我将JPA 2.x
与EclipseLink 2.5.1
和nested primary key class
一起使用,如下所示:-
注意:幕后环境
1. OS: Windows 7 64 Bits
2. JDK: 1.7.0_65 64 Bits
3. Maven: 3.2.2
4. Arquillian: 1.1.5.Final
5. Container: Glassfish 4 embedded
6. Database: Derby 10.10.2.0 embedded
大师PK
@Embeddable
public class MasterPk {
@Column(
name = "MASTER_ID",
length = 5
)
private String masterId;
//----> Setter/Getter is omitted
}
大师
@Entity
@Table(name = "MASTER_TAB")
public class Master {
@EmbeddedId
private MaskerPk id;
@Column(
name = "MASTER_NAME",
length = 40
)
private String masterName;
@OneToMany(
mappedBy = "master"
)
private List<Detail> details;
//----> Setter/Getter is omitted
}
细节PK
@Embeddable
public class DetailPk {
//----> THE NESTED IS HERE.
@Embedded
private MasterPk masterId;
@Column(
name = "DETAIL_ID",
length = 5
)
private String detailId;
//----> Setter/Getter is omitted
}
细节
@Entity
@Table(name = "DETAIL_TAB")
public class Detail {
@EmbeddedId
private DetailPk id;
@Column(
name = "DETAIL_NAME",
length = 40
)
private String detailName;
@MapsId("masterId")
@ManyToOne
@JoinColumns({
@JoinColumn(
name = "MASTER_ID",
referencedColumnName = "MASTER_ID",
nullable = false
)
})
private Master master;
//----> Setter/Getter is omitted
}
持久化细节的编码
MasterPk masterPk = new MasterPk();
masterPk.setId("001"); //there is a 001 existed in the db
DetailPk detailPk = new DetailPk();
detailPk.setMasterId(masterPk);
detailPk.setDetailId("001"); //new detail to persist
Detail detail = new Detail();
detail.id(detailPk);
detail.setDetailName("detail-name");
em.persist(detail);
持久性XML
<persistence xmlns="http://xmlns.jcp.org/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence
http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd"
version="2.1">
<persistence-unit name="unittest" transaction-type="JTA">
<jta-data-source>jdbc/unittest</jta-data-source>
<class>com.test.MasterPk</class>
<class>com.test.Master</class>
<class>com.test.DetiailPk</class>
<class>com.test.Detail</class>
<exclude-unlisted-classes>true</exclude-unlisted-classes>
<properties>
<property name="eclipselink.ddl-generation"
value="create-tables" />
<property name="eclipselink.ddl-generation.output-mode"
value="both"/>
<property name="eclipselink.application-location"
value="target"/>
<property name="eclipselink.create-ddl-jdbc-file-name"
value="createDDL_ddlGeneration.jdbc"/>
<property name="eclipselink.drop-ddl-jdbc-file-name"
value="dropDDL_ddlGeneration.jdbc"/>
</properties>
</persistence-unit>
</persistence>
项目启动时,将正确创建所有表,尤其是
primary key
和foreign key
。但是,当persist
带有编码。时,由于Detail
为空,因此Detail.masterId.id
会有一些麻烦。 EclipseLink
显示我为Column 'MASTER_ID' cannot accept a NULL value.
INSERT INTO DETAIL_TAB (DETAILE_NAME, DETAIL_ID, MASTER_ID)
VALUES (?, ?, ?)
bind => [detail-name, 001, null]
//
//----> We may be noticed that the masterId is not null. It is printed as 001.
//
Query: InsertObjectQuery(Detail(detailName=detail-name,
id=DetailPk(detailId=001,
masterId=(MasterPk(masterId=001))
)
)
)
我通过打印此
field
中的所有object-graph
进行了仔细检查,并可以确认masterId
也不为空。我不确定是否做错了/误解。您能帮忙建议如何解决此问题吗?编辑1
将
@ManyToOne
固定在Detail.java
处。复制并粘贴到此问题时出现错字尝试将
@Embedded
添加到类masterId
的DetailPk
中。编辑1结果仍然面临相同的问题。
编辑2
添加用于创建
detail
和persist
的编码我直接创建
MasterPk
而不找到Master
。进一步的问题,我是否需要找到
Mater
实体以获取其id
并将其分配给DetailPk
而不是直接通过new MasterPk();
创建? 最佳答案
由于MasterPK
是可嵌入的,因此应使用@Embedded
进行注释:
@Embeddable
public class DetailPk {
@Embedded
private MasterPk masterId;
...
}
我猜
Detail
实体也丢失了@ManyToOne
(或者只是故意的?)@Entity
@Table(name = "DETAIL_TAB")
public class Detail {
...
@MapsId("masterId")
@ManyToOne
@JoinColumns({
@JoinColumn(
name = "MASTER_ID",
referencedColumnName = "MASTER_ID",
nullable = false
)
})
private Master master;
}
广告修改2
以下声明
INSERT INTO DETAIL_TAB (DETAILE_NAME, DETAIL_ID, MASTER_ID)
VALUES (?, ?, ?)
bind => [detail-name, 001, null]
表示主从关系的拥有方(由
@ManyToOne
关联表示)为空。从JPA的角度来看,它如下所示:
MASTER_ID
列与master
实体中的Detail
字段相关Master
实体使用MasterPK
作为主键Detail
实体使用Master
字段引用master
因为
Detail
实体充当关系的所有者,所以最好在其上指定级联,即@ManyToOne(cascade = CascadeType.PERSIST)
基于上述,要使事情正常进行,我们需要设置拥有方,例如:
Master master = new Master();
master.id(masterPk);
Detail detail = new Detail();
detail.id(detailPk);
detail.setMaster(master); // the owning side of the master-detail relationship
master.setDetail(detail); // mandatory if CascadeType.PERSIST is not defined
em.persist(detail);
这将导致:
INSERT INTO DETAIL_TAB (DETAIL_NAME, DETAIL_ID, MASTER_ID)
VALUES (?, ?, ?)
bind => [detail-name, 001, 001]