JPA ManyToMany 失败，“列数必须与引用的主键相同”

Question

我有三个表customer、product 和sales。 sales 是存储客户产品的连接表，如下图所示： customer, product and Sales tables

我的实体定义如下：

客户.java

@Entity
@Table(name="customer")
public class Customer {
    @Id
    @Column(name="c_id")
    private String customerId;
    
    @Column(name="customer_name")
    private String customerName;
    
    @ManyToMany
    @JoinTable(
            name = "sale",
            joinColumns = @JoinColumn(name = "c_id"),
            inverseJoinColumns = @JoinColumn(name = "p_id"))
    private Set<Product> customerProducts = new HashSet<>();
}

Product.java

@Entity
@Table(name="product")
public class Product {
    @Id
    @Column(name="p_id")
    private String productId;
    
    @Column(name="product_name")
    private String productName;
    
    @Column(name="price")
    private Double price;

    // ... Setters & Getters
}

Sales.java

@Entity
@Table(name="sales")
public class Sales {
    @EmbeddedId
    private SalesPK salesId;
    
    @Column(name="qty")
    private Long qty;

    // ... Setters & Getters
}

SalesPK.java

@Embeddable
public class SalesPK implements Serializable {
    @Column(name = "c_id")
    private String customerId;
    @Column(name = "p_id")
    private String productId;
    public SalesPK() {}

    public SalesPK(String customerId, String productId) {
        this.customerId = customerId;
        this.productId = productId;
    }
}

CustomerRepository.java

@Repository
public interface CustomerRepository extends CrudRepository<Customer, String> {
    @Query("select customer from Customer customer " +
            "left join fetch customer.customerProducts " +
            "where customer.customerName = :customerName")
    public Customer getCustomerPurchasedProducts(String customerName);
}

我的 Spring Boot 应用程序无法启动并出现以下异常：

org.hibernate.MappingException: 外键 (FK7wwx8x75009xqb1y0tawm8rty:SALES [p_id])) 必须有相同数量的 列作为引用的主键 (SALES [c_id,p_id])

我在这里缺少什么？我已按照https://www.baeldung.com/jpa-many-to-many

中所述的说明进行操作

更新：

上述解决方案没有问题，我在@ManyToMany 声明中拼错了“sales”表，从“sale”更改为“sales”解决了这个问题。奇怪的行为，为什么它没有对丢失的表进行编译，而是抱怨实际的复合主键定义。

以下代码修复了问题：

    @ManyToMany
    @JoinTable(
            name = "sales",
            joinColumns = @JoinColumn(name = "c_id"),
            inverseJoinColumns = @JoinColumn(name = "p_id"))
    private Set<Product> customerProducts = new HashSet<>();
}

Answer 1

我会对这些类进行一些不同的映射：

@Entity
@Table(name="customer")
public class Customer {
    @Id
    @Column(name="c_id")
    private String customerId;
    
    @Column(name="customer_name")
    private String customerName;
    
    @OneToMany(mappedBy = "customer")
    private Set<Sale> customerSales = new HashSet<>();
}


@Entity
@Table(name="product")
public class Product {
    @Id
    @Column(name="p_id")
    private String productId;
    
    @Column(name="product_name")
    private String productName;
    
    @Column(name="price")
    private Double price;
}


@Entity
@Table(name="sales")
public class Sales {
    @EmbeddedId
    private SalesPK salesId;
    
    @MapsId("customerId") // maps customerId attribute of embedded id
    @ManyToOne
    Customer customer;
    
    @MapsId("productId") // maps productId attribute of embedded id
    @ManyToOne
    Product product;
    
    @Column(name="qty")
    private Long qty;

    // ... Setters & Getters
}


@Embeddable
public class SalesPK implements Serializable {
    @Column(name = "c_id")
    private String customerId;

    @Column(name = "p_id")
    private String productId;

    public SalesPK() {}

    public SalesPK(String customerId, String productId) {
        this.customerId = customerId;
        this.productId = productId;
    }
}