OpenFeign/feign

feign-kotlin: Decoder type returns "Object" when method is suspending

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Aperta il 23 apr 2023

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 (6 commenti) (1 reazione) (0 assegnatari)Java (9070 star) (1911 fork)batch import
help wantedkotlinneeds info

Descrizione

Currently using feign-kotlin 12.3 and kotlin 1.8.10 while attempting to use a custom decoder. When my method in the the TestClient is suspending type is printed out as "java.lang.Object" however, when not using suspend it returns the proper type of TestObject. This is currently preventing me from being able to get the proper serializer

Client Snippet:

public interface TestClient  {
    @RequestLine("GET /{uuid}")
    public suspend fun testGet(@Param("uuid") uuid: UUID): TestObject
}

Decoder snippet:

public class CustomDecoder: Decoder {
    override fun decode(response: Response, type: Type): Any? {
        if (response.status() != 404 && response.status() != 204) {
                ...
                println(type)
               ...
            }
        } else {
           ...
        }
    }
}

Guida contributor

Tech stack
kotlinjava
Dominio
backendapi
Tipo issue
bug
DifficoltàQuanto dovrebbe essere impegnativa per un nuovo contributor.
3
Tempo stimatoTempo stimato per completare e verificare uno scope piccolo.
half day
Stato attivitàQuanto è probabile che la issue sia ancora attiva e reviewable.
stale
ChiarezzaQuanto chiaramente la issue descrive problema, scope e risultato atteso.
mostly clear
Prerequisiti
Kotlin coroutinesFeign basicsCustom decoder usage
Adatta ai principiantiQuanto la issue è adatta a contributor alla prima esperienza.
40
Direzione di ricerca
Investigate how Feign resolves the return type for suspend functions in the feign kotlin module. The issue likely stems from the method handler not converting the Continuation generic type to the actual response type. Look at KotlinReflective.FeignInvocationHandler or the DefaultDecoder to see how non suspend methods retrieve Type. Compare with suspend function handling in the same codebase. Consider checking the Kotlin coroutines reflection API to extract the underlying return type.