Spring JPARepository 查询多对多交集表

Question

我有如下 3 个实体类(示例取自 https://hellokoding.com/jpa-many-to-many-extra-columns-relationship-mapping-example-with-spring-boot-maven-and-mysql/)

读书课

@Entity
public class Book{
    private int id;
    private String name;
    private Set<BookPublisher> bookPublishers;

    public Book() {
    }

    public Book(String name) {
        this.name = name;
        bookPublishers = new HashSet<>();
    }

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @OneToMany(mappedBy = "book", cascade = CascadeType.ALL, orphanRemoval = true)
    public Set<BookPublisher>   getBookPublishers() {
        return bookPublishers;
    }

    public void setBookPublishers(Set<BookPublisher> bookPublishers) {
        this.bookPublishers = bookPublishers;
    }
}

发布者类

@Entity
public class Publisher {
    private int id;
    private String name;
    private Set<BookPublisher> bookPublishers;

    public Publisher(){

    }

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

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @OneToMany(mappedBy = "publisher")
    public Set<BookPublisher> getBookPublishers() {
        return bookPublishers;
    }

    public void setBookPublishers(Set<BookPublisher> bookPublishers) {
        this.bookPublishers = bookPublishers;
    }
}

交集表

@Entity
@Table(name = "book_publisher")
public class BookPublisher implements Serializable{
    private Book book;
    private Publisher publisher;
    private Date publishedDate;

    @Id
    @ManyToOne
    @JoinColumn(name = "book_id")
    public Book getBook() {
        return book;
    }

    public void setBook(Book book) {
        this.book = book;
    }

    @Id
    @ManyToOne
    @JoinColumn(name = "publisher_id")
    public Publisher getPublisher() {
        return publisher;
    }

    public void setPublisher(Publisher publisher) {
        this.publisher = publisher;
    }

    @Column(name = "published_date")
    public Date getPublishedDate() {
        return publishedDate;
    }

    public void setPublishedDate(Date publishedDate) {
        this.publishedDate = publishedDate;
    }
}

我想查询两件事，

1. 获取属于特定出版商的图书列表，例如获取与出版商 100 关联的所有图书
2. 获取与特定出版商无关的图书列表，例如获取所有与出版商无关的图书 100

如果可能的话，我想使用简单的 JPARepository 查询来实现这一点，例如 findByXYZIn(...) 等。

请告诉我是否可以使用 JPA 存储库查询来查询多对多关系，如果可以，我是否可以直接执行此操作还是需要对实体类进行任何更改

Answer 1

在 BookRepository

获取出版商的书籍

findBooksByBookPublishersPublisherId(长型 publisherId)

获取非出版商出版的图书

findBooksByBookPublishersPublisherIdNot(Long publisherId)

恕我直言 Publication 比 BookPublisher 更合适，在你的情况下 Publisher 本身可以是 BookPublisher (a published 即出版书籍)