How to return Response with message, jax rs

Question

I have a web service rest using jax-rs, my service return a List of objects but y don't know how to add custom status values to response, for example the result that I want to build is the following:

If its ok:

{
   "status": "success",
   "message": "list ok!!",
   "clients": [{
        "name": "john",
        "age": 23
    },
    {
        "name": "john",
        "age": 23
    }]
}

If is error:

{
   "status": "error",
   "message": "not found records",
   "clients": []
}

my rest service:

 @POST
 @Path("/getById")
 @Consumes(MediaType.APPLICATION_JSON)
 @Produces(MediaType.APPLICATION_JSON)
 public List<Client> getById(Client id) {

  try {

       return Response.Ok(new ClientLogic().getById(id)).build();
       //how to add status = success, and message = list! ?

    } catch (Exception ex) {
       return  ??   
       // ex.getMessage() = "not found records"
       //i want return json with satus = error and message from exception
    }
    } 

Answer 1

If you want full control on your output JSON structure, use a JsonObjectBuilder (as explained here, then convert your final json to String and write (for example for the success json):

return Response.Ok(jsonString,MediaType.APPLICATION_JSON).build();

and change your return value to a Response object.

However please note that you are trying to send redundant (and not standard) piece of information, which is already encoded into the HTTP error codes. When you use Response.Ok, the response will have code "200 OK", and you can study the Response class methods for returning any HTTP code you desire. In your case it would be:

return Response.status(Response.Status.NOT_FOUND).entity(ex.getMessage()).build();

returning a 404 HTTP code (look at Response.Status list of codes).

Answer 2

I was facing the same problem and here is how I solved it. If your service method succeeds, return Response with status 200 and with your desired entities. If your service method throws an exception, return Response with different status and with exception message bind to your RestError class.

@POST
@Path("/getById")
@Consumes(MediaType.APPLICATION_JSON)
@Produces(MediaType.APPLICATION_JSON)
public Response getById(Client id) {
  try {    
    return Response.Ok(new ClientLogic().getById(id)).build();
  } catch (Exception ex) {
    return Response.status(201) // 200 means OK, I want something different
                   .entity(new RestError(status, msg))
                   .build();   
  }
}

In client, I am using these utility methods to read entity from Response. If there is an error, I throw an exception containing status and msg of that error.

public class ResponseUtils {

  public static <T> T convertToEntity(Response response, 
                                      Class<T> target)
                          throws RestResponseException {
    if (response.getStatus() == 200) {
      return response.readEntity(target);
    } else {
      RestError err = response.readEntity(RestError.class);
      // my exception class
      throw new RestResponseException(err);
    }
  }

  // this method is for reading Set<> and List<> from Response
  public static <T> T convertToGenericType(Response response,
                                           GenericType<T> target)
                          throws RestResponseException {
    if (response.getStatus() == 200) {
      return response.readEntity(target);
    } else {
      RestDTOError err = response.readEntity(RestError.class);
      // my exception class
      throw new RestResponseException(err);
    }
  }

}

My client method will call (through proxy object) service method

public List<Client> getById(Client id) 
                        throws RestResponseException {
  return ResponseUtils.convertToGenericType(getProxy().getById(id),
                                            new GenericType<List<Client>>() {});
}