Spring JPA ManytoMany 对任何对象的循环引用

问题描述

我在代码中有以下实体和关系，

Book.java

@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
@ToString
@Entity
@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class,property = "id")
public class Book {
  @Id
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  private Integer id;

  private String name;

  @OnetoMany(mappedBy = "book",fetch = FetchType.LAZY)
  private Set<BookPublisher> bookPublishers = new HashSet<>();

  public Book(String name) {
    this.name = name;
  }
}

BookPublisher.java

@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
@ToString
@Entity
@Table(name = "book_publisher")
public class BookPublisher {

  @EmbeddedId
  private BookPublisherId id;

  @ManyToOne(fetch = FetchType.LAZY,optional = false)
  @MapsId("bookId")
  @JoinColumn(name = "book_id")
  private Book book;

  @ManyToOne(fetch = FetchType.LAZY,optional = false)
  @MapsId("publisherId")
  @JoinColumn(name = "publisher_id")
  private Publisher publisher;

  @Column(name = "published_date")
  private Date publishedDate;

  public BookPublisher(Book book,Publisher publisher,Date publishedDate) {
    this.id = new BookPublisherId(book.getId(),publisher.getId());
    this.book = book;
    this.publisher = publisher;
    this.publishedDate = publishedDate;
  }
}

发布者.java

@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
@ToString
@Entity
@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class,property = "id")
public class Publisher {
  @Id
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  private Integer id;

  private String name;

  @OnetoMany(mappedBy = "publisher",fetch = FetchType.LAZY)
  private Set<BookPublisher> bookPublishers = new HashSet<>();

  public Publisher(String name) {
    this.name = name;
  }
}

BookPublisherId.java

@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
@ToString
@Embeddable
public class BookPublisherId implements Serializable {
  @Column(name = "book_id")
  private Integer bookId;

  @Column(name = "publisher_id")
  private Integer publisherId;
}

问题 1： 按 Book、Publisher、BookPublisher 的顺序插入工作正常。但是 findAll() 不会返回任何存储库的结果，并且它会导致始终循环查询以下语句， 使用：

select bookpublis0_.book_id as book_id1_1_0_,bookpublis0_.publisher_id as publishe2_1_0_,bookpublis0_.book_id as book_id1_1_1_,bookpublis0_.publisher_id as publishe2_1_1_,bookpublis0_.published_date as publishe3_1_1_ from book_publisher bookpublis0_ where bookpublis0_.book_id=?

怎么了？

问题 2： 如何查询出版商 ID = 的图书对象？具有以下对象结构？ findBookByPublisherID("1")

{
  "book_id": "1","publishers": [
   {
      "publisher_id": "1",...
   },{
      "publisher_id": "2",...
   }
]
}

解决方法

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