java - 数据库的自动更新会在错误的一侧创建单向连接

Question

问题是，当我运行应用程序时，hibernate 在 tahograph_cards 表中创建了我不想要的列 user_id，并且它不会在我想要的 users 表中创建列 tahograph_card_id 。这是一个 OneToMany 关系。

这是我的文件:

应用程序属性:

spring.datasource.url=jdbc:mysql://127.0.0.1:3306/getmydrivercard
spring.datasource.username=root
spring.datasource.password=root
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.jpa.generate-ddl=true
spring.jpa.hibernate.ddl-auto = update

用户:

package com.getmydrivercard.getmydrivercard.models;

import com.fasterxml.jackson.annotation.JsonIgnore;
import org.hibernate.annotations.GenericGenerator;
import org.hibernate.annotations.OnDelete;
import org.hibernate.annotations.OnDeleteAction;

import javax.persistence.*;
import javax.validation.constraints.NotEmpty;
import java.util.HashSet;
import java.util.Set;
import java.util.UUID;

@Entity
@Table(name = "users")
public class User {
    private static final String EMPTY_STRING = "";

    @Id
    @GeneratedValue(generator = "uuid2")
    @GenericGenerator(name = "uuid2", strategy = "uuid2")
    @Column(columnDefinition = "BINARY(16)")
    private UUID userId;

    @NotEmpty
    private String username;

    @NotEmpty
    private String password;

    @NotEmpty
    private String email;


    @OneToMany(fetch = FetchType.LAZY, mappedBy = "user", cascade = CascadeType.ALL)
    @OnDelete(action = OnDeleteAction.CASCADE)
    @JsonIgnore
    private Set<TahographCard> tahographCards;

    private String comments;

    protected User(){}

    public User(String username, String password, String email){
        setUsername(username);
        setPassword(password);
        setEmail(email);
        setComments(EMPTY_STRING);
        setTahographCards();
    }

   //getters and setters
}

行车记录仪卡:

package com.getmydrivercard.getmydrivercard.models;

import org.hibernate.annotations.GenericGenerator;

import javax.persistence.*;
import javax.validation.constraints.NotEmpty;
import java.util.UUID;

@Entity
@Table(name = "tahograph_cards")
public class TahographCard {
    @Id
    @GeneratedValue(generator = "uuid2")
    @GenericGenerator(name = "uuid2", strategy = "uuid2")
    @Column(columnDefinition = "BINARY(16)")
    private UUID tahographCardId;

    @NotEmpty
    private Boolean isActive;

    @NotEmpty
    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "userId")
    private User user;

    protected TahographCard(){}

    public TahographCard(User user){
        setUser(user);
        setActive(true);
    }
    //getters and setters
  }

我尝试使用mappedBy和我在互联网上找到的其他一些东西，但仍然不起作用。预先感谢您。

Answer 1

这里的问题不是实体配置而是数据库设计。您无法将 oneToMany 关系映射到一侧的 FK 列。

例如，如果您有 2 个用户和 4 个 TahographCard(每个用户 2 个)，通常情况下它会如下所示:

User
id name
1  Foo
2  Bar

Table
id user_id (fk)
1  1
2  1
2  2
2  2

与 User 表上的 TahographCardId 相反是不可能的