Best approach to create different JSON response from same Entity - spring-boot

Question

I have an entity class User with 20 fields, some of them being confidential fields. I have a controller class, which has a method getUser to fetch all the user from DB and send the JSON respone. Below is the sample code for the same:
#GetMapping("/getUsers")
public UserDT getUsers( Model theModel) {
List<User> userList;
userList = userService.findAll();
return userList;
}
When I run the above code, it returns all the fields from User table/User Entity Class. Instead of sending all the fields, I would like to send selected fields say Field1 to Field5 only.
Ultimate goal is to have multiple views for the same Entity Class. For URL1 I would like to show only field1 to field5 of User table, But for URL2 I would like to show Field9 , Filed15, Field20.
Do I need to create multiple Entity Class for each URL? Please guide me with the best practice to be followed in such scenario.

Answer 1

Assuming you are using Spring Data JPA, use projections.
So create different projections for your different URLs write a method that returns the projection (or a dynamic one as in the documentation).
public interface NamesOnlyProjection {
String getFirstName();
String getLastName();
}
public interface UserinfoProjection {
String getUsername();
String getPassword();
String getDepartment();
}
Then in your repository do something like this
public interface PersonRepository extends JpaRepository<Person, Long> {
<T> List<T> findAll(Class<T> type);
}
Then you can do something like this in your controller/service
#RestController
public class PersonController {
private final PersonRepository persons;
#GetMapping("/people/names")
public List<NamesOnlyProjection> allNames() {
return persons.findAll(NamesOnlyProjection.class);
}
#GetMapping("/people/users")
public List<UserinfoProjection> allNames() {
return persons.findAll(UserinfoProjection.class);
}
}