Vert.x 4 Serialization error (Native mode)

[pjgg]

Describe the bug

Quarkus: 2.X Native mode.

I am working in a Vert.x application over Quarkus 2.x and I am getting the following error when I am trying to encode a io.vertx.ext.auth.User into a Json String through this method Json.encode(user) (Note that the user is empty).

Error:

Failed to encode as JSON: No serializer found for class io.vertx.ext.auth.impl.UserImpl and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS)"

I have tried to register an auth "user", for reflection through a reflection-config.json file or by a @RegisterForReflection(targets = {User.class, UserImpl.class}) annotation without success.

For example:

package io.quarkus.qe.vertx.web.auth;

import io.quarkus.runtime.annotations.RegisterForReflection;
import io.vertx.ext.auth.User;
import io.vertx.ext.auth.impl.UserImpl;

@RegisterForReflection(targets = {User.class, UserImpl.class})
public class MyReflectionConfiguration {
}

In the end following the error recommendation we have created a custom object mapper used by Vertx Json.encode library.

@Singleton
public class VertxAuthObjectMapperCustomizer implements ObjectMapperCustomizer {

    @Override
    public void customize(ObjectMapper objectMapper) {
        objectMapper.configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false);
    }
}

You have a reproducer in this project over this module. You could clone the project, remove the class io.quarkus.qe.vertx.web.config.VertxAuthObjectMapperCustomizer and run the following command: mvn clean install -pl 302-quarkus-vertx-jwt -P native

Another way to reproduce the issue is just to create a simple Vertx app for example with Reactive-routes:

Dependencies:

 <dependency>
            <groupId>io.quarkus</groupId>
            <artifactId>quarkus-vertx-web</artifactId>
        </dependency>

        <dependency>
            <groupId>io.vertx</groupId>
            <artifactId>vertx-auth-jwt</artifactId>
        </dependency>

And then create the following endpoint:

@RouteBase(path = "/test")
public class TestRouteHandler {
   
    @Route(methods = HttpMethod.GET, path = "/hello")
    Uni<String> hello() {
        User user = new UserImpl();
        System.out.println(Json.encode(user));
        return Uni.createFrom().item("hello");
    }
}

Make a native compilation and then make a request to http://localhost:8080/test/hello/

Or even forget about io.vertx:vertx-auth-jwt

IF you have a "RandomObject" like

@RegisterForReflection
public class RandomObject {
}

And then you try to serialize as a Json, is going to fail (native mode):

@RouteBase(path = "/test")
public class TestRouteHandler {

    @Route(methods = HttpMethod.GET, path = "/hello")
    Uni<String> hello() {
        RandomObject random = new RandomObject();
        System.out.println(Json.encode(random));
        return Uni.createFrom().item("hello");
    }
}

Query: curl -v http://localhost:8080/test/hello/
Result:

 io.vertx.core.json.EncodeException: Failed to encode as JSON: No serializer found for class io.quarkus.qe.RandomObject and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS)

[cescoffier]

Yes, this case cannot be easily tracked.
Note that it should work if you return a Uni<RandomObject> directly.

[cescoffier]

BTW, was it working with the 1.x version?

[NinjaTycoon]

I had an issue with a 3rd party library I created that uses gson. To my surprise, gson itself basically works without a problem in the native, barring the fact that the objects were incorrectly empty. but, it was only when I saw this syntax above that I discovered how to annotate 3rd party library classes inside the main project:

@RegisterForReflection(targets = {User.class, UserImpl.class})

Where User and UserImpl could be in a utility jar.

Sort of off topic, but just wanted a quick way to suggest that the documentation have this added in various locations as I read a ton of documentation yet never saw this usage. Only here in this Issue did I discover it. Saved the day!!! Thanks!