java - 无法使用 OneToOne 映射保存数据

Question

我正在尝试使用 OneToOne 映射将数据保存在两个表中。我已遵循 this , this , this , this几乎没有更多的在线资源来实现这一点，但它正在抛出

ORA-02291: integrity constraint (TableName.TEST_ID) violated - parent key not found

创建一个表，其中列 TESTID 为外键。在父表中 TESTID 是主键。该主键是使用序列生成器生成的

CREATE TABLE EW_TEST_REFTABLE (
  ID int NOT NULL PRIMARY KEY,
  TESTNAME VARCHAR2(20) NOT NULL,
  TESTID int,
  CONSTRAINT test_id FOREIGN KEY(TESTID)
  REFERENCES EW_TESTDATA(TESTID)
);

Ew_testdataEntity.java(父表实体类)

@Entity
@Table(name = "EW_TESTDATA")
public class Ew_testdata {
    @Id
    @SequenceGenerator(name = "sube_seq",
            sequenceName = "EW_TESTDATA_SEQ",
            allocationSize = 1)
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "sube_seq")

    @Column(name = "TESTID")
    private int testid;

    @Column(name = "TESTNAME")
    private String testname;

    // Ew_test_reftable  is another entity class.In that table the column
    // TESTID (foreign key) must be same as the primary key of this 
    // entity/table(EW_TESTDATA)
    @OneToOne(cascade = CascadeType.ALL)
    @JoinColumn(name = "TESTID",unique = true)
    private Ew_test_reftable ewtestreftable;

       //Constructor
       // getter & setter
    }

Ew_test_reftable.java

@Entity
@Table(name = "EW_TEST_REFTABLE")
public class Ew_test_reftable {

    @Id
    @SequenceGenerator(name = "subf_seq", sequenceName = "EW_REF_SEQ", allocationSize = 1)
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "subf_seq")
    @Column(name = "ID")
    private int id;

    @Column(name = "TESTNAME")
    private String testname;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "TESTID")
    private int testid;
    //Constructor,getter & setter
}

使用Jpa保存数据的服务

@Override
    public Ew_testdata ew_testdata(String name) {

        Ew_test_reftable ew_test_reftable = new Ew_test_reftable();
        ew_test_reftable.setTestname("test");
        Ew_testdata ew_testdata = new Ew_testdata();
        ew_testdata.setTestname(name);
        ew_testdata.setEwtestreftable(ew_test_reftable);
        iew_tEst.ewTestdata(ew_testdata);
        return null;
    }

这个问题似乎与SO中描述的其他一些问题类似，但我仍然无法弄清楚我在哪里犯了错误

Answer 1

您的实体和表结构看起来相反，这使得理解非常困惑。

现在，提到异常

ORA-02291: integrity constraint (TableName.TEST_ID) violated - parent key not found

这意味着，在向子表添加新行时，您在子表中没有父 ID 的引用。

在 Ew_test_reftable 类(class)中，您有

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "TESTID")
private int testid;

如果我理解正确，testid 是您在 EW_TEST_REFTABLE 中的外键，那么您为什么要使用 GenerationType.IDENTITY ？这将创建新的序列 ID，并且可能与父键不匹配并导致错误/异常。

根据我对你的设计的理解，

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "TESTID")
private int testid;

更改为

@OneToOne(cascade = CascadeType.ALL)
@JoinColumn(name = "TESTID",unique = true)
private Ew_testdata ew_testdata;

与上面类似的代码应该从 Ew_testdata 实体中删除(这里和那里可能会有轻微的变化)