ScopeSearchingPropertyAccessor cause NPE [SWF-1572]

[spring-operator]

Felix Martin opened SWF-1572 and commented

ScopeSearchingPropertyAccessor causes a NPE if it's elected to access a property the first time the expression is evaluated and can't recover the property the following times.

Attached there is a project to reproduce the error:

• If we start the application and the first request is /webflow-tests/scopeSearchingProps?test=kk, subsequents requests to /webflow-test/scopeSearchinProps throw a NPE
• If we start the application and the first request is /webflow-tests/scopeSearchingProps, subsequents requests to /webflow-test/scopeSearchinProps work fine

---

Affects: 2.1.1, 2.3.0

Reference URL: http://www.linkedin.com/groups/Anyone-having-expertise-in-Spring-46964.S.169940852?qid=40c39805-87f8-4d0d-a256-85d82ab5f71f&trk=group_most_popular-0-b-ttl&goback=.gmp_46964.gde_46964_member_169940852.gmp_46964

Attachments:

• webflow-tests.zip (13.23 kB)

[spring-operator]

Felix Martin commented

I think the method read should throw an AccessException if scope == null

[spring-operator]

Phil Webb commented

java.lang.NullPointerException
	at org.springframework.expression.spel.ast.PropertyOrFieldReference.getValueInternal(PropertyOrFieldReference.java:75)
	at org.springframework.expression.spel.ast.CompoundExpression.getValueInternal(CompoundExpression.java:52)
	at org.springframework.expression.spel.ast.SpelNodeImpl.getTypedValue(SpelNodeImpl.java:102)
	at org.springframework.expression.spel.standard.SpelExpression.getValue(SpelExpression.java:97)
	at org.springframework.binding.expression.spel.SpringELExpression.getValue(SpringELExpression.java:84)
	at org.springframework.webflow.action.EvaluateAction.doExecute(EvaluateAction.java:75)
	at org.springframework.webflow.action.AbstractAction.execute(AbstractAction.java:188)
	at org.springframework.webflow.execution.AnnotatedAction.execute(AnnotatedAction.java:145)
	at org.springframework.webflow.execution.ActionExecutor.execute(ActionExecutor.java:51)
	at org.springframework.webflow.engine.ActionState.doEnter(ActionState.java:101)
	at org.springframework.webflow.engine.State.enter(State.java:194)
	at org.springframework.webflow.engine.Transition.execute(Transition.java:228)
	at org.springframework.webflow.engine.DecisionState.doEnter(DecisionState.java:51)
	at org.springframework.webflow.engine.State.enter(State.java:194)
	at org.springframework.webflow.engine.Flow.start(Flow.java:527)
	at org.springframework.webflow.engine.impl.FlowExecutionImpl.start(FlowExecutionImpl.java:368)
	at org.springframework.webflow.engine.impl.FlowExecutionImpl.start(FlowExecutionImpl.java:223)
	at org.springframework.webflow.executor.FlowExecutorImpl.launchExecution(FlowExecutorImpl.java:140)
	at org.springframework.webflow.mvc.servlet.FlowHandlerAdapter.handle(FlowHandlerAdapter.java:226)
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:923)
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:852)
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882)
	at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:778)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:304)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:224)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:185)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:151)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
	at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:929)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:405)
	at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:269)
	at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:515)
	at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:302)
	at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
	at java.lang.Thread.run(Thread.java:680)

[spring-operator]

Phil Webb commented

commit 55a69b568fae03e9c59a858c0b0845bb1c609b93
Author: Phillip Webb <pwebb@vmware.com>
Commit: Phillip Webb <pwebb@vmware.com>

    Fix potential ScopeSearchingPropertyAccessor NPE
    
    ScopeSearchingPropertyAccessor.read() now returns a TypedValue
    representing null rather than null itself.  This prevents a
    NullPointerException from being thrown from deeper within the Spring
    SpEL code
    
    Issue: SWF-1572

[spring-operator]

Phil Webb commented

Hi Felix,

Thanks for raising this, it should now be fixed in the latest 2.4 SNAPSHOT.

Cheers,
Phil.