org.hibernate.MappingException：实体映射中的重复列

Question

我有两个域模型：“UserBean”和“LoginBean”。这是一对多的关系，用户有很多登录记录。 LoginBean.userid是UserBean.id的外键。 这里是数据库的DDL：

CREATE TABLE `users` (
    `id` int(11) NOT NULL, 
    `username` varchar(255) DEFAULT NULL, 
    `password` varchar(255) DEFAULT NULL, 
    `register_date` datetime DEFAULT NULL, 
    PRIMARY KEY (`id`) 
)

CREATE TABLE `login` (
    `id` int(11) NOT NULL, 
    `user_id` int(11) NOT NULL, 
    `login_date` datetime NOT NULL, 
    `login_result` char(1) NOT NULL, 
    PRIMARY KEY (`id`), 
    KEY `user_id` (`user_id`), 
    CONSTRAINT `login_ibfk_1` FOREIGN KEY (`user_id`) REFERENCES `users` (`id`) 
)

 

    @Entity 
    @Table(name = "login") 
    public class LoginBean { 
     @Id 
     @Column(name = "id", nullable = false) 
     @GenericGenerator(name = "ddd", strategy = "increment") 
     @GeneratedValue(generator = "ddd") 
     private Integer id; //PK 

     // FK --> user.id 
     @Column(name = "user_id", nullable = false) 
     private Integer userid; 

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

     @Column(name = "login_result", nullable = false) 
     private Boolean loginresult; 

     @ManyToOne 
     @ElementCollection(targetClass = fordream.hibernate.bean.UserBean.class) 
     private UserBean user; 

     public Integer getId() { 
      return id; 
     } 

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

     public Integer getUserid() { 
      return userid; 
     } 

     public void setUserid(Integer userid) { 
      this.userid = userid; 
     } 

     public Date getLogindate() { 
      return logindate; 
     } 

     public void setLogindate(Date logindate) { 
      this.logindate = logindate; 
     } 

     public Boolean getLoginresult() { 
      return loginresult; 
     } 

     public void setLoginresult(Boolean loginresult) { 
      this.loginresult = loginresult; 
     } 

     public UserBean getUser() { 
      return user; 
     } 

     public void setUser(UserBean user) { 
      this.user = user; 
     } 
    } 

和：

    @Entity 
    @Table(name = "users") 
    public class UserBean { 
     @Id 
     @GenericGenerator(name = "abc", strategy = "increment") 
     @GeneratedValue(generator = "abc") 
     private Integer id; //PK 

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

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

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

     @OneToMany(mappedBy = "user", cascade = { CascadeType.MERGE }) 
     private Set loginset; 

     public Set getLoginset() { 
      return loginset; 
     } 

     public void setLoginset(Set loginset) { 
      this.loginset = loginset; 
     } 

     public Integer getId() { 
      return id; 
     } 

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

     public String getUsername() { 
      return username; 
     } 

     public void setUsername(String username) { 
      this.username = username; 
     } 

     public String getPassword() { 
      return password; 
     } 

     public void setPassword(String password) { 
      this.password = password; 
     } 

     public Date getRegister_date() { 
      return register_date; 
     } 

     public void setRegister_date(Date register_date) { 
      this.register_date = register_date; 
     } 
    } 

当我运行应用程序，我得到一个消息：Repeated column in mapping for entity: LoginBean column: user_id (should be mapped with insert="false" update="false") 但我检查每一个地方，我从来没有在“LoginBean”中定义了两次“user_id”。 这就是为什么？谢谢 ！

Answer 1

您的映射是双向关联。将你的UserBean作为Parent和LoginBean作为Child。所以，你有2名映射表user_id说明

@Column(name = "user_id", nullable = false) 
    private Integer userid; 

而且

@ManyToOne 
    @ElementCollection(targetClass = fordream.hibernate.bean.UserBean.class) 
    private UserBean user; 

与用户名和USER.ID试图映射到user_id说明。完全删除用户ID字段将为你做，我认为你已经尝试过。

解释：@ManyToOne标签只是说去看看ManyToOne标记的类为关联映射。当它转到UserBean时，它发现LoginBean通过LoginBean的“user”属性关联到UserBean。因此，hibernate会尝试将UserBean的id映射到用户表标记为FK（以db为单位）的LoginBeans字段。

Answer 2

这个错误仅仅是因为你声明了id两次id和getter和setter。 即：在LoginBean类以及UserBean类。如果您将从第二个类中移除该ID，则不会收到错误。您可以编写insertable = false和updateable = false。

private Integer id; // PK

请检查您是否有错误创建了getter和setter。