Spring MVC Hibernate One to One Cascade.ALL merge()问题

Question

使用Spring MVC + Hibernate，我想对Employee实体执行CRUD操作。

employee实体与user实体具有一对一的关系，如下图所示：

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我在更新员工信息时遇到问题。CREATE、READ和DELETE操作运行良好。

但是当我更新员工信息时，它从employee_user表中删除了记录，打破了员工和相应用户之间的关系。

我只有一个JSP页面来保存员工和用户信息。

JSP：

<form:form action="save" method="post" commandName="employee"">
    <div>
        <div>
            <label for="firstName">Name: </label>
            <form:input id="firstName" path="firstName" type="text" />
        </div>
        <div>
            <label for="email">Email: </label>
            <form:input id="email" path="email" type="text" />
        </div>
        <div>
            <label for="phone">Phone: </label>
            <form:input id="phone" path="phone" type="text" />
        </div>

        <div>
            <label for="usernmae">Username: </label>
            <form:input id="username" path="user.username" type="text" />
        </div>
        <div>
            <label for="password">Password: </label>
            <form:input id="password" path="user.password" type="text" />
        </div>
    </div>

    <form:input path="id" type="hidden" />
    <form:input path="user.id" type="hidden" />
    <input type="submit" name="save" value="Save" class="btn btn-primary" />
</form:form>

员工模型如下：

@Entity
@Table(name = "employee")
public class Employee {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    @Column
    private String firstName;

    @Column
    private String email;

    @Column
    private String phone;

    @OneToOne
    @JoinTable(name = "employee_user", joinColumns = { @JoinColumn(name = "employee_id", referencedColumnName = "id") },
        inverseJoinColumns = { @JoinColumn(name = "user_id", referencedColumnName = "id") })
    @Cascade({ org.hibernate.annotations.CascadeType.ALL })
    private User user;

    // getters and setters

}

USER模型是：

@Entity
@Table(name = "user")
public class User {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    @Column
    private String username;

    @Column
    private String password;

    @OneToOne
    @JoinTable(name = "employee_user", joinColumns = { @JoinColumn(name = "user_id", referencedColumnName = "id") },
        inverseJoinColumns = { @JoinColumn(name = "employee_id", referencedColumnName = "id") })
    @Cascade({ org.hibernate.annotations.CascadeType.ALL })
    private Employee employee;

    // getters and setters

}

控制器部分如下所示。相同的方法同时处理创建和更新请求。

@RequestMapping(value = "/save", method = RequestMethod.POST)
public String saveEmployee(@ModelAttribute("employee") Employee employee,
        BindingResult result) {

    employeeService.save(employee);
    return "";
}

在这里，保存方法调用Hibernate的Session.merge(employee);方法。

谁能让我知道幕后的问题是什么？

谢谢！

Answer 1

这个问题的原因是，您的ModelAttribute employee对象将被表单.So中的新值覆盖，对待用户对象为空.you可以通过id从数据库中搜索员工，然后从搜索到的员工.finally中设置用户，合并employee对象。