How to get Pojo name referenced Json object when we Jackson data-binding

Question

I am generating Rest Services using Jackson. I am able to get JSON response like

[{"userName":"scott","userId":7},{"userName":"toe","userId":101}]

but i am expecting response with Pojo name pointing to the response like below

{"UserDetails":[{"userName":"scott","userId":7},{"userName":"toe","userId":101}]}

Here is my implementation class

@Service("userServices")
public class UserServiceImpl implements UserServices{

private UserServices userServices;

public UserServices getUserServices() {
    return userServices;
}
public void setUserServices(UserServices userServices) {
    this.userServices = userServices;
}

@Override
public List<UserDetails> getUser(UserDetails userDetails) {


    ObjectMapper mapper = new ObjectMapper();

    List<UserDetails> user = new ArrayList<UserDetails>();
    List<UserDetails> list = new ArrayList<UserDetails>();

    UserDetails userDetails2 = new UserDetails();
    userDetails2.setUserName("scott");
    userDetails2.setUserId(007);

    UserDetails userDetails3 = new UserDetails();
    userDetails3.setUserName("toe");
    userDetails3.setUserId(101);

    user.add(userDetails2);
    user.add(userDetails3);

    try{
    String jsonString = mapper.writeValueAsString(user);
    UserDetails[] userDetails4 = mapper.readValue(jsonString, UserDetails[].class);
    list = Arrays.asList(userDetails4);
    System.out.println(userDetails4);
    }catch (Exception e) {
        System.out.println(e);
    }
    return list;
}
}

and here is my pojo

public class UserDetails implements Serializable{

private String userName;
private int userId;

public UserDetails(){

}

 //getters and setters...
}

** Note:** I don't want to use any annotations at the domain object side.

Answer 1

Just return

UserDetailsResponse:

public class UserDetailsResponse {

    private List<UserDetails> userDetails;
    // getter and setter

}

instead of list of UserDetails in the UserServiceImpl (and presumably then in the controller).

Answer 2

You return a List of UserDetails which translates to your response object being a JSON Array. In order to get your desired result you would need to create a Container class (UserDetailsContainer) which has the property userDetails of the List type and return an instance of that as your response.

Answer 3

You can use objectMapper.writeValueAsString(aCustomMap) for custom json view creation on the fly.

Example:

UserDetails userDetails2 = new UserDetails();
userDetails2.setUserName("scott");
userDetails2.setUserId(007);

UserDetails userDetails3 = new UserDetails();
userDetails3.setUserName("toe");
userDetails3.setUserId(101);

Map<String, List<UserDetails>> m = new HashMap<>();
m.put("UserDetails", Arrays.asList(userDetails2, userDetails3));

System.out.print(
    //This is what you need
    objectMapper.writeValueAsString(m)
);
//{"UserDetails":[{"userName":"scott","userId":7},{"userName":"toe","userId":101}]}