Question

我正在尝试使用Hibernate ORM在Employee表中插入记录但是仍然收到错误：

org.hibernate.AssertionFailure: null id in 
com.example.helloworld.entities.Employee entry (don't flush the Session 
after an exception occurs)

如果我传递ID值，那么它可以正常工作但是虽然我使用了@GeneratedValue(strategy = GenerationType.IDENTITY)但它不会自动生成'id'。任何帮助表示赞赏！有关DB模式和实体代码的详细信息如下所示。

数据库引擎：Postgres

ORM：Hibernate

我有以下两个表：

表名员工：

Column Name |  Type      |  Length    |  Not Null  | Default
name        | Varchar    |  64        |  true      | NULL 
id          |  int8      |  19        |  true      |nextval(Employee_id::regclass)
company_id  |  int8     |19           |  true      | NULL

表#Company

Column Name |  Type      |  Length    |  Not Null  | Default
Cname       | Varchar    |  64        |  true      | NULL 
id          |  int8      |  19        |  true      | nextval(Company_id::regclass)

 area       |  varchar    |64          |  true      | NULL

上表的实体Java类：

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

    public Employee() {super();}

    @Id
    @Column(name = "id", columnDefinition = "serial")
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @NotNull
    private long id;

    @NotNull
    @Column(name = "company_id")
    private long company_id;

    @NotNull
    @Column(name = "name")
    private String name;

    @ManyToOne
    private Company company;

   /**
   setters and getters
   **/
}

@Entity
@Table(name = "Company")
public class Company {

    public Company() {super();}

    @Id
    @Column(name = "id", columnDefinition = "serial")
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @NotNull
    private long id;

    @NotNull
    @Column(name = "area")
    private String area;

    @NotNull
    @Column(name = "cname")
    private String cname;

    @OneToMany(cascade=CascadeType.ALL)
    @JoinColumn(name="company_id")
    private Set<Employee> employees;

   /**
   setters and getters
   **/
}

Answer 1

我和Postgres有同样的问题。尝试在SequenceGenerator字段中添加id：

@Id
@Column(name = "id", columnDefinition = "serial")
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator="SEQ_EMPLOYEE")
@SequenceGenerator(name="SEQ_EMPLOYEE", sequenceName="SEQ_EMPLOYEE", allocationSize=1)
@NotNull
private long id;

将SEQ_EMPLOYEE替换为数据库中序列的名称。

Answer 2

这对我有用：

@Id
@Column(name = "id", columnDefinition = "serial")
@GeneratedValue(strategy = GenerationType.IDENTITY, generator="seq_name_generated_in_db")
@SequenceGenerator(name="seq_name_generated_in_db", sequenceName="seq_name_generated_in_db", initialValue = 1 , allocationSize=1)

Postgres Hibernate主键生成问题

2 个答案: