Map an Object Property in a POJO given an ID from a JSON

Question

First of all, sorry, I cannot explain myself in any better way.

I am programming an example API, I have a POJO (with JPA) called Movie, so in my controller, I want to give it a JSON to insert a Movie.

Movie has a @ManyToOne(optional = false) property, relating another POJO called Genre ( idGenre , Name )

I want to give in a JSON not an object with every property but an id, so:

CONTROLLER

@RequestMapping(value = "/sendMovie", method = RequestMethod.POST)
public void setMovie(@RequestBody Movie movie) {
    mRepo.save(movie);
}

Movie

@Entity
public class Movie {

    @Id
    @Column(name = "ID_MOVIE", nullable = false)
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long idMovie;

    @Column(name = "NAME")
    private String name;

    @Column(name = "SYNOPSIS")
    private String synopsis;

    @Column(name = "POSTER")
    private String poster;

    @Column(name = "DIRECTOR")
    private String director;

    @JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "idGenre")
    @JsonIdentityReference(alwaysAsId = true)
    @ManyToOne(optional = false)
    @JoinColumn(name = "ID_GENRE", referencedColumnName = "ID_GENRE")
    private Genre genre;

JSON I want to use

{
  "name": "MATRIX",
  "idGenre": 3,
  "synopsis": "NEO DOING THINGS",
  "poster": "matrix.jpg",
  "director": "WACHOWSKIS"
 }

Is there possibility to achieve that?

Answer 1

You did put the JsonIdentity... annotations at the wrong place.

You need to put these annotations on your @Genre class:

@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "idGenre")
@JsonIdentityReference(alwaysAsId = true)
public class Genre {
    @Id
    @Column(...)
    private Long idGenre;

    //....
}

and remove these annotations from the property Genre genre in your Movie class. You also need to tell Jackson with @JsonProperty("idGenre") that you want this property serialized with name "idGenre" .

@ManyToOne(optional = false)
@JoinColumn(name = "ID_GENRE", referencedColumnName = "ID_GENRE")
@JsonProperty("idGenre")
private Genre genre;

Then the JSON output will be something like this:

{
  "name": "MATRIX",
  "synopsis": "NEO DOING THINGS",
  "poster": "matrix.jpg",
  "director": "WACHOWSKIS",
  "idGenre": 3
}