JPA ConstraintViolation异常forgein键作为值null

Question

我用HiberNate迁移到JPA持久化。我用两个实体进行测试，当持久化一个实体时，我会收到forgein键的值为空的约束违反的异常。

这是数据库表的结构：

CREATE TABLE AZIENDA
(AZN_ID INTEGER NOT NULL PRIMARY KEY GENERATED ALWAYS AS IDENTITY (START WITH 1, INCREMENT BY 1),
...

CREATE TABLE AGENTE
(AGN_ID INTEGER NOT NULL PRIMARY KEY GENERATED ALWAYS AS IDENTITY (START WITH 1, INCREMENT BY 1),
    AGN_IDAZN INTEGER NOT NULL,
...
CONSTRAINT FK_AGN_AZN FOREIGN KEY (AGN_IDAZN) REFERENCES AZIENDA (AZN_ID) ON DELETE CASCADE);

实体：

@Entity
@Table(name="AZIENDA")
public class Azienda {    
    @Column(name="AZN_ID")    
    @Id @GeneratedValue(strategy=GenerationType.IDENTITY)
    private Integer id;
...
@Entity
@Table(name="AGENTE")
public class Agente {   
    @Column(name="AGN_ID")    
    @Id @GeneratedValue(strategy=GenerationType.IDENTITY)
    private Integer id;

    @Column(name="AGN_IDAZN")
    @JoinColumn(name="FK_AGN_AZN", referencedColumnName="AZN_ID")
    @ManyToOne()
    // @ManyToOne(optional=true, cascade=CascadeType.PERSIST)
    @Transient
    private Azienda azienda;
...

首先从数据库中检索对象'Azienda'，实例后一个新的'Agente'实体，并设置属性'azienda'，当创建和持久化一个新的实体'Agente'时，我收到ConstraintViolationExcpetion列'AGN_IDAZN'不能包含值null，但实例'Azienda'not是null。

谢谢

Answer 1

我以另一种方式实现了@Transient annotation的功能。。。谢谢

这是实体更改：

@Entity
@Table(name="AGENTE")
public class Agente {   

    ...

    @JoinColumn(name="AGN_IDAZN", referencedColumnName="AZN_ID")
    @ManyToOne(cascade=CascadeType.PERSIST)
    private Azienda azienda;

    ...
 }

Answer 2

尝试从Agente类的azienda属性中删除@Transient注释。

@Transient注释意味着实体字段是不参与持久化的字段，它们的值永远不会存储在数据库中。