java - 仅在保存实体时制作 transient 列

Question

我有下一个情况。我有实体对象 User:

package models;

import java.util.Date;
import java.util.HashSet;
import java.util.Set;

import javax.persistence.*;

import org.hibernate.annotations.Proxy;


@Entity
@Table(name="users")
@Proxy(lazy=true)
public class User {

    private int id;
    private String login;
    private String password;
    private String name;
    private String email;
    private Integer age;
    private String country;
    private Set<UserRole> roles = new HashSet<UserRole>();
    private UserStatus status;
    private Date created;
    private Date updated;

    public User() {
        status=UserStatus.A;
    }

    public User(String user_login, String user_password, String user_name, String user_email) {
        this.login = user_login;
        this.password = user_password;
        this.name = user_name;
        this.email = user_email;
        status=UserStatus.A;
    }

    public User(String user_login, String user_password, String user_name, String user_email, int age) {
        this(user_login, user_password, user_name, user_email);
        this.age = age;
    }

    public User(String user_login, String user_password, String user_name, String user_email, int age, String country) {
        this(user_login, user_password, user_name, user_email, age);
        this.country = country;
    }

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name="user_id", unique = true)
    public int getId() {
        return id;
    }

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

    @Column(name="user_login")
    public String getLogin() {
        return login;
    }

    public void setLogin(String user_login) {
        this.login = user_login;
    }

    @Column(name="user_password")
    public String getPassword() {
        return password;
    }

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

    @Column(name="user_name")
    public String getName() {
        return name;
    }

    public void setName(String user_name) {
        this.name = user_name;
    }

    @Column(name="user_email")
    public String getEmail() {
        return email;
    }

    public void setEmail(String user_email) {
        this.email = user_email;
    }

    @Column(name="user_age")
    public Integer getAge() {
        return age;
    }

    public void setAge(Integer user_age) {
        this.age = user_age;
    }

    @Column(name="user_country")
    public String getCountry() {
        return country;
    }

    public void setCountry(String user_country) {
        this.country = user_country;
    }

    @ManyToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
    @JoinTable(name = "users_to_userroles", joinColumns = { @JoinColumn(name = "user_id") }, 
                                            inverseJoinColumns = { @JoinColumn(name = "user_role_id ") })
    public Set<UserRole> getRoles() {
        return roles;
    }

    public void setRoles(Set<UserRole> user_roles) {
        this.roles = user_roles;
    }

    @Column(name="user_status")
    @Enumerated(EnumType.STRING)
    public UserStatus getStatus() {
        return status;
    }

    public void setStatus(UserStatus status) {
        this.status = status;
    }

    @Transient
    @Column(name="user_created")
    public Date getCreated() {
        return created;
    }

    public void setCreated(Date user_created) {
        this.created = user_created;
    }

    @Transient
    @Column(name="user_updated")
    public Date getUpdated() {
        return updated;
    }

    public void setUpdated(Date user_updated) {
        this.updated = user_updated;
    }

}

和 JSP 页面(简单的形式，与问题无关)使用创建新用户的表单和显示所有现有用户的表。我在表单和实体对象 User 之间使用了绑定(bind)(它在 Controller 内部):

User user = new User();
 List<User> users = userService.getAllUsers();//to fill table with users
 List<UserRole> userRoles = userRolesService.getAllRoles();//to fill tables with users

 model.addAttribute("rolesList", userRoles);
 model.addAttribute("users", users);
 model.put("adminForm", user);//Here adminForm is the name of form in JSP page

现在问题是什么:如您所见，User 有两个字段 user_created 和 user_updated(它们由 Postgres 服务器自动创建)。它们与所有其他字段一起转发到 JSP 页面中的表。但是我在 JSP 中的表单不提供这些字段(不需要 - 对))))，因此当从表单传输到 Controller 时它们为空。现在 Hibernate 无法在 Postgres 服务器上添加行，因为两个字段为空(((所以我的问题是:我能以某种方式将这些列标记为 @Transient 但只有当我保存实体而不是从数据库中读取它时。我知道我仍然可以绑定(bind)单独的字段而不是整个对象。但是仍然可以按照我的要求做吗？使用现有配置，新的User 已保存，但未读取这两个字段且 JSP 表列为空(((

Answer 1

您需要将列映射的insertable 和updatable 属性设置为false。这将使该字段对于 Hibernate 为只读。

@Column(name="user_created", insertable=false, updatable=false)