RESTful service empty response

Question

I have problem with REST service I'm trying to make. I use GlassFish 4.1 and Jersay 2.1 which is built-in.

@Path("/driver")
@RequestScoped
public class DriverResource {
    private static Logger logger = LogManager.getLogger(DriverResource.class);

        @Inject
        private DriverManager driverManager;

        private SharedResponseFactory responseFactory = new SharedResponseFactory();

        @GET
        @Path("/login/{pesel}/{password}")
        @Produces("application/json")
        public Response logIn(@PathParam("pesel") String pesel, @PathParam("password") String password) {
            try {
                Driver driver = driverManager.logIn(pesel, password);

                logger.debug("Zalogowano kierowcę: " + driver.getFullName());
                return responseFactory.getSuccesResponse(driver);
            } catch (ErrorDAOException e) {
                logger.catching(e);
                return responseFactory.getFailureResponse(e);
            } catch (NoDataFoundDAOException e) {
                logger.catching(e);
                return responseFactory.getFailureResponse(e);
            } catch (Exception e) {
                logger.catching(e);
                return responseFactory.getFailureResponse(e);
            }
        }
    }

When I'm trying to return my Entity I get response like this:

{}

In my Entities there are many cyclic references and I don't operate on actual implementation but interfaces. I need to make it the way Retrofit in my Android application could deserialize it.

Glassfish's logs are empty, there are no errors related to rest. I have no idea how to make it working.

I tried to use @JsonIdentityInfo to handle cyclic references and @JsonTypeInfo to make interfaces possible to desserialize.

I think there's a small trick that will make it working but unfortunately I don't know it...

Answer 1

I found a relatively easy way to test for cyclic references. If you use JAXB (which is included with glassfish), you can try marshalling your entity to XML. A JAXBException is thrown if any cyclic references are found.

Here is a method to marshall an object to XML:

public static <T> String marshalToXml(T instance) throws javax.xml.bind.JAXBException {
    JAXBContext jaxbContext = JAXBContext.newInstance(instance.getClass());
    Marshaller jaxbMarshaller = jaxbContext.createMarshaller();
    jaxbMarshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
    StringWriter writer = new StringWriter();
    jaxbMarshaller.marshal(instance, writer);
    return writer.toString();
}

and the service can test the object like this:

@Path("/driver")
@RequestScoped
public class DriverResource {

    private static Logger logger = LogManager.getLogger(DriverResource.class);

    @Inject
    private DriverManager driverManager;

    private SharedResponseFactory responseFactory = new SharedResponseFactory();

    @GET
    @Path("/login/{pesel}/{password}")
    @Produces("application/json")
    public Response logIn(@PathParam("pesel") String pesel, @PathParam("password") String password) {
        try {
            Driver driver = driverManager.logIn(pesel, password);

            marshalToXml(driver); //remember to import static method

            logger.debug("Zalogowano kierowcę: " + driver.getFullName());
            return responseFactory.getSuccesResponse(driver);
        } catch (ErrorDAOException e) {
            logger.catching(e);
            return responseFactory.getFailureResponse(e);
        } catch (NoDataFoundDAOException e) {
            logger.catching(e);
            return responseFactory.getFailureResponse(e);
        } catch (JAXBException e) {
            //view error message to see cyclic reference
            logger.catching(e);
            return responseFactory.getFailureResponse(e);
        } catch (Exception e) {
            logger.catching(e);
            return responseFactory.getFailureResponse(e);
        }
    }
}