I'm using Spring MVC and JSON to do some tasks, and i've got this exception

Question

I've been searching for three days, and my error still exist, I've tried a lot of solutions without any positive result !

I've ManyToMany relations, and here is my JPA mapping :

@Entity public class Facteur implements Serializable {

/**
 * 
 */
private static final long serialVersionUID = 1L;

@Id
@GeneratedValue(strategy=GenerationType.AUTO)
private Long idF;

.....

@ManyToMany
@LazyCollection(LazyCollectionOption.FALSE)
@JoinTable(name="Affectation",joinColumns=@JoinColumn(name="IdF"), inverseJoinColumns=@JoinColumn(name="idT"))
private List<Tournee> tournees;

.......

}

"Tournee" Class is like this

@Entity public class Tournee implements Serializable {

@Id
@GeneratedValue(strategy=GenerationType.AUTO)
private int idT;

....
@ManyToMany(mappedBy="tournees")
@LazyCollection(LazyCollectionOption.FALSE)
private List<Facteur> facteurs;

....

}

here is my controller :

@RequestMapping(value="/getFacteur/", method=RequestMethod.GET)
@ResponseBody
public Facteur getFacteurById(@RequestParam("id") Long idF) {
    Facteur f = facteurService.getById(idF);
    System.out.println(f.toString());
    return f;
}

and JQuery code is :

$(document).ready(function() {
        $(".updatelink").click(function() {
            var facteurId = $(this).data("facteur-id");
            $.ajax({
                type : "GET",
                url : "http://localhost:8080/distribution/facteur/getFacteur/",
                data : { id : facteurId },
                success : function(data) {
                            alert('SUCCESSS');
                            },
                error : function(){
                            alert("ERROR");
                }
            });
        });
    });

Any solutions ?

Best regards !

Answer 1

One of the two sides of the relationship should not be serialized in order to avoid the infinite loop that causes your stackoverflow error. You can use @JsonManagedReference and @JsonBackReference to avoid the error:

//class Facteur
@ManyToMany
@LazyCollection(LazyCollectionOption.FALSE)
@JoinTable(name="Affectation",joinColumns=@JoinColumn(name="IdF"), inverseJoinColumns=@JoinColumn(name="idT"))
@JsonManagedReference
private List<Tournee> tournees;

//class Tournee
@ManyToMany(mappedBy="tournees")
@LazyCollection(LazyCollectionOption.FALSE)
@JsonBackReference
private List<Facteur> facteurs;

Add the @JsonManagedReference in the forward part of the relationship which you want to serialize, and add @JsonBackReference in the back part of the relationship which will not be serialized. In fact, if you serialize a Tournee instance to JSON, you will not get the Facteur array instance. To avoid this drawback, just use the simple @JsonIgnore, but keep in mind, that therefore getters and setters will be ignored during serialization.

Answer 2

You are running into stackoverflow error since Facteur class has reference to tournees and Tournees in turn refers to Facteur - circular refernce while JSON serialization.
Just add @JsonIgnore annotation to private List<Tournee> tournees; declaration in Facteur class and you should be fine.