[英]@OneToOne relationship with JPA
我正在为我的大学进行一个项目。 这是像AirBnb这样的预订系统。 系统内部有两个实体:请求和结构。 没有相关请求,无法插入结构。 因此,我以这种方式对请求建模:
public class Request {
//...attributes (with a Generated Id)..//
@OneToOne(optional=false)
@JoinColumn(
name="structure_id", unique=true, nullable=false, updatable=false)
private Structure structure;
}
和结构:
public class Structure{
//...attributes (with a Generated Id)..//
private Request request;
@OneToOne(optional=false, mappedBy="structure")
public Request getRequest() {
return request;
}
每次我尝试测试该应用程序时,它在
Persistence.createEntityManagerFactory()
出现此错误消息:
Stacktrace:]的根本原因是org.hibernate.MappingException:无法确定以下类型:it.ispw.efco.nottitranquille.model.Structure,在表:Request处,用于列:[org.hibernate.mapping.Column(structure)]在org.hibernate.mapping.SimpleValue.getType(SimpleValue.java:396)在org.hibernate.mapping.SimpleValue.isValid(SimpleValue.java:369)在org.hibernate.mapping.Property.isValid(Property.java:225) )的org.hibernate.boot.internal.MetadataImpl.validate(MetadataImpl。)的org.hibernate.mapping.RootClass.validate(RootClass.java:265)的org.hibernate.mapping.PersistentClass.validate(PersistentClass.java:529) org.hibernate.boot.internal.SessionFactoryBuilderImpl.build(SessionFactoryBuilderImpl.java:443)上的org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:879)上的org.hibernate.jpa .HibernatePersistenceProvider.createEntityManagerFactory(HibernatePersistenceProvider.java:58)在javax.persistence.Persistence.createEntityMana gerFactory(Persistence.java:55)位于javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:39)位于it.ispw.efco.nottitranquille.model.JPAInitializer。(JPAInitializer.java:25)位于it.ispw.efco。在it.ispw.efco.nottitranquille.model.CatalogueDAO.saveRequest(CatalogueDAO.java:26)上的nottitranquille.model.JPAInitializer.getEntityManager(JPAInitializer.java:43)在it.ispw.efco.nottitranquille.view.SearchBean.validate( org.apache.jsp.search_jsp._jspService(search_jsp.java:134)的SearchBean.java:79)org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)的javax.servlet.http.HttpServlet org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396)上的org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:438)上的.service(HttpServlet.java:729) org.apache.catalina.core.ApplicationFilterChain.internalDoFilt上的javax.servlet.http.HttpServlet.service(HttpServlet.java:729)上的apache.jasper.servlet.JspServlet.service(JspServlet.java:340) er(ApplicationFilterChain.java:291)(位于org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)(位于org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)) org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)处的.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)在org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve .java:219)位于org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)位于org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)位于org.apache.catalina。 org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)处的core.StandardHostValve.invoke(StandardHostValve.java:142)在org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:617)在org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)上 t org.apache.coyote.http11上的org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:518)org.apache.coyote.AbstractProtocol $ AbstractConnectionHandler.process上的org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1091) (AbstractProtocol.java:668)在org.apache.tomcat.util.net.NioEndpoint $ SocketProcessor.doRun(NioEndpoint.java:1521)在org.apache.tomcat.util.net.NioEndpoint $ SocketProcessor.run(NioEndpoint.java :1478),位于java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145),位于org.apache.tomcat.util.threads处的java.util.concurrent.ThreadPoolExecutor $ Worker.run(ThreadPoolExecutor.java:615)。 TaskThread $ WrappingRunnable.run(TaskThread.java:61)位于java.lang.Thread.run(Thread.java:745)
无法在数据库内部映射这种关系? (Windows 10上为MySQL 5.7.10)如果没有结构,请求将无法生存,反之亦然。 我该如何解决? 提前非常感谢您!
编辑1:我现在收到此新错误:
org.hibernate.TransientPropertyValueException:对象引用了一个未保存的瞬态实例-在刷新之前保存该瞬态实例:it.ispw.efco.nottitranquille.model.Structure.request-> it.ispw.efco.nottitranquille.model.Request
这个代码正确吗? 请求应该保存与其链接的结构,对吗?
Address address = new Address(//some fields//);
Structure structure = new Structure(/*a name*/,address);
Request request = new Request(structure);
CatalogueDAO catalogueDAO = new CatalogueDAO();
catalogueDAO.saveRequest(request);
编辑2:
通过在Request.structure的@OneToOne上添加(cascade = CascadeType.ALL)
解决了先前的问题
但是现在我得到了:
不能添加或更新子行,外键约束失败(
notti_tranquille
。request
,约束FKbi1rasm9sdgrouh2mdklvi2q
外键(id
)参考structure
(address_id
))
结构具有另一个属性:地址,具有自己的ID和简单属性
@OneToOne @MapsId
private Address address;
但是,如果检查由JPA创建的表,我会看到该表结构具有作为主键的address_id ...为什么?
为什么在getRequest()上方添加注释? 试试这个
public class Structure{
//...attributes (with a Generated Id)..//
@OneToOne(optional=false, mappedBy="structure")
private Request request;
public Request getRequest() {
return request;
}
您是否尝试删除此注释@JoinColumn(name =“ structure_id”,unique = true,nullable = false,updatable = false)。 在这里您可以找到工作示例一对一示例
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