how to develop JPA bi-directional entities in spring toot - jpa

Question

I am new to spring boot and jpa/hibernate, please bear my inaccurate usage of the terminologies.
I have two entities: book and address. A book is published in a certain city which is stored in "address", a "address" can publish multiple books.
The DB schema for book is: id, name, author, price, addressid
schema for address: addressid, addressCountry, addressCity
The entity for book:
#Entity
#Table(name = "test_book")
public class Book implements Serializable {
private static final long serialVersionUID = 8025948150436422040L;
#Id
long id;
#Column(name = "name")
String name;
#Column(name = "author")
String author;
#Column(name = "price")
long price;
#ManyToOne
#JoinColumn(name = "addressid")
private Address address;
...//getter and setter
The entity for address
#Entity
#Table(name = "test_address")
public class Address implements Serializable{
private static final long serialVersionUID = -3541059157210384355L;
#Id
#Column(name= "addressid")
private long addressId;
#Column(name="addresscountry")
private String addressCountry;
#Column(name="addresscity")
private String addressCity;
#OneToMany(mappedBy = "address")
private Collection<Book> books;
...//getter setter
But when I call the Restful service, I get infinite loop...
[{"id":11,"name":"Java Book","author":"Jame Gosling","price":100,"address":{"addressId":1,"addressCountry":"China","addressCity":"Shanghai","books":[{"id":11,"name":"Java Book","author":"Jame Gosling","price":100,"address":...
I did some search. And my request is:
when I search a book, I can get the information: id, name, author, price, address..
And also I can query a address to get all the books the city published.
When I add Json Annotation #JsonManagedReference in address and #JsonBackReference in book entity, I can query book but cannot get address information.
Could you please help how to solve the problems? Thank you very much.

Answer 1

You can ignore the #JsonIgnore on getter for books. This will exclude the Collection<Book> books property from serialization the Address.
Link : JacksonAnnotations - Faster XML Wiki
Example:
#JsonIgnore
public Collection<Book> getBooks() {
...
}

Answer 2

#JsonIgnore
The Jackson annotation #JsonIgnore is used to tell Jackson to ignore a
certain property (field) of a Java object. The property is ignored
both when reading JSON into Java objects, and when writing Java
objects into JSON.
In your case this is happening as there is bidirectional relationship and so it will go into loop. To stop this you need to provide JsonIgnore
And so your code will be like :
-> The entity for address
#Entity
#Table(name = "test_address")
public class Address implements Serializable{
private static final long serialVersionUID = -3541059157210384355L;
#Id
#Column(name= "addressid")
private long addressId;
#Column(name="addresscountry")
private String addressCountry;
#Column(name="addresscity")
private String addressCity;
#OneToMany(mappedBy = "address")
#JsonIgnore
private Collection<Book> books;