Status 400 and Error deserializing List of Objects. No default constructor found

问题

I have this Spring Repository:

public interface MessageRepository extends CrudRepository<MessageObject, String>{

public List<MessageObject> findByEmisorOrDestinatario(String emisor, String destinatario);
}

My DAO is:

@Entity
@Table(name = "messages")
public class MessageObject implements Serializable{

private static final long serialVersionUID = 1L;
@Id
private String id;
private String emisor;
private String destinatario;
private String mensaje;
private String tipo;
@JsonFormat(pattern="yyyy-MM-dd")
private LocalDate fecha;
private String id_housing;

public MessageObject() {

  }

Now in my Controller I want to receive the Get request and search in my DB so:

@RestController
public class Controller {

@Autowired
private MessageRepository daoMsg;

@RequestMapping(value = "/Mensajes", method = RequestMethod.GET, produces=MediaType.APPLICATION_JSON_VALUE)
public List<MessageObject> enviados (@RequestParam("mail") String mail) {
    return daoMsg.findByEmisorOrDestinatario(mail, mail);   

}

}

Now I can call the service from my client, so:

ClientConfig config = new ClientConfig();
    Client client = ClientBuilder.newClient();

    WebTarget webResource = client.target("http://localhost:8082").path("/Mensajes").queryParam(mail);
    Invocation.Builder invocationBuilder = webResource.request(MediaType.APPLICATION_JSON);
    Response respuesta = invocationBuilder.get();
    int status = respuesta.getStatus();
    System.out.println(status);
    MessageObject[] listMessages = respuesta.readEntity(MessageObject[].class);

Problems: I'm receiving a 400 status code. Also an error deserializing entityRead. Doing the request with Postman returns no errors and return the list of objects in JSON format.

StackTrace:

javax.ws.rs.ProcessingException: Error deserializing object from entity 
stream. Caused by: javax.json.bind.JsonbException: Can't create instance of 
a class: class [LMessages.MessageObject; 
No default constructor found. Caused by: java.lang.NoSuchMethodException: 
[LMessages.MessageObject;.<init>()

Question: how can I know where is my code failing? am I using the service invocation well?

Things I tried: changing Mediatype to GenericType

EDIT I tried removing the / from the path, still getting status 400

回答1:

Solved. Problem was I was using .queryparam without key-value structure. So changing .queryparam(mail) to .queryparam("mail", mail) solved it.

回答2:

Try to test with this :

   @RestController
    public class Controller {

    @Autowired
    private MessageRepository daoMsg;

    @RequestMapping(value = "/Mensajes", method = RequestMethod.GET, produces=MediaType.APPLICATION_JSON_VALUE)
    @ReponseBody
    public ResponseEntity<List<MessageObject>> enviados (@RequestParam("mail") String mail) {
        return new ResponseEntity<>(daoMsg.findByEmisorOrDestinatario(mail, mail), HttpStatus.OK);  

    }

来源：https://stackoverflow.com/questions/53659213/status-400-and-error-deserializing-list-of-objects-no-default-constructor-found

标签

json

Spring

rest

spring-boot

jsonb