Spring REST API, custom entity fields in the response

Question

I'm working in a REST API (Java, SpringBoot, QueryDsl...) and I would like to customize the fields that I have in the result. By default I'm obtaining all fields of the entity but the fields that I need depends on the request. This should be something dynamic.

As far as I know, using projections I can obtain something like this but I have to declare previously the projection and I would like to work with something dynamic not static. On the other hand I have seen than something like GraphQL allows this behaviour but I would have to refactor everything.

Has anyone had this problem before?

This is my code:

BaseRestCRUDController

public abstract class BaseRestCRUDController<T extends EntityBase, V extends BaseDTO> {

@GetMapping("/list")
  public ResponseEntity<List<V>> findAll(Predicate predicate, Pageable pageable) {
    log.info("FindAll");
    return new ResponseEntity(getCRUDService().findAll(predicate, pageable), HttpStatus.OK);
  }

}

ExampleController

@RestController
@RequestMapping("/api/example")
public class ExampleController
    extends BaseRestCRUDController<Example, ExampleDTO> {

  @Autowired 
  private ExampleService ExampleService;

  @Override
  public ResponseEntity<List<ExampleDTO>> findAll(
      @QuerydslPredicate(root = Example.class) Predicate predicate, Pageable pageable) {
     return super.findAll(predicate, pageable);
  }

  @Override
  protected CRUDService<Example, ExampleDTO> getCRUDService() {
    return ExampleService;
  }
  
}

Example (Entity)

public class Example {

  @Id
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  private Long id;

  @Column(name = "name", nullable = false)
  private String name;

  @Column(name = "creation_date")
  private Instant creationDate;

  @Column(name = "last_update")
  private Instant lastUpdate;

  @Column(name = "erasure_date")
  private Instant erasureDate;
}

• http://localhost:8080/api/example/list?name=test&page=0&size=5&sort=id,desc
• http://localhost:8080/api/example/list?name=foo&page=1&size=10&sort=id,desc
• http://localhost:8080/api/example/list?page=0&size=2&sort=id,asc

[
    {
        "id": 1,
        "name": "e1",
        "creationDate": "2021-11-15T23:00:00Z",
        "lastUpdate": null,
        "erasureDate": null
    },
    {
        "id": 2,
        "name": "e2",
        "creationDate": "2021-11-15T23:00:00Z",
        "lastUpdate": null,
        "erasureDate": null
    },
    {
        "id": 3,
        "name": "e3",
        "creationDate": "2021-11-15T23:00:00Z",
        "lastUpdate": null,
        "erasureDate": null
    }
]

How can I obtain something like this without use projections?

http://localhost:8080/api/example/list?fields=id,name&name=foo&page=1&size=10&sort=id,desc

[
    {
        "id": 1,
        "name": "e1"
    },
    {
        "id": 2,
        "name": "e2"
    },
    {
        "id": 3,
        "name": "e3"
    }
]

http://localhost:8080/api/example/list?fields=name&name=foo&page=1&size=10&sort=id,desc

[
    {
        "name": "e1",
    },
    {
        "name": "e2",
    },
    {
        "name": "e3",
    }
]

Answer 1

 @Ignore
 private Instant creationDate;

Try this. You can use @Ignore on getter,setter or fields.