Generics with Spring RESTTemplate

Question

I have a class like that:

public class Wrapper {

 private String message;
 private T data;

 public String getMessage() {
    return message;
 }

          


        

Answer 1

The only thing I think you could do is creating a new class that extends Wrapper and uses model as a generic.

class WrapperWithModel extends Wrapper<Model>{};

WrapperWithModel response = restTemplate.getForObject(URL, WrapperWithModel.class);

It's not the best solution, but at least you won't have to unmarshall manually the response.

Answer 2

Do not use generics with RestTemplate. Wrap request and response object with wrapper object that will hide the generics.

Answer 3

        ResponseEntity<Result>
                response = restTemplate.postForEntity("/user", user, Result.class);

        ObjectMapper objectMapper=new ObjectMapper();
        String content = objectMapper.writeValueAsString(response.getBody().getData());
        User user1 = objectMapper.readValue(content, User.class);

Answer 4

ParameterizedTypeReference has been introduced in 3.2 M2 to workaround this issue.

Wrapper<Model> response = restClient.exchange(loginUrl, 
                          HttpMethod.GET, 
                          null, 
                          new ParameterizedTypeReference<Wrapper<Model>>() {}).getBody();

However, the postForObject/getForObject variant was not introduced.