<evaluate expression="" result="" />

[joshjdevl]

Actually, I need more help with these...is there a link to some technical details how this work?

I need to set some sort of error message if there is an exception and I'm transitioning

		<transition on-exception="java.lang.Exception" to="register">
			<set name="flashScope.register.alreadyRegisteredErrorMsg" value="'You have already registered'"/>
		</transition>

When I add the set name I get a stack overflow error

java.lang.StackOverflowError
	at java.lang.StringBuilder.append(StringBuilder.java:119)
	at java.lang.Object.toString(Object.java:219)

...

	at org.springframework.core.style.DefaultValueStyler.style(DefaultValueStyler.java:72)
	at org.springframework.core.style.DefaultToStringStyler.styleValue(DefaultToStringStyler.java:91)
	at org.springframework.core.style.DefaultToStringStyler.styleField(DefaultToStringStyler.java:79)
	at org.springframework.core.style.ToStringCreator.append(ToStringCreator.java:156)
	at org.springframework.webflow.engine.impl.FlowExecutionImpl.toString(FlowExecutionImpl.java:520)
	at java.lang.String.valueOf(String.java:2827)
	at org.springframework.core.style.DefaultValueStyler.style(DefaultValueStyler.java:78)
	at org.springframework.core.style.DefaultToStringStyler.styleValue(DefaultToStringStyler.java:91)
	at org.springframework.core.style.DefaultToStringStyler.styleField(DefaultToStringStyler.java:79)
	at org.springframework.core.style.ToStringCreator.append(ToStringCreator.java:156)
	at org.springframework.webflow.engine.impl.RequestControlContextImpl.toString(RequestControlContextImpl.java:232)
	at java.lang.String.valueOf(String.java:2827)
	at org.springframework.core.style.DefaultValueStyler.style(DefaultValueStyler.java:78)
	at org.springframework.core.style.DefaultToStringStyler.styleValue(DefaultToStringStyler.java:91)
	at org.springframework.core.style.DefaultToStringStyler.styleField(DefaultToStringStyler.java:79)
	at org.springframework.core.style.ToStringCreator.append(ToStringCreator.java:156)
	at org.springframework.binding.expression.EvaluationAttempt.createToString(EvaluationAttempt.java:62)
	at org.springframework.binding.expression.SetValueAttempt.createToString(SetValueAttempt.java:51)
	at org.springframework.binding.expression.EvaluationAttempt.toString(EvaluationAttempt.java:58)
	at java.lang.String.valueOf(String.java:2827)
	at java.lang.StringBuffer.append(StringBuffer.java:219)
	at org.springframework.binding.expression.EvaluationException.defaultMessage(EvaluationException.java:58)
	at org.springframework.binding.expression.EvaluationException.(EvaluationException.java:36)
	at org.springframework.binding.expression.ognl.OgnlExpression.setValue(OgnlExpression.java:102)
	at org.springframework.webflow.action.SetAction.doExecute(SetAction.java:76)
	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.ActionList.execute(ActionList.java:155)
	at org.springframework.webflow.engine.support.TransitionExecutingFlowExecutionExceptionHandler.handle(TransitionExecutingFlowExecutionExceptionHandler.java:109)
	at org.springframework.webflow.engine.FlowExecutionExceptionHandlerSet.handleException(FlowExecutionExceptionHandlerSet.java:113)
	at org.springframework.webflow.engine.State.handleException(State.java:222)
	at org.springframework.webflow.engine.impl.FlowExecutionImpl.tryStateHandlers(FlowExecutionImpl.java:615)
	at org.springframework.webflow.engine.impl.FlowExecutionImpl.handleException(FlowExecutionImpl.java:585)
	at org.springframework.webflow.engine.impl.FlowExecutionImpl.handleException(FlowExecutionImpl.java:590)
	at org.springframework.webflow.engine.impl.FlowExecutionImpl.handleException(FlowExecutionImpl.java:590)
	at org.springframework.webflow.engine.impl.FlowExecutionImpl.handleException(FlowExecutionImpl.java:590)
	at org.springframework.webflow.engine.impl.FlowExecutionImpl.handleException(FlowExecutionImpl.java:590)
	at org.springframework.webflow.engine.impl.FlowExecutionImpl.handleException(FlowExecutionImpl.java:590)
	at org.springframework.webflow.engine.impl.FlowExecutionImpl.handleException(FlowExecutionImpl.java:590)

Why? How do I properly use this?

[iwtolall]

I think if you would read the SWF 1.x documentation you will find something about it. I have quickly searched the SWF 2.x docu and only found it in the 1.0 to 2.0 Mappings section.
I have started with SWF 2.x and never had the motivation to read the 1.x documentation.
I'm sure the Webflow Team knows that the documentation is something which can be improved and if they find the time....

- Peter