java - 如何通过加入来持久化实体？

Question

我对如何使用列的连接在数据库中保存条目感到困惑。我有@Entity 波纹管

@XmlRootElement
@XmlAccessorType(value = XmlAccessType.FIELD)
@Entity
@Table(name = "psc_users")
@NamedQuery(name = "User.findAll", query = "SELECT u FROM User u")
public class User implements Serializable {
    private static final long serialVersionUID = 8885916014620036457L;

    @Id
    private static final String SEQUENCE_NAME = "psc_users_user_id_seq";
    @Id
    @GeneratedValue(generator = "UseExistingOrGenerateIdGenerator",
            strategy = GenerationType.SEQUENCE)
    @GenericGenerator(name = "UseExistingOrGenerateIdGenerator",
            strategy = "com.psc.util.UseExistingOrGenerateIdGenerator",
            parameters = {
                    @org.hibernate.annotations.Parameter(name = "sequence", value = SEQUENCE_NAME)
            }
    )
    @Column(name = "USER_ID")
    private Long userId;

    @Column(name = "DEF", length = 30)
    private String def;

    @Temporal(TemporalType.TIMESTAMP)
    @Column(name = "DEL_DATE")
    private Date delDate;

    @Column(name = "DISPLAY_DEF", length = 60)
    private String displayDef;

    @Column(name = "EMAIL", length = 60)
    private String email;

    @Temporal(TemporalType.TIMESTAMP)
    @Column(name = "NAVI_DATE")
    private Date naviDate;

    @Column(name = "NAVI_USER")
    private String naviUser;

    @Column(name = "PHONE", length = 30)
    private String phone;

    @Column(name = "PWD", length = 40)
    private String pwd;

    //bi-directional many-to-one association to Branch
    @ManyToOne(cascade = CascadeType.MERGE)
    @JoinColumn(name = "BRNC_BRNC_ID", nullable = false)
    private Branch pscBranch;

    public Long getBrncBrncId() {
        return brncBrncId;
    }

    public void setBrncBrncId(Long brncBrncId) {
        this.brncBrncId = brncBrncId;
    }

    @Column(name = "BRNC_BRNC_ID", insertable = false, updatable = false)
    private Long brncBrncId;
    //bi-directional many-to-one association to User
    @ManyToOne(cascade = CascadeType.MERGE)
    @JoinColumn(name = "CURATOR_USER_ID")
    private User pscUser;


    public Long getCuratorUserId() {
        return curatorUserId;
    }

    public void setCuratorUserId(Long curatorUserId) {
        this.curatorUserId = curatorUserId;
    }

    @Column(name = "CURATOR_USER_ID", insertable = false, updatable = false)
    private Long curatorUserId;

    public User() {
    }

    public Long getUserId() {
        return this.userId;
    }

    public void setUserId(Long userId) {
        this.userId = userId;
    }

    public String getDef() {
        return this.def;
    }

    public void setDef(String def) {
        this.def = def;
    }

    public Date getDelDate() {
        return this.delDate;
    }

    public void setDelDate(Date delDate) {
        this.delDate = delDate;
    }

    public String getDisplayDef() {
        return this.displayDef;
    }

    public void setDisplayDef(String displayDef) {
        this.displayDef = displayDef;
    }

    public String getEmail() {
        return this.email;
    }

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

    public Date getNaviDate() {
        return this.naviDate;
    }

    public void setNaviDate(Date naviDate) {
        this.naviDate = naviDate;
    }

    public String getNaviUser() {
        return this.naviUser;
    }

    public void setNaviUser(String naviUser) {
        this.naviUser = naviUser;
    }

    public String getPhone() {
        return this.phone;
    }

    public void setPhone(String phone) {
        this.phone = phone;
    }

    public String getPwd() {
        return this.pwd;
    }

    public void setPwd(String pwd) {
        this.pwd = pwd;
    }

    public Branch getPscBranch() {
        return this.pscBranch;
    }

    public void setPscBranch(Branch pscBranch) {
        this.pscBranch = pscBranch;
    }

    public User getPscUser() {
        return this.pscUser;
    }

    public void setPscUser(User pscUser) {
        this.pscUser = pscUser;
    }

}

如果我保存没有字段 pscUser 的用户实例(此处为空)，但存在具有正确值的有效 CuratorUserId，我最终会遇到数据库中 CuratorUserId 为空的情况。如果您查看代码，就会看到这些绑定(bind)字段。

  @ManyToOne(cascade = CascadeType.MERGE)
    @JoinColumn(name = "CURATOR_USER_ID")
    private User pscUser;


    @Column(name = "CURATOR_USER_ID", insertable = false, updatable = false)
    private Long curatorUserId;

保存用户的代码

repositoryUser.save(user);

这是我在调试器中看到的

这是我在保存用户后在数据库中看到的。

抱歉我提出了愚蠢的问题，但我遇到了不同的行为，我的项目中有代码以另一种方式运行。我不想搜索实际的另一个用户(策展人)来保存我的用户，因为查询开销

Answer 1

curetorUserId 字段上的@Column 注解有属性insertable=false 和 updatable=false，这意味着它的值在插入和更新期间被忽略。

您可以将这些属性更改为 true(但它可能会在其他一些地方破坏您的应用程序)或仅使用 EntityManager.getReference 填写 pscUser 字段，这只会创建一个代理，实际上不会产生对数据库的查询.