CODEWITHSUNDEEP
javajsonspringjackson
Eniss
Eniss

Reputation: 913

Multiple back-reference properties with name 'defaultReference'

I have multiple back-reference classes in a class. Since I use @JsonBackReference for them, I get an error. I assigned @JsonIdentityInfo annotation for those classes, but I still get the same error.

public class X implements Serializable {
  ....
  //bi-directional many-to-one association to Booking
  @ManyToOne(fetch = FetchType.EAGER)
  @JoinColumn(name = "xxA", nullable = false)
  @JsonBackReference
  private A a;

  //bi-directional many-to-one association to Client
  @ManyToOne(fetch = FetchType.EAGER)
  @JoinColumn(name = "xxB", nullable = false)
  @JsonBackReference
  private B b;
  ...getters setters
}

@JsonIdentityInfo(generator = ObjectIdGenerators.IntSequenceGenerator.class, property = "@id")
public class B implements Serializable {
  ........ 
  //bi-directional many-to-one association to BookedClient
  @OneToMany(mappedBy = "b", fetch = FetchType.EAGER, cascade = CascadeType.ALL)
  @JsonManagedReference
  private List < X > xxB;
  ........ getters setters
}


@JsonIdentityInfo(generator = ObjectIdGenerators.IntSequenceGenerator.class, property = "@id")
public class A implements Serializable {
  ........
  //bi-directional many-to-one association to BookedClient
  @OneToMany(mappedBy = "a", fetch = FetchType.EAGER, cascade = CascadeType.ALL)
  @JsonManagedReference
  private List < X > xxA;
  ........ getters setters
}

error:

com.fasterxml.jackson.databind.JsonMappingException: Multiple back-reference properties with name 'defaultReference'

How can I resolve this error? Can I not use multiple back-reference in a class?

Upvotes: 1

Views: 7540

Answers (3)

Marc Magon
Marc Magon

Reputation: 848

So this did actually take me a while...

You can annotate your referencse accordingly using @JsonIdentityReference(alwaysAsId = true) and then leave it off the master reference

    @JsonIdentityReference(alwaysAsId = true)
    private Set<PackInstructionGroup> groups = new TreeSet<>();

Upvotes: 0

Vivek Gangwar
Vivek Gangwar

Reputation: 1

I also faced this issue, but in the last I resolved it.

//This is parent class
@Entity
@Table(name = "checklist")
@JsonIgnoreProperties("inspection")
public class Checklist implements java.io.Serializable {

    @ManyToOne
    @JoinColumn(name = "product_id", referencedColumnName = "id")
    @JsonBackReference
    private Product product;

    @OneToMany(mappedBy = "checklists", cascade = CascadeType.ALL)
    @JsonManagedReference
    private Set<Inspection> inspection = new HashSet<Inspection>();
//Constructor
//Getter and Setter
}

//This is child class
@Entity
@Table(name = "inspections")
public class Inspection {

    @ManyToOne
    @JoinColumn(name = "chk_id", referencedColumnName = "id")
    private Checklist checklists;
//Constructor
//Getter and Setter
}

By mentioning @JsonIgnoreProperties("inspection") and @JsonManagedReference in Parent class

Resolved the issue raised by using two @JSONBackRefrence in same parent class.

Upvotes: 0

Sharon Ben Asher
Sharon Ben Asher

Reputation: 14383

According to Jackson's javadoc, both @JsonManagedReference and @JsonBackReference accept a name value that binds them together:

  @JsonBackReference("a")
  private A a;

  @JsonManagedReference("a")
  private List < X > xxA;

Upvotes: 1

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