[FIXED] @JsonIgnore works correctly with normal relations but when i apply a many to many to the same entity it doesn't work

Issue

@JsonIgnore doesn't work when a relationship is applient to the same entity but when used in the relationship with a different entity it works fine i want to use it to stop the recursive problem with json is there a way to fix this or using something different than @JsonIgnore and if someone know the answer please share with me the cause of the problem so i can avoid this in the future. Thank you in advance.

    package com.socialapp.model;

import com.fasterxml.jackson.annotation.JsonIgnore;

import javax.persistence.*;
import java.util.HashSet;
import java.util.Set;

@Entity
@Table(name = "users")
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;

    @Column(unique = true,name = "username")
    private String Username;

    @Column(unique = true,name = "mail")
    private String mail;

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

    @JsonIgnore //this is a one to many relationship with entity post works fine
    @OneToMany(mappedBy = "poster")
    private Set<Post>  posts= new HashSet<>();

    @JsonIgnore //this is a many to many relationship with entity post works fine
    @ManyToMany(mappedBy = "likers")
    private Set<Post> postsLiked = new HashSet<>();


    @ManyToMany
    @JoinTable(
            name = "follow",
            joinColumns = @JoinColumn(name = "followers"),
            inverseJoinColumns = @JoinColumn(name = "following")
    )
    private Set<User> Followers = new HashSet<>();

    @JsonIgnore  //this is a many to many relationship with the same entity @jsonignore doesn't work
    @ManyToMany(mappedBy = "Followers")
    private Set<User> Following = new HashSet<>();


    public User(String username, String mail, String password) {
        Username = username;
        this.mail = mail;
        this.password = password;
    }

    public User() {
    }

    public long getId() {
        return id;
    }

    public void setId(long id) {
        this.id = id;
    }

    public String getUsername() {
        return Username;
    }

    public void setUsername(String username) {
        Username = username;
    }

    public String getMail() {
        return mail;
    }

    public void setMail(String mail) {
        this.mail = mail;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }
    public Set<Post> getPosts() {
        return posts;
    }

    public void setPosts(Set<Post> posts) {
        this.posts = posts;
    }

    public Set<Post> getPostsLiked() {
        return postsLiked;
    }

    public void setPostsLiked(Set<Post> postsLiked) {
        this.postsLiked = postsLiked;
    }

    public Set<User> getFollowers() {
        return Followers;
    }

    public void setFollowers(Set<User> followers) {
        Followers = followers;
    }

    public Set<User> getFollowing() {
        return Following;
    }

    public void setFollowing(Set<User> following) {
        Following = following;
    }
    public void addFollower(User following){
        this.Followers.add(following);
    }
}

"id": 1, "mail": "[email protected]", "password": "78824381", "followers": [ { "id": 2, "mail": "[email protected]", "password": "123456", "followers": [], "following": [ { "id": 1, "mail": "[email protected]", "password": "78824381", "followers": [ { "id": 2, "mail": "[email protected]", "password": "123456", "followers": [], "following": [ { "id": 1, "mail": "[email protected]", "password": "78824381", "followers": [ { "id": 2, "mail": "[email protected]", "password": "123456", "followers": [], "following": [ { "id": 1, "mail": "[email protected]", "password": "78824381", "followers": [ { "id": 2, "mail": "[email protected]", "password": "123456", "followers": [], "following": [ { "id": 1, "mail": "[email protected]", "password": "78824381", "followers": [ { "id": 2,

Solution

I think that your answer is here https://www.baeldung.com/jackson-bidirectional-relationships-and-infinite-recursion

Pay attention to paragraph 3and the annotations @JsonManagedReference and @JsonBackReference.

By using JsonManagedReference you can avoid the circular dependency issue.

Answered By - XII
Answer Checked By - David Goodson (JavaFixing Volunteer)