotlin with Spring Boot (WebFlux) and in WebFilter
and I found I can add extra info to the context of Reactor which belongs to ReactorContext. (but I want to modify it after WebFilter…)

like this

@Component
class HttpRequestWebFilter : WebFilter {
    override fun filter(exchange: ServerWebExchange, chain: WebFilterChain): Mono<Void> {
        return chain.filter(exchange)
                .contextWrite { ctx ->
                    ctx.put(SomeClass::class.java, someValue)
                }
    }
}

I found it works in suspending function in some bean class.

coroutineContext[ReactorContext].context.get(SomeClass::class.java)
// will result in someValue