[JAVA] StackOverflowError to String causes a circular reference

error contents

java.lang.StackOverflowError
	at java.lang.AbstractStringBuilder.append(AbstractStringBuilder.java:675)
	at java.lang.StringBuilder.append(StringBuilder.java:208)
	at java.time.LocalDate.toString(LocalDate.java:2032)
	at java.lang.String.valueOf(String.java:2994)
	at java.lang.StringBuilder.append(StringBuilder.java:131)
	at demo.model.User.toString(User.java:19)
...

Before correction

The relationship between User and UserDetail is a OneToOne two-way relationship.

User

@Entity
@Data
public class User {

	@OneToOne(mappedBy = "user", cascade = CascadeType.ALL)
	private UserDetail userDetail;

UserDetail

@Entity
@Data
public class UserDetail implements Serializable {

	@OneToOne
	@JoinColumn
	@MapsId
	private User user;

Cause of circulation

I forgot that adding @Data in Lombok will also add `` `@ Getter / @ Setter``` and @ToString. .. ..

Where is the circulation happening? .. When User.toString is executed, DetailUser.toString is executed, and User.toString is further called in it to start circulation.

How to solve

Avoid calling DetailUser when User.toString is executed

User

@Entity
@Data
public class User {

	@OneToOne(mappedBy = "user", cascade = CascadeType.ALL)
	@ToString.Exclude //★★★ Define fields to exclude from toString
	private UserDetail userDetail;