How does decision state investigate nested properties?

[Colin Yates]

Hi, I have an interface called Page {
Collection<Page> getPages();
}

I have a decision state with the following expression: ${requestScope.page.pages == null}

and I get the following stack trace:

14:15:05,484 ERROR [Engine] StandardWrapperValve[sitebuilder]:Servlet.service() for servlet sitebuilder threw exception org.springframework.beans.NotReadablePropertyException: Invalid property 'requestScope.page' of bean class [org.springframework.web.flow.execution.impl.StateContextImpl]: Bean property 'requestScope.page' is not readable or has an invalid getter  method: Does the return type of the getter match the parameter type of the setter?
        at org.springframework.beans.BeanWrapperImpl.getPropertyValue(BeanWrapperImpl.java:634)
        at org.springframework.beans.BeanWrapperImpl.getNestedBeanWrapper(BeanWrapperImpl.java:535)
        at org.springframework.beans.BeanWrapperImpl.getBeanWrapperForPropertyPath(BeanWrapperImpl.java:513)
        at org.springframework.beans.BeanWrapperImpl.getBeanWrapperForPropertyPath(BeanWrapperImpl.java:514)
        at org.springframework.beans.BeanWrapperImpl.getPropertyValue(BeanWrapperImpl.java:624)
        at org.springframework.binding.expression.support.BeanWrapperEvaluator.evaluate(BeanWrapperEvaluator.java:25)
        at org.springframework.web.flow.config.TextToTransitionCriteria$ExpressionTransitionCriteria.test(TextToTransitionCriteria
.java:133)
        at org.springframework.web.flow.Transition.matches(Transition.java:228)
        at org.springframework.web.flow.TransitionableState.getTransition(TransitionableState.java:166)
        at org.springframework.web.flow.TransitionableState.getRequiredTransition(TransitionableState.java:179)
        at org.springframework.web.flow.DecisionState.doEnter(DecisionState.java:110)

Not sure what the problem is?

Any ideas?

Any *yes* there is an object called Page of type Page in requestScope

[Colin Yates]

OK, so it is the same problem as http://forum.springframework.org/showthread.php?t=15263

Is there no way the framework can throw a ClassNotFound exception if it cannot find OGML?

[Keith Donald]

Well right now we try OGNL and if not there we use Spring's bean wrapper. I don't think we want to mandate OGNL, though perhaps its better to rely on an explicit set of a default rather than a fallback. Not sure.

In any case we've improved logging for PR4 with this -- it'll info you if ognl is not in the classpath.

[Colin Yates]

Cool.