如何使用Oracle数据库在jpa批注中自动删除id值？ 如何生成uuid值？

Question

@Entity
@Table(name = "CONTACT_GROUP")
@JsonInclude(JsonInclude.Include.NON_NULL)
public class ContactGroup implements Serializable
{
private static final long serialVersionUID = 7161778136151592279L;
@Id
@GenericGenerator(name = "increment", strategy = "increment")
@GeneratedValue(generator = "increment")
@Column(name = "GRPOUP_ID")
private Long id;

@OneToMany(mappedBy="contactGroup",cascade = { CascadeType.ALL },  targetEntity = Contact.class)
Set<Contact> contacts;
}

@Entity
@Table(name = "CONTACT")
@JsonInclude(JsonInclude.Include.NON_NULL)
public class Contact implements Serializable
{
private static final long serialVersionUID = 7161778136151592279L;
@Id
@GenericGenerator(name = "increment", strategy = "increment")
@GeneratedValue(generator = "increment")
@Column(name = "CONTACT_ID")
Long id;

@GeneratedValue(generator="system-uuid")
@GenericGenerator(name="system-uuid", strategy = "uuid2")
@Column(name="group", unique=true)
String group;

@ManyToOne(cascade={CascadeType.ALL})
@JoinColumn(name = "GRPOUP_ID")
ContactGroup contactGroup;

}

您能告诉我我上面代码中的错误是什么吗？

给出ORA-00001：违反唯一约束

当我一次又一次地运行测试用例时

我如何生成在第一条记录中插入空白vlaue的uuid值

你能告诉我吗，谢谢

Answer 1

由于您正在使用Oracle DB，因此您可以定义并使用Oracle的Sequence来使uuid进行如下操作：

在您的数据库中创建序列，

CREATE SEQUENCE "CONTACT_GROUP_SEQUENCE" 
START WITH 1 
INCREMENT BY 1 -- < here is your "autoincrement" simulation
MAXVALUE 999999999
MINVALUE 1 
NOCACHE 
ORDER

用@SequenceGenerator映射序列，并用它@GenericGenerator

public class ContactGroup implements Serializable
{

@Id
@SequenceGenerator(name = "CONTACT_GROUP_SQ", sequenceName = "CONTACT_GROUP_SEQUENCE", allocationSize = 0)
@GeneratedValue(generator = "CONTACT_GROUP_SQ", strategy = GenerationType.SEQUENCE)
@Column(name = "GRPOUP_ID")
private Long id;
...

在此指向Oracle文档的链接中，找不到有关如何将TableGenerator与Oracle DB一起使用的示例以及其他示例。