Unable to map / fetch the response entity on 422 error code in Microprofile Rest Client

Question

I have an API, when I call it through postman it gives the below response on the following cases:

Case1: status code: 200

{"success": "student record is present",
  "error": null}

Case2: status code: 422

{"success": null,
  "error": "studentname should not contain numerics"}

I want to achieve the same above results of two case through microprofile restclient using quarkus/java project. So created the below classes

Java DTO Class:

public class StudentResponse{

    private String success;

    private String error;

    public String getSuccess() {
        return success;
    }

    public void setSuccess(String success) {
        this.success = success;
    }

    public String getError() {
        return error;
    }

    public void setError(String error) {
        this.error = error;
    }

    @Override
    public String toString() {
        return "StudentResponse [success=" + success + ", error=" + error + "]";
    }

}

Rest-Client Class:

package com.tatadigital.rest.service;

@RegisterRestClient(configKey = "student-client-api")
@Consumes(MediaType.APPLICATION_JSON)
@Produces(MediaType.APPLICATION_JSON)
public interface StudentService {

    @POST
    @Path("/checkStudent")
    StudentResponse checkStudent(@RequestBody StudentCheck studentCheck);
}

Finally, I tested it through the app, and for case-1, receiving the response body with status code 200 as expected. But for case-2 as the status code is 422 the exception is thrown and getting handled but in the exception object we have response object and inside it we have response entity. This response entity is null and even studentResponse is also null. I want to get the error message(json response) in 422 status code case with microprofile rest client case. Any approach/suggestion to achieve this?

Answer 1

Unfortunately this isn't something supported by the Microprofile client. However this sounds like a useful feature, so do you mind opening an issue in the Quarkus issue tracker?

Answer 2

Edit

You can also achieve the same behavior from the DefaultResponseExceptionMapper by adding
resteasy.original.webapplicationexception.behavior=true
in the application.properties.

When this option is false, the DefaultResponseExceptionMapper wraps the WebApplicationException and returns an exception according to the HTTP status code, for example

} else if (e instanceof BadRequestException) {
    return new ResteasyBadRequestException((BadRequestException)e);
}

which doesn't contain the entity from the response.

If you enable the original behavior, the exception is returned as is and the response entity is available for you to read it.

wae.getResponse().readEntity(StudentResponse.class);

---

In case of a status code >=400 a WebApplicationException is thrown that holds a Response object, but is handled by the DefaultResponseExceptionMapper.

Create a custom exception mapper and throw a WebApplicationException that contains only the response

public class HttpExceptionMapper implements ResponseExceptionMapper<Throwable> {

    @Override
    public Throwable toThrowable(Response response) {
        throw new WebApplicationException(response);
    }

}

Register the mapper to your rest client with the appropriate annotation @RegisterProvider(HttpExceptionMapper.class)

and you will be able to read the entity in the response

StudentResponse studentResponse;
try {
  studentResponse = checkStudent(studentCheck);
} catch(WebApplicationException wae) {
  studentResponse = wae.getResponse().readEntity(StudentResponse.class);
}