Query.getMaxResults not always checked for null result

[trentlarson]

There are many places where Query.getMaxResults is called but not checked for a null value.  This causes my app to crash, for example, when I used the ...List.xhtml view in seam-gen and EntityQuery.nextExists crashed with a NullPointerException on that max value test.

I'm using 2.0.1.GA

(BTW, this is my second submission; I got an error clicking on 'Help' in my first submission.  Erg.)

[trentlarson]

Want me to submit this as a bug?  (There are places where a null has significance, so I expect you'll have to make this check everywhere.)

[pmuir]

Ok, lets see the stack trace.

[trentlarson]

I'll do that, but it's really not relevant because there are many places org/jboss/seam/framework sources that reference 'getMaxResults' without checking for null, and they should all be fixed.

Here 'tis:

Caused by: java.lang.NullPointerException
        at org.jboss.seam.framework.EntityQuery.isNextExists(EntityQuery.java:47)
        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:585)
        at org.jboss.seam.util.Reflections.invoke(Reflections.java:21)
        at org.jboss.seam.intercept.RootInvocationContext.proceed(RootInvocationContext.java:31)
        at org.jboss.seam.intercept.SeamInvocationContext.proceed(SeamInvocationContext.java:56)
        at org.jboss.seam.transaction.RollbackInterceptor.aroundInvoke(RollbackInterceptor.java:31)
        at org.jboss.seam.intercept.SeamInvocationContext.proceed(SeamInvocationContext.java:68)
        at org.jboss.seam.transaction.TransactionInterceptor$1.work(TransactionInterceptor.java:38)
        at org.jboss.seam.util.Work.workInTransaction(Work.java:40)
        at org.jboss.seam.transaction.TransactionInterceptor.aroundInvoke(TransactionInterceptor.java:32)
        at org.jboss.seam.intercept.SeamInvocationContext.proceed(SeamInvocationContext.java:68)
        at org.jboss.seam.core.MethodContextInterceptor.aroundInvoke(MethodContextInterceptor.java:42)
        at org.jboss.seam.intercept.SeamInvocationContext.proceed(SeamInvocationContext.java:68)
        at org.jboss.seam.intercept.RootInterceptor.invoke(RootInterceptor.java:107)
        at org.jboss.seam.intercept.JavaBeanInterceptor.interceptInvocation(JavaBeanInterceptor.java:166)
        at org.jboss.seam.intercept.JavaBeanInterceptor.invoke(JavaBeanInterceptor.java:102)
        at com.icentris.moneplanner.admin.session.ClientList_$$_javassist_2.isNextExists(ClientList_$$_javassist_2.java)
        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:585)
        at javax.el.BeanELResolver.getValue(BeanELResolver.java:62)
        at javax.el.CompositeELResolver.getValue(CompositeELResolver.java:53)
        at com.sun.faces.el.FacesCompositeELResolver.getValue(FacesCompositeELResolver.java:64)
        at org.jboss.el.parser.AstPropertySuffix.getValue(AstPropertySuffix.java:53)
        at org.jboss.el.parser.AstValue.getValue(AstValue.java:67)
        at org.jboss.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:186)
        at com.sun.facelets.el.TagValueExpression.getValue(TagValueExpression.java:71)
        ... 47 more

[pmuir]

Please enclose the stack trace in back ticks (`stack trace`) and make sure to include the root cause.

And yes, it is relevant - I'm not in the habit of making random changes to Seam source on the advice of people from a public forum without understanding their issue first. And I happen to think this is a good thing.

And in this case, the bug is yours. You can't call methods like isNextExists() on a query where you haven't set the maxResults() (it doesn't make any sense if you think carefully).

But we could have a better error message explaining this. So please put an issue for the error message in JIRA.

[trentlarson]

A little more background may help: I started with a HSQL DB with 2 tables (Client and Partner), then ran seam-gen to set up my project and I have not manually changed any code.  I started Jboss and went to my app, then clicked on ClientView on the top and got the error.  So the origin of the problem may actually be in the seam-gen piece, such as the 'new-project' task.

Good luck.  I'll add a JIRA task now for the error message; let me know if you want another one for this new-project problem.

07:50:27,570 ERROR [STDERR] Mar 14, 2008 7:50:27 AM com.sun.facelets.FaceletViewHandler handleRenderException
SEVERE: Error Rendering View[/ClientList.xhtml]
javax.faces.FacesException: javax.el.ELException: /ClientList.xhtml @347,33 rendered="#{clientList.nextExists}": Error reading 'nextExists' on type com.icentris.moneplanner.admin.session.ClientList_$$_javassist_2
        at javax.faces.component.UIComponentBase.isRendered(UIComponentBase.java:373)
        at javax.faces.component.UIComponent.encodeAll(UIComponent.java:880)
        at javax.faces.component.UIComponent.encodeAll(UIComponent.java:892)
        at com.sun.facelets.FaceletViewHandler.renderView(FaceletViewHandler.java:592)
        at org.ajax4jsf.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:108)
        at org.ajax4jsf.application.AjaxViewHandler.renderView(AjaxViewHandler.java:216)
        at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:106)
        at com.sun.faces.lifecycle.LifecycleImpl.phase(LifecycleImpl.java:251)
        at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:144)
        at javax.faces.webapp.FacesServlet.service(FacesServlet.java:245)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
        at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:83)
        at org.jboss.seam.debug.hot.HotDeployFilter.doFilter(HotDeployFilter.java:68)
        at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
        at org.jboss.seam.web.MultipartFilter.doFilter(MultipartFilter.java:85)
        at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
        at org.jboss.seam.web.ExceptionFilter.doFilter(ExceptionFilter.java:64)
        at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
        at org.jboss.seam.web.RedirectFilter.doFilter(RedirectFilter.java:45)
        at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
        at org.ajax4jsf.webapp.BaseXMLFilter.doXmlFilter(BaseXMLFilter.java:141)
        at org.ajax4jsf.webapp.BaseFilter.doFilter(BaseFilter.java:281)
        at org.jboss.seam.web.Ajax4jsfFilter.doFilter(Ajax4jsfFilter.java:60)
        at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
        at org.jboss.seam.web.LoggingFilter.doFilter(LoggingFilter.java:58)
        at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
        at org.jboss.seam.servlet.SeamFilter.doFilter(SeamFilter.java:158)
        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.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:432)
        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:595)
Caused by: javax.el.ELException: /ClientList.xhtml @347,33 rendered="#{clientList.nextExists}": Error reading 'nextExists' on type com.icentris.moneplanner.admin.session.ClientList_$$_javassist_2
        at com.sun.facelets.el.TagValueExpression.getValue(TagValueExpression.java:76)
        at javax.faces.component.UIComponentBase.isRendered(UIComponentBase.java:370)
        ... 46 more
Caused by: java.lang.NullPointerException
        at org.jboss.seam.framework.EntityQuery.isNextExists(EntityQuery.java:47)
        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:585)
        at org.jboss.seam.util.Reflections.invoke(Reflections.java:21)
        at org.jboss.seam.intercept.RootInvocationContext.proceed(RootInvocationContext.java:31)
        at org.jboss.seam.intercept.SeamInvocationContext.proceed(SeamInvocationContext.java:56)
        at org.jboss.seam.transaction.RollbackInterceptor.aroundInvoke(RollbackInterceptor.java:31)
        at org.jboss.seam.intercept.SeamInvocationContext.proceed(SeamInvocationContext.java:68)
        at org.jboss.seam.transaction.TransactionInterceptor$1.work(TransactionInterceptor.java:38)
        at org.jboss.seam.util.Work.workInTransaction(Work.java:40)
        at org.jboss.seam.transaction.TransactionInterceptor.aroundInvoke(TransactionInterceptor.java:32)
        at org.jboss.seam.intercept.SeamInvocationContext.proceed(SeamInvocationContext.java:68)
        at org.jboss.seam.core.MethodContextInterceptor.aroundInvoke(MethodContextInterceptor.java:42)
        at org.jboss.seam.intercept.SeamInvocationContext.proceed(SeamInvocationContext.java:68)
        at org.jboss.seam.intercept.RootInterceptor.invoke(RootInterceptor.java:107)
        at org.jboss.seam.intercept.JavaBeanInterceptor.interceptInvocation(JavaBeanInterceptor.java:166)
        at org.jboss.seam.intercept.JavaBeanInterceptor.invoke(JavaBeanInterceptor.java:102)
        at com.icentris.moneplanner.admin.session.ClientList_$$_javassist_2.isNextExists(ClientList_$$_javassist_2.java)
        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:585)
        at javax.el.BeanELResolver.getValue(BeanELResolver.java:62)
        at javax.el.CompositeELResolver.getValue(CompositeELResolver.java:53)
        at com.sun.faces.el.FacesCompositeELResolver.getValue(FacesCompositeELResolver.java:64)
        at org.jboss.el.parser.AstPropertySuffix.getValue(AstPropertySuffix.java:53)
        at org.jboss.el.parser.AstValue.getValue(AstValue.java:67)
        at org.jboss.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:186)
        at com.sun.facelets.el.TagValueExpression.getValue(TagValueExpression.java:71)
        ... 47 more

[trentlarson]

<tail between my legs>

Well, nevermind: I just ran through the whole sequence again and this time it worked.  I'll keep my eyes open for this same thing, and I'll give the full story next time.

Thanks forcing me to continue!  And sorry for the distraction.

</tail...>

[trentlarson]

Aha!  I found the situation: in the generated ...List.java code, it implements the getMaxResults method; however, when this is implemented, Hibernate includes a top ? in my select statements for the FrontBase driver which breaks the driver.  Ug.  To work around this, I removed the getMaxResults implementation, and then Hibernate creates SQL that doesn't break when talking to the DB.  But it appears that causes other problems.

So I did change some code from the generated templates.  I now have to find a way to stop Hibernate from generating that code and still make sure other code doesn't break.

BTW, I must disagree that isNextExists should throw errors if there is no maxResults set; I expect my DAO layer should be able to show me everything even if that's not set.  The EntityQuery.createQuery method and the Query.getPageCount methods handle this situation, so I don't see why isNextExists should break.  At very least, let's document that dependency; I'll put that suggestion in the JIRA task.

(Oh, and BTW, kudos to the Seam for making it so easy to get up and running with an entire application.  That's sweet.)

Cheers!

[pmuir]

I think that a better exception would be the best thing.

[wiggy]

hit the same problem -

i fixed it by copying the EntityQuery into my own space and correcting the errors i saw - did this for next/last previous functions

see

http://www.seamframework.org/Community/SeamFrameworkEntityQueryBug

i just posted - this may help you get past the initial problem until a 'well designed' fix is put in place.

I have this working on my form now.  Didnt trawl through all the cases yest so probably more errors to come out .

[fernando_jmt]

JIRA issue added: http://jira.jboss.com/jira/browse/JBSEAM-2747