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Re: [eclipselink-users] EntityManager.find returning instance of wrong type
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If that's what your goal is then your findBarById should look something like:
Object obj = em.find(Bar.class, aId);
if (obj instanceof Bar)
return (Bar) obj;
else
return null;
On Sun, Mar 8, 2009 at 10:57 AM, jsw <marvin.438@xxxxxxxxx> wrote:
>
> I get an id of an entity of either Foo or Bar type as input. So I try to
> determine the type by searching for
> both, like so:
>
> public void doStuff(Long id) {
> Base base = null;
> if ((base = this.facade.getDAO().findFooById(id)) != null) { // this row
> will throw an exception
> log.debug("Found Foo");
> doStuffToFoo((Foo) base);
> } else if ((base = this.facade.getDAO().findBarById(id)) != null) {
> log.debug("Found Bar");
> doStuffToBar((Bar) base);
> }
> }
>
> I don't think the entity manager should ever return an entity of other type
> than the requested. IMHO, if no entity of the requested type exists with the
> specified id, the logical thing to return would be null (or perhaps an
> exception).
>
>
>
> Zarar Siddiqi wrote:
>>
>> Also, just looking at the code sample you provided:
>>
>> Long aId = 76576; // a valid id for an entity of type Bar
>> Foo foo = em.find(Foo.class, aId); // em is EntityManager
>>
>> Why would you not just do the following if you're expecting a Bar object:
>>
>> Bar bar = em.find(Bar.class, aId);
>>
>> ?? I think the ClassCastException that you're getting is the right
>> behaviour.
>>
>>
>>
>> On Sun, Mar 8, 2009 at 10:36 AM, Zarar Siddiqi <zarars@xxxxxxxxx> wrote:
>>> Currently you've got
>>> @Inheritance(strategy=InheritanceType.SINGLE_TABLE) on the subclasses,
>>> try putting them ONLY on the base class.
>>>
>>>
>>>
>>> On Sun, Mar 8, 2009 at 6:50 AM, jsw <marvin.438@xxxxxxxxx> wrote:
>>>>
>>>> If I've understood correctly, when the DiscriminatorColumn annotation is
>>>> missing JPA defaults to DTYPE (with values corresponding to the entity
>>>> name). Just to be sure I tried adding the DiscriminatorColumn annotation
>>>> to
>>>> the Base class and DiscriminatorValue annotations to the subclasses (I
>>>> had
>>>> already moved the Inheritance from the deriving clases to the Base
>>>> class)
>>>> but it made no difference: the problem persists.
>>>>
>>>>
>>>>
>>>> Zarar Siddiqi wrote:
>>>>>
>>>>> How would JPA know what row coincides with what subclass? To tell it
>>>>> that you'll need to use the @DiscriminatorColumn on the parent class
>>>>> and supply a unique value for each subclass using the
>>>>> @DiscriminatorValue for the subclasses.
>>>>>
>>>>> Also, the @Inheritance(strategy=InheritanceType.SINGLE_TABLE)
>>>>> annotation goes on the parent class.
>>>>>
>>>>> Zarar
>>>>>
>>>>>
>>>>> On Fri, Mar 6, 2009 at 8:52 AM, jsw <marvin.438@xxxxxxxxx> wrote:
>>>>>>
>>>>>> In my REST service:
>>>>>>
>>>>>> public void doTest() {
>>>>>> long id = 12; // valid id of Bar entity
>>>>>>
>>>>>> List<Base> bases = this.facade.getDAO().findAllBase();
>>>>>>
>>>>>> Base base = null;
>>>>>> try {
>>>>>> if ((base = this.facade.getWorkOrderDAO().findFooById(id))
>>>>>> !=
>>>>>> null) { // this row will throw an exception
>>>>>> log.debug("Found Foo");
>>>>>> } else if ((base =
>>>>>> this.facade.getWorkOrderDAO().findBarById(id)) != null) {
>>>>>> log.debug("Found Bar");
>>>>>> }
>>>>>>
>>>>>> } catch (Exception ex) {
>>>>>> ex.printStackTrace();
>>>>>> }
>>>>>> }
>>>>>>
>>>>>> And in the DAO class:
>>>>>>
>>>>>> @Transactional(readOnly = true, propagation=Propagation.SUPPORTS)
>>>>>> public List<Base> findAllBase() {
>>>>>> return em.createQuery("select b from Base b").getResultList();
>>>>>> }
>>>>>>
>>>>>> @Transactional(readOnly = true, propagation=Propagation.SUPPORTS)
>>>>>> public Foo findFooById(long id) {
>>>>>> return em.find(Foo.class, id);
>>>>>> }
>>>>>>
>>>>>> @Transactional(readOnly = true, propagation=Propagation.SUPPORTS)
>>>>>> public Bar findBarById(long id) {
>>>>>> return em.find(Bar.class, id);
>>>>>> }
>>>>>>
>>>>>> java.lang.ClassCastException: com.acme.planning.dataaccess.model.Bar
>>>>>> cannot
>>>>>> be cast to com.acme.planning.dataaccess.model.Foo
>>>>>> at com.acme.planning.dataaccess.DAO.findFooById(DAO.java:348)
>>>>>> at
>>>>>> com.acme.planning.dataaccess.DAO$$FastClassByCGLIB$$80c0e135.invoke(<generated>)
>>>>>> at net.sf.cglib.proxy.MethodProxy.invoke(MethodProxy.java:191)
>>>>>> at
>>>>>> org.springframework.aop.framework.Cglib2AopProxy$CglibMethodInvocation.invokeJoinpoint(Cglib2AopProxy.java:700)
>>>>>> at
>>>>>> org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:149)
>>>>>> at
>>>>>> org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:106)
>>>>>> at
>>>>>> org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
>>>>>> at
>>>>>> org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor.intercept(Cglib2AopProxy.java:635)
>>>>>> at
>>>>>> com.acme.planning.dataaccess.DAO$$EnhancerByCGLIB$$93a24725.findFooById(<generated>)
>>>>>> at
>>>>>> com.acme.planning.interaction.rest.MobilogService.test(MobilogService.java:829)
>>>>>> at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
>>>>>> at
>>>>>> sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
>>>>>> at
>>>>>> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
>>>>>> at java.lang.reflect.Method.invoke(Method.java:597)
>>>>>> at
>>>>>> com.sun.jersey.server.impl.model.method.dispatch.EntityParamDispatchProvider$ResponseOutInvoker._dispatch(EntityParamDispatchProvider.java:157)
>>>>>> at
>>>>>> com.sun.jersey.server.impl.model.method.dispatch.ResourceJavaMethodDispatcher.dispatch(ResourceJavaMethodDispatcher.java:67)
>>>>>> at
>>>>>> com.sun.jersey.server.impl.uri.rules.HttpMethodRule.accept(HttpMethodRule.java:154)
>>>>>> at
>>>>>> com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:111)
>>>>>> at
>>>>>> com.sun.jersey.server.impl.uri.rules.ResourceClassRule.accept(ResourceClassRule.java:71)
>>>>>> at
>>>>>> com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:111)
>>>>>> at
>>>>>> com.sun.jersey.server.impl.uri.rules.RootResourceClassesRule.accept(RootResourceClassesRule.java:63)
>>>>>> at
>>>>>> com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:543)
>>>>>> at
>>>>>> com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:502)
>>>>>> at
>>>>>> com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:493)
>>>>>> at
>>>>>> com.sun.jersey.spi.container.servlet.WebComponent.service(WebComponent.java:308)
>>>>>> at
>>>>>> com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:314)
>>>>>> at
>>>>>> com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:239)
>>>>>> at
>>>>>> org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
>>>>>> at
>>>>>> org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
>>>>>> at
>>>>>> com.acme.common.filter.CacheControlFilter.doFilter(CacheControlFilter.java:72)
>>>>>> at
>>>>>> org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
>>>>>> at
>>>>>> org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
>>>>>> at
>>>>>> org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:378)
>>>>>> at
>>>>>> org.springframework.security.intercept.web.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:109)
>>>>>> at
>>>>>> org.springframework.security.intercept.web.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:83)
>>>>>> at
>>>>>> org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:390)
>>>>>> at
>>>>>> org.springframework.security.ui.SessionFixationProtectionFilter.doFilterHttp(SessionFixationProtectionFilter.java:67)
>>>>>> at
>>>>>> org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53)
>>>>>> at
>>>>>> org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:390)
>>>>>> at
>>>>>> org.springframework.security.ui.ExceptionTranslationFilter.doFilterHttp(ExceptionTranslationFilter.java:101)
>>>>>> at
>>>>>> org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53)
>>>>>> at
>>>>>> org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:390)
>>>>>> at
>>>>>> org.springframework.security.providers.anonymous.AnonymousProcessingFilter.doFilterHttp(AnonymousProcessingFilter.java:105)
>>>>>> at
>>>>>> org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53)
>>>>>> at
>>>>>> org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:390)
>>>>>> at
>>>>>> org.springframework.security.wrapper.SecurityContextHolderAwareRequestFilter.doFilterHttp(SecurityContextHolderAwareRequestFilter.java:91)
>>>>>> at
>>>>>> org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53)
>>>>>> at
>>>>>> org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:390)
>>>>>> at
>>>>>> org.springframework.security.ui.basicauth.BasicProcessingFilter.doFilterHttp(BasicProcessingFilter.java:174)
>>>>>> at
>>>>>> org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53)
>>>>>> at
>>>>>> org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:390)
>>>>>> at
>>>>>> org.springframework.security.ui.AbstractProcessingFilter.doFilterHttp(AbstractProcessingFilter.java:277)
>>>>>> at
>>>>>> org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53)
>>>>>> at
>>>>>> org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:390)
>>>>>> at
>>>>>> org.springframework.security.ui.logout.LogoutFilter.doFilterHttp(LogoutFilter.java:89)
>>>>>> at
>>>>>> org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53)
>>>>>> at
>>>>>> org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:390)
>>>>>> at
>>>>>> org.springframework.security.context.HttpSessionContextIntegrationFilter.doFilterHttp(HttpSessionContextIntegrationFilter.java:235)
>>>>>> at
>>>>>> org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53)
>>>>>> at
>>>>>> org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:390)
>>>>>> at
>>>>>> org.springframework.security.util.FilterChainProxy.doFilter(FilterChainProxy.java:175)
>>>>>> at
>>>>>> org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:236)
>>>>>> at
>>>>>> org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:167)
>>>>>> at
>>>>>> org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
>>>>>> at
>>>>>> org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
>>>>>> at
>>>>>> org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:96)
>>>>>> at
>>>>>> org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
>>>>>> at
>>>>>> org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
>>>>>> at
>>>>>> org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
>>>>>> at
>>>>>> org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)
>>>>>> at
>>>>>> org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
>>>>>> at
>>>>>> org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
>>>>>> at
>>>>>> org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:230)
>>>>>> at
>>>>>> org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
>>>>>> at
>>>>>> org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:179)
>>>>>> at
>>>>>> org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:84)
>>>>>> at
>>>>>> org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
>>>>>> at
>>>>>> org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
>>>>>> at
>>>>>> org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:157)
>>>>>> at
>>>>>> org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
>>>>>> at
>>>>>> org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:262)
>>>>>> at
>>>>>> org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
>>>>>> at
>>>>>> org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
>>>>>> at
>>>>>> org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:446)
>>>>>> at java.lang.Thread.run(Thread.java:619)
>>>>>>
>>>>>>
>>>>>> tch wrote:
>>>>>>>
>>>>>>> Doesn't sound right, can you post the whole stack trace?
>>>>>>>
>>>>>>> ./tch
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On Fri, Mar 6, 2009 at 7:56 AM, jsw <marvin.438@xxxxxxxxx> wrote:
>>>>>>>>
>>>>>>>> OK, thank you, it seems I had misunderstood how to use the
>>>>>>>> @Inheritance
>>>>>>>> annotation. However, in this case it does not seem to make a
>>>>>>>> difference
>>>>>>>> since SINGLE_TABLE is the default inheritance type.
>>>>>>>>
>>>>>>>> Unfortunately, moving the @Inherintance annotation to the base class
>>>>>>>> did
>>>>>>>> not
>>>>>>>> solve my problem. EntityManager.find keeps trying to return an
>>>>>>>> instance
>>>>>>>> of
>>>>>>>> the wrong entity.
>>>>>>>>
>>>>>>>> Maybe something more I've misunderstood?
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> tch wrote:
>>>>>>>>>
>>>>>>>>> I've never used the @Inheritance annotation, but I believe it goes
>>>>>>>>> on
>>>>>>>>> the base class, not the extending entity.
>>>>>>>>>
>>>>>>>>> See:
>>>>>>>>> http://www.oracle.com/technology/products/ias/toplink/jpa/howto/use-inheritance.html
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On Fri, Mar 6, 2009 at 3:00 AM, jsw <marvin.438@xxxxxxxxx> wrote:
>>>>>>>>>>
>>>>>>>>>> Environment: JBoss, Jersey, Spring, EclipseLink JPA, PostgreSQL
>>>>>>>>>>
>>>>>>>>>> @Entity
>>>>>>>>>> public abstract class Base {
>>>>>>>>>> @Id
>>>>>>>>>> @GeneratedValue(strategy = GenerationType.TABLE)
>>>>>>>>>> private Long id;
>>>>>>>>>>
>>>>>>>>>> @Version
>>>>>>>>>> private long version;
>>>>>>>>>>
>>>>>>>>>> ...
>>>>>>>>>> }
>>>>>>>>>>
>>>>>>>>>> @Entity
>>>>>>>>>> @Inheritance(strategy=InheritanceType.SINGLE_TABLE)
>>>>>>>>>> public class Foo extends Base { ... }
>>>>>>>>>>
>>>>>>>>>> @Entity
>>>>>>>>>> @Inheritance(strategy=InheritanceType.SINGLE_TABLE)
>>>>>>>>>> public class Bar extends Base { ... }
>>>>>>>>>>
>>>>>>>>>> Then when I do:
>>>>>>>>>>
>>>>>>>>>> Long aId = 76576; // a valid id for an entity of type Bar
>>>>>>>>>> Foo foo = em.find(Foo.class, aId); // em is EntityManager
>>>>>>>>>>
>>>>>>>>>> an exception is thrown (the root cause seems to be
>>>>>>>>>> ClassCastException)
>>>>>>>>>> because the EntityManager tries to return an object of type Bar.
>>>>>>>>>>
>>>>>>>>>> What am I doing wrong?
>>>>>>>>>> --
>>>>>>>>>> View this message in context:
>>>>>>>>>> http://www.nabble.com/EntityManager.find-returning-instance-of-wrong-type-tp22367490p22367490.html
>>>>>>>>>> Sent from the EclipseLink - Users mailing list archive at
>>>>>>>>>> Nabble.com.
>>>>>>>>>>
>>>>>>>>>> _______________________________________________
>>>>>>>>>> eclipselink-users mailing list
>>>>>>>>>> eclipselink-users@xxxxxxxxxxx
>>>>>>>>>> https://dev.eclipse.org/mailman/listinfo/eclipselink-users
>>>>>>>>>>
>>>>>>>>> _______________________________________________
>>>>>>>>> eclipselink-users mailing list
>>>>>>>>> eclipselink-users@xxxxxxxxxxx
>>>>>>>>> https://dev.eclipse.org/mailman/listinfo/eclipselink-users
>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>> --
>>>>>>>> View this message in context:
>>>>>>>> http://www.nabble.com/EntityManager.find-returning-instance-of-wrong-type-tp22367490p22371962.html
>>>>>>>> Sent from the EclipseLink - Users mailing list archive at
>>>>>>>> Nabble.com.
>>>>>>>>
>>>>>>>> _______________________________________________
>>>>>>>> eclipselink-users mailing list
>>>>>>>> eclipselink-users@xxxxxxxxxxx
>>>>>>>> https://dev.eclipse.org/mailman/listinfo/eclipselink-users
>>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> eclipselink-users mailing list
>>>>>>> eclipselink-users@xxxxxxxxxxx
>>>>>>> https://dev.eclipse.org/mailman/listinfo/eclipselink-users
>>>>>>>
>>>>>>>
>>>>>>
>>>>>> --
>>>>>> View this message in context:
>>>>>> http://www.nabble.com/EntityManager.find-returning-instance-of-wrong-type-tp22367490p22372894.html
>>>>>> Sent from the EclipseLink - Users mailing list archive at Nabble.com.
>>>>>>
>>>>>> _______________________________________________
>>>>>> eclipselink-users mailing list
>>>>>> eclipselink-users@xxxxxxxxxxx
>>>>>> https://dev.eclipse.org/mailman/listinfo/eclipselink-users
>>>>>>
>>>>> _______________________________________________
>>>>> eclipselink-users mailing list
>>>>> eclipselink-users@xxxxxxxxxxx
>>>>> https://dev.eclipse.org/mailman/listinfo/eclipselink-users
>>>>>
>>>>>
>>>>
>>>> --
>>>> View this message in context:
>>>> http://www.nabble.com/EntityManager.find-returning-instance-of-wrong-type-tp22367490p22396645.html
>>>> Sent from the EclipseLink - Users mailing list archive at Nabble.com.
>>>>
>>>> _______________________________________________
>>>> eclipselink-users mailing list
>>>> eclipselink-users@xxxxxxxxxxx
>>>> https://dev.eclipse.org/mailman/listinfo/eclipselink-users
>>>>
>>>
>> _______________________________________________
>> eclipselink-users mailing list
>> eclipselink-users@xxxxxxxxxxx
>> https://dev.eclipse.org/mailman/listinfo/eclipselink-users
>>
>>
>
> --
> View this message in context: http://www.nabble.com/EntityManager.find-returning-instance-of-wrong-type-tp22367490p22398821.html
> Sent from the EclipseLink - Users mailing list archive at Nabble.com.
>
> _______________________________________________
> eclipselink-users mailing list
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