hello! does anyone know what is the proper way to ...

# spring

[Dariusz Kuc]

hello! does anyone know what is the proper way to invoke coroutines from Spring WebFilters? e.g. something like this works and populates the context as expected

class FooFilter : WebFilter {
    override fun filter(exchange: ServerWebExchange, chain: WebFilterChain): Mono<Void> = mono {
        foo()
    }.flatMap { foo ->
        chain.filter(exchange).subscriberContext { it.put("foo", foo) }
    }
    
    suspend fun foo(): Foo { ... }
}

[Dariusz Kuc]

problem arise if there is another webfilter populates subscriber context BEFORE this filter and we would like to also access it in foo()

[Dariusz Kuc]

with latest spring boot and coroutines we do have a nice interop between them, e.g. we can access reactor context from coroutine context

val bar = coroutineContext[ReactorContext]?.context?.get<Bar>("bar")

[Dariusz Kuc]

but in the example above, when executing FooFilter our reactor context is empty

[Dariusz Kuc]

any ideas/suggestions?

[Dariusz Kuc]

so doing it like this

Mono.subscriberContext()
    .flatMap { ctx ->
        val foo = runBlocking(ctx.asCoroutineContext()) {
          foo()
        }
        chain.filter(exchange).subscriberContext { it.put("foo", foo) }
    }

seems to work... but that runBlocking there seems just wrong

[Dariusz Kuc]

... weird... original one using mono { foo() } started working for me

[Dariusz Kuc]

nvm