JSON 没有显示它在 Postman 中应该如何显示

Question

当我尝试调用 REST 端点时，我的 Postman 有一些奇怪的行为。有一个永无止境的循环。我在 stackoverflow 上找到了一个解决方案，@JsonIgnore 注释将删除这个奇怪的循环（我在下面的 Book 实体中有它）但是当我尝试在 Postman 中列出所有书籍时，我看不到这些书籍的作者。是否有更好的解决方案来显示作者的书籍（删除 @JsonIgnore 注释）但也删除那个奇怪的循环？

Book.java

@Entity

public class Book {

    @Id

    @GeneratedValue(strategy = GenerationType.IDENTITY)

    private Long id;

    private String title;

    private String isbn;

    @ManyToMany

    @JsonIgnore // removed wierd loop with data

    @JoinTable(name = "author_book", joinColumns = @JoinColumn(name = "book_id"),

            inverseJoinColumns = @JoinColumn(name = "author_id"))

    private Set<Author> authors = new HashSet<>();

    public Book() {

    }

Author.java

@Entity

public class Author {

    @Id

    @GeneratedValue(strategy = GenerationType.AUTO)

    private Long id;

    private String forename;

    private String surname;

    @ManyToMany(mappedBy = "authors")

    private Set<Book> books = new HashSet<>();

    public Author() {

    }

BookController.java

@RestController

public class BookController {

    private BookService bookService;

    @Autowired

    public BookController(BookService bookService) {

        this.bookService = bookService;

    }

    // expose /books and get list of all books - GET

    @GetMapping("/api/books")

    public List<Book> getAllBooks() {

        return bookService.getAllBooks();

    }

AuthorController 与 BookController 相同。

这是 Book JSON 在 Postman 中的样子（这些书没有作者）：

Postman 中的 Authors 没问题：

这是我从 Book 实体中删除 @JsonIgnore 时的循环：

Answer 1

使用@JsonIgnoreProperties注解为了忽略一个字段上的子字段，那么这个注解会忽略二级字段。Book&nbsp;&nbsp; &nbsp; - >&nbsp; authors&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; -> books&nbsp; // this field is ignoredAuthor&nbsp;&nbsp; &nbsp; - >&nbsp; books&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; -> authors // this field is ignored@ManyToMany@JsonIgnoreProperties("books")@JoinTable(name = "author_book", joinColumns = @JoinColumn(name = "book_id"),&nbsp; &nbsp; &nbsp; &nbsp; inverseJoinColumns = @JoinColumn(name = "author_id"))private Set<Author> authors = new HashSet<>();@ManyToMany(mappedBy = "authors")@JsonIgnoreProperties("authors")private Set<Book> books = new HashSet<>();