用于双向映射的实体错误映射中的 Hibernate JPA 重复列

Question

我有两个实体，sale 和 sale_details。一次销售会有很多销售细节，但每个销售细节只属于一个销售，我当前的代码在映射实体错误时给了我一个重复列。

销售：

@Entity
@Table(name="Sales")
public class Sale implements Serializable{

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "sale_id", nullable = false)
    private int sale_id;

    @Column(name = "promotionid_fk")
    private int promotionid_fk;

    @Column(name = "grand_total", nullable = false)
    private double grand_total;

    @Column(name = "salespersonid_fk", nullable = false)
    private int salespersonid_fk;

    @Column(name = "customerid_fk", nullable = false)
    private int customerid_fk;

    @Column(name = "storeid_fk", nullable = false)
    private int storeid_fk;

    @Column(name = "expected_date", nullable = false)
    private Date expected_date;

    @Column(name = "pickup_date")
    private Date pickup_date;

    @Column(name = "initial_deposit_date", nullable = false)
    private LocalDateTime initial_deposit_date;

    @Column(name = "initial_deposit_type", nullable = false)
    private String initial_deposit_type;

    @Column(name = "initial_deposit_amount", nullable = false)
    private double initial_deposit_amount;

    @Column(name = "final_payment_date")
    private LocalDateTime final_payment_date;

    @Column(name = "final_payment_type")
    private String final_payment_type;

    @Column(name = "final_payment_amount")
    private double final_payment_amount;

    //maps one sale to many sale details relationship
    @OneToMany(mappedBy = "sale", fetch = FetchType.LAZY)
    private List<SaleDetails> sale_detail_list; //stores list of sale_detail entries where FK saleid_fk field is the ID of this sale


    //default constructor, never used
    public Sale() {
    }

    //creates new sale
    public Sale(int promotionid_fk, double grand_total, int salespersonid_fk, int customerid_fk, int storeid_fk, Date expected_date, LocalDateTime initial_payment_date, String initial_payment_type, double initial_payment_amount) {
        this.promotionid_fk = promotionid_fk;
        this.grand_total = grand_total;
        this.salespersonid_fk = salespersonid_fk;
        this.customerid_fk = customerid_fk;
        this.storeid_fk = storeid_fk;
        this.expected_date = expected_date;
        this.initial_deposit_date = initial_payment_date;
        this.initial_deposit_type = initial_payment_type;
        this.initial_deposit_amount = initial_payment_amount;
    }

销售详情：

@Entity
@Table(name = "sale_Details")
public class SaleDetails implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "sale_detail_id")
    private int saleDetailId;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "saleid_fk")
    private Sale sale;

    @Column(name = "saleid_fk")
    private int saleid_fk;

    @Column(name = "productid_fk")
    private int productid_fk;

    @Column(name = "quantity_sold")
    private int quantity_sold;

    public SaleDetails(){
    }

    public SaleDetails(int saleid_fk, int productid_fk, int quantity_sold){
        this.saleid_fk = saleid_fk;
        this.productid_fk = productid_fk;
        this.quantity_sold = quantity_sold;
    }

表结构：

我试图建立双向关系，我在这里做错了什么？据我了解，关系的拥有方是 sale_details 实体上的多对一，而销售实体中的 mappedby 只是引用反面已经存在映射？

完整的错误堆栈跟踪：

Unable to build Hibernate SessionFactory
org.hibernate.MappingException: Repeated column in mapping for entity: com.owl.server.entities.Sale_Details column: saleid_fk (should be mapped with insert="false" update="false")

Answer 1

我建议你关注java naming conventions。根据这个角色：

类：类名应该是名词，大小写混合，每个内部单词的首字母大写。

变量：除变量外，所有实例、类和类常量都是大小写混合，首字母小写。内部单词以大写字母开头。

因此，我建议您通过以下方式更正您的映射：

@Entity
@Table(name="Sales")
public class Sale implements Serializable{

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "sale_id", nullable = false)
    private int saleId;

    @Column(name = "promotionid_fk")
    private int promotionId;

    // ...

    //maps one sale to many sale details relationship
    @OneToMany(mappedBy = "sale", fetch = FetchType.LAZY, cascade = CascadeType.ALL)
    private List<SaleDetails> saleDetails;


    // default constructor, should be present
    // It is used by hibernate for entity instantiation
    public Sale() {
       saleDetails = new ArrayList<>();
    }

    // getters, setters

    // The addSaleDetail() and removeSaleDetail() are utility methods that
    // synchronize both ends whenever a child element is added or removed.
    public void addSaleDetail(SaleDetails saleDetail)
    {
        saleDetails.add(saleDetail);
        saleDetail.setSale(this);
    }

    public void removeSaleDetail(SaleDetails saleDetail)
    {
        saleDetails.remove(saleDetail);
        saleDetail.setSale(null);
    }
}

@Entity
@Table(name = "Sale_Details")
public class SaleDetails implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "sale_detail_id")
    private int saleDetailId;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "saleid_fk")
    private Sale sale;

    // This should be removed
    // @Column(name = "saleid_fk")
    // private int saleid_fk;

    @Column(name = "productid_fk")
    private int productId;

    // ...

    public SaleDetails(){
    }

    // getters, setters
}

1. mappedBy中的值引用了关联另一方的字段名。

2. 如果外键引用目标实体的主键字段，则可以省略使用referencedColumnName。

还有一个创建和保存新销售的示例：

Sale sale = new Sale();
sale.setPromotionId(1);

// ...
SaleDetails saleDetail1 = new SaleDetails();
saleDetail1.setProductId(2);
// set other fields except sale
sale.addSaleDetail(saleDetail1);

SaleDetails saleDetail2 = new SaleDetails();
saleDetail2.setProductId(3);
// set other fields except sale
sale.addSaleDetail(saleDetail2);

entityManager.persist(sale);