Question

我设置了一个oneToOne关系时有两个表。 Bill和BillSimpleEntry。（每个Bill都有一个BillSimpleEntry

这是他们的结构

CREATE TABLE `bill` (
  `id` bigint(20) NOT NULL AUTO_INCREMENT,
  ..
  ..
  PRIMARY KEY (`id`),
  UNIQUE KEY `id_UNIQUE` (`id`),
  KEY `fk_bill_groups1_idx` (`groupId`),
  KEY `fk_bill_user1_idx` (`billPayerId`),
  CONSTRAINT `fk_b...` FOREIGN KEY (`groupId`) REFERENCES `groups` (`id`) ON D     ELETE  NO ACTION ON UPDATE NO ACTION,
  CONSTRAINT `fk_b...` FOREIGN KEY (`billPayerId`) REFERENCES `user` (`id`) ON    DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=latin1;
/*!40101 SET character_set_client = @saved_cs_client */;



DROP TABLE IF EXISTS `billsimpleentry`;
/*!40101 SET @saved_cs_client     = @@character_set_client */;
/*!40101 SET character_set_client = utf8 */;
CREATE TABLE `billsimpleentry` (
  `..` varchar(200) DEFAULT NULL,
  `..` text,
  `billId` bigint(20) DEFAULT NULL,
  `id` bigint(20) NOT NULL AUTO_INCREMENT,
  PRIMARY KEY (`id`),
  KEY `fk_bill_idx` (`billId`)
) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=latin1;

JPA config（oneToOne关系属性的账单实体的片段）。

@OneToOne(cascade=CascadeType.ALL,mappedBy="billId",fetch = FetchType.EAGER)
private BillSimpleEntry billSimpleEntry;

我正试图通过billSimpleEntry.billId和bill.Id在Bill和BillSimpleEntry之间进行连接。但我似乎得到了一个错误。

这是我得到的错误 -

Caused by: org.hibernate.AnnotationException: Referenced property not a (One|Many)ToOne:
com.uh.br.domain.BillSimpleEntry.billId in mappedBy of    
com.uh.br.domain.Bill.billSimpleEntryry

以下是实体

Bill.java
@Entity
@Table(name = "bill")
public class Bill implements GenericObject {

/**
 *
 */
private static final long serialVersionUID = -5660869020353250221L;
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)  
private Long id;

...
..
@OneToOne(cascade=CascadeType.ALL,fetch = FetchType.EAGER)
@JoinColumn(name="billId")
private BillSimpleEntry billSimpleEntry;

...
getters & setters
...
}

BillSimpleEntry.java
@Entity
@Table(name="billsimpleentry")
public class BillSimpleEntry  implements GenericObject{

@Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)  
    private Long id;
    private Long billId;
    @Column(columnDefinition="TEXT")
private String itemDescription;//napkin
...
...

    ...
getters & setters
...

Answer 1

mappedBy属性仅对bidirectional关系是必需的，注释上可以省略此元素。它在源实体上用于指向定义关系的目标实体上的字段（包含@JoinColumn）。

@JoinColumn注释应放在billSimpleEntry字段上，以定义应该用于连接两个表的列。在OneToOne的情况下，以下情况适用：

如果连接是使用外键进行OneToOne或ManyToOne映射的映射策略，外键列在源表中实体或可嵌入的。

这是一个代码示例：

@OneToOne(cascade=CascadeType.ALL,fetch = FetchType.EAGER)
@JoinColumn(name="id")
private BillSimpleEntry billSimpleEntry;

此外，如果Bill将包含SimpleBillEntry字段，则BILL表应包含billsimpleentry表的外键。

与OneToOne mappedBy注释的JPA（Hibernate）问题

1 个答案: