Infinite recursion with Jackson on intermediate table

I am using Spring Boot and Jackson and Hibernate to create an API. Hibernate connects to a MySQL database.
I understand the good practices but I'm stuck on a particular point.
I have an n:m relationship that contains an extra field.

Ex: Author(id, ...) -> Written(idAuthor, idBook, date) <- Book(id, ...)

I understand how to map a traditional n:m relationship, but this technique does not apply to me this time.

For this, I found a source on the internet that showed the solution: create an intermediate class in my code that contains an Author type object and a Book type object + my additional fields.

@Entity
@Table(name = "Author")
public class Author implements Serializable {
/...
 
    @Id
    @GeneratedValue
    private int id;

    @OneToMany(mappedBy = "author", cascade = CascadeType.ALL)
    private Set<Written> written= new HashSet<>();
/...
}

@Entity
@Table(name = "Book")
public class Book implements Serializable{
/...

	@Id
    @GeneratedValue
    private int id;

    @OneToMany(mappedBy = "book", cascade = CascadeType.ALL)
    private Set<Written> written= new HashSet<>();
/...
}


public class Written implements Serializable {

    @Id
    @ManyToOne
    @JoinColumn(name = "idAuthor")
    private Author author;

    @Id
    @ManyToOne
    @JoinColumn(name = "idBook")
    private Book book;

    //Extra fields ....

}

That's a bidirectional link.
With this code, I get an infinite recursivity error:

Resolved [org.springframework.http.converter.HttpMessageNotWritableException: Could not write JSON: Infinite recursion (StackOverflowError); nested exception is com.fasterxml.jackson.databind.JsonMappingException: Infinite recursion (StackOverflowError) (through reference chain: java.util.ArrayList[0]->com.exampleAPI.api.model.Book["written"])]

I tried to use @JsonIgnore, @JsonManagedReference and @JsonBackReference on the Written class, also tried to use transient keyword, but nothing worked.

I can't find any source on the internet that could help me, and neither can the documentation for this particular case.

Can someone help me?

When unhandled bidirectional relationship occurs, Jackson faces infinite recursion.

> I tried to use @JsonIgnore, @JsonManagedReference and @JsonBackReference on the Written class

You need to use @JsonManagedReference and @JsonBackReference annotations separately to prevent these cycles between Book and Written. A side note, transient has nothing to do with the persistence but the serialization. JPA works with the @Transient annotation.

public class Book implements Serializable {

    @OneToMany(mappedBy = "book", cascade = CascadeType.ALL)
    @JsonBackReference
    private Set<Written> written= new HashSet<>();

    ...
}

public class Written implements Serializable {

    @Id
    @ManyToOne
    @JoinColumn(name = "idBook")
    @JsonManagedReference
    private Book book;

    ...
}

Important: Don't send database entities through REST (probably what you are up to do). Better create a DAO object without bidirectional relationship and map entities into DAOs. There are several libraries able to do that: I highly recommend MapStruct, however ModelMapper is also an option. If there is a lower number of such entities, using constructors/getters/setters would be enough.