REST API Infinite loop - spring-boot

Question

My API shows me infinite loop for adress field
When I insert #JsonIgnore, #JsonManagedReference or #JsonBackReference
I can clearly see one result as it should be, but than i don't have nested address fields.
What should I do to have also that address fields but one result?
These are my main entities:
1.Property
package com.realestate.petfriendly.entity;
import com.fasterxml.jackson.annotation.JsonBackReference;
import com.fasterxml.jackson.annotation.JsonIgnore;
import java.io.Serializable;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.OneToOne;
import javax.persistence.Table;
import lombok.Data;
#Entity
#Data
#Table(name = "property")
public class Property {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id_property")
private int id_property;
#Column(name = "title")
private String title;
#Column(name = "type")
private String type;
#Column(name = "room")
private String room;
#Column(name = "price")
private double price;
#OneToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
#JoinColumn(name = "address_id_address")
// #JsonBackReference
private Address address;
#ManyToOne(fetch = FetchType.LAZY, optional = false)
#JoinColumn(name = "user_id_user")
// #JsonBackReference
private User user;
}
User
package com.realestate.petfriendly.entity;
import com.fasterxml.jackson.annotation.JsonManagedReference;
import java.util.ArrayList;
import java.util.List;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToMany;
import javax.persistence.OneToOne;
import javax.persistence.Table;
import lombok.Getter;
import lombok.Setter;
#Entity
#Getter
#Setter
#Table(name = "user")
class User {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id_user")
private int id_user;
#Column(name = "username")
private String username;
#Column(name = "name")
private String name;
#Column(name = "lastname")
private String lastname;
#Column(name = "phone")
private String phone;
#Column(name = "notes")
private String notes;
#OneToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
#JoinColumn(name = "user_address_id_user_address")
// #JsonManagedReference
private UserAddress userAddress;
#OneToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL, mappedBy = "user")
// #JsonManagedReference
private List<Property> property = new ArrayList<>();
}
Address
package com.realestate.petfriendly.entity;
import com.fasterxml.jackson.annotation.JsonManagedReference;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToOne;
import javax.persistence.Table;
import lombok.Getter;
import lombok.Setter;
#Entity
#Getter
#Setter
#Table(name="address")
class Address{
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id_address")
private int id_address;
#Column(name = "city")
private String city;
#Column(name = "municipality")
private String municipality;
#Column(name = "place")
private String place;
#Column(name = "street")
private String street;
#Column(name = "house_number")
private double house_number;
#OneToOne(mappedBy = "address")
// #JsonManagedReference
private Property property;
}

Answer 1

You actually have the solution to your problem in your code, but the key annotations are commented-out and in the wrong places (according to your requirements). One of the ways to tackle this is by using #JsonManagedReference and #JsonBackReference as follows:
#Entity
#Data
#Table(name = "property")
public class Property {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id_property")
private int id_property;
#Column(name = "title")
private String title;
#Column(name = "type")
private String type;
#Column(name = "room")
private String room;
#Column(name = "price")
private double price;
#OneToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
#JoinColumn(name = "address_id_address")
#JsonManagedReference
private Address address;
#ManyToOne(fetch = FetchType.LAZY, optional = false)
#JoinColumn(name = "user_id_user")
#JsonBackReference
private User user;
}
#Entity
#Getter
#Setter
#Table(name = "user")
class User {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id_user")
private int id_user;
#Column(name = "username")
private String username;
#Column(name = "name")
private String name;
#Column(name = "lastname")
private String lastname;
#Column(name = "phone")
private String phone;
#Column(name = "notes")
private String notes;
#OneToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
#JoinColumn(name = "user_address_id_user_address")
private UserAddress userAddress;
#OneToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL, mappedBy = "user")
#JsonManagedReference
private List<Property> property = new ArrayList<>();
}
#Entity
#Getter
#Setter
#Table(name="address")
class Address{
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id_address")
private int id_address;
#Column(name = "city")
private String city;
#Column(name = "municipality")
private String municipality;
#Column(name = "place")
private String place;
#Column(name = "street")
private String street;
#Column(name = "house_number")
private double house_number;
#OneToOne(mappedBy = "address")
#JsonBackReference
private Property property;
}
Keep in mind the following:
#JsonManagedReference is the forward part of the relationship: the one that gets serialized normally.
#JsonBackReference is the back part of the relationship: it will be omitted from serialization.
If you want to have a reference to the back part of the relationship, you can use #JsonIdentityInfo as follows:
#Entity
#Data
#Table(name = "property")
#JsonIdentityInfo(
generator = ObjectIdGenerators.PropertyGenerator.class,
property = "id_property")
public class Property {
(...)
}
#Entity
#Getter
#Setter
#Table(name = "user")
#JsonIdentityInfo(
generator = ObjectIdGenerators.PropertyGenerator.class,
property = "id_user")
class User {
(...)
}
#Entity
#Getter
#Setter
#Table(name="address")
#JsonIdentityInfo(
generator = ObjectIdGenerators.PropertyGenerator.class,
property = "id_address")
class Address{
(...)
}
You can read more about these and other techniques in the following online resource: https://www.baeldung.com/jackson-bidirectional-relationships-and-infinite-recursion.

Answer 2

You have circular dependency between Property and Address class. In order to block infinite JSON serialization loop you can add #JsonIgnore annotation on one side of related properties