我使用的是 Hibernate 4.1.0.Final、JPA 2.0 和 MySQL 5.5。我有以下实体:
@GenericGenerator(name = "uuid-strategy", strategy = "uuid.hex")
@Entity
@Table(name = "cb_organization", uniqueConstraints = {@UniqueConstraint(columnNames={"organization_id"})})
public class Organization implements Serializable
{
…
@OneToMany(fetch = FetchType.EAGER, cascade = {CascadeType.PERSIST, CascadeType.MERGE})
@JoinTable(name = "cb_organization_address",
joinColumns = @JoinColumn(name = "organization_id"),
inverseJoinColumns = @JoinColumn(name = "address_id"))
/* List of addresses associated with this organization */
private List<Address> addresses;
注意连接表“cb_organization_address”。它的主键是一个 varchar(32) 非空字段,我希望它是一个 GUID,类似于组织实体的 ID。如何为此表自动生成 ID?当我尝试用地址保存一个组织时,我得到了异常(exception)......
javax.persistence.PersistenceException: org.hibernate.exception.GenericJDBCException: Field 'ID' doesn't have a default value
org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1361)
org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1289)
org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1295)
org.hibernate.ejb.AbstractEntityManagerImpl.flush(AbstractEntityManagerImpl.java:976)
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
java.lang.reflect.Method.invoke(Method.java:597)
org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:240)
$Proxy47.flush(Unknown Source)
org.mainco.subco.organization.repo.OrganizationDaoImpl.save(OrganizationDaoImpl.java:63)
org.mainco.subco.organization.service.OrganizationServiceImpl.save(OrganizationServiceImpl.java:64)
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
java.lang.reflect.Method.invoke(Method.java:597)
org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:318)
org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:183)
org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:110)
org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:202)
$Proxy62.save(Unknown Source)
org.mainco.subco.sbadmin.controllers.OrganizationController.save(OrganizationController.java:204)
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
java.lang.reflect.Method.invoke(Method.java:597)
org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:213)
org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:126)
org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:96)
org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:617)
org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:578)
org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80)
org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:923)
org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:852)
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882)
org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:789)
javax.servlet.http.HttpServlet.service(HttpServlet.java:754)
javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
最佳答案
您不应为连接表自动生成 ID。相反,您应该从 cb_organization_address
中删除 ID 列。 .
联接表通常没有自己的 ID,它们仅表示两件事之间的关联。因此,关系本身的“身份”通常是相关的两个事物的复合键。对于您的用例,我会说这是正确的数据模型:每个组织可以有任何地址零次或一次,每个地址可以在任意数量的组织中。
关于hibernate - 如何为连接表自动生成 GUID?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/13401559/