Unavailable Scope Variable causes SpelEvaluationException: EL1008E

[BADJAN]

Hi all,

currently I'm migrating from Spring 2.x, Spring Security 2.0.4 and Spring Webflow 2.0.8 to Spring 3.0.5, Spring Security 3.0.5 and Webflow 2.2.1.

I'm facing following Exception when a scoped variable is not set, but given in the flowdefinition.

Caused by: org.springframework.expression.spel.SpelEvaluationException: EL1008E:(pos 16): Field or property 'newDocumentation' cannot be found on object of type 'org.springframework.webflow.engine.impl.RequestControlContextImpl'
	at org.springframework.expression.spel.ast.PropertyOrFieldReference.readProperty(PropertyOrFieldReference.java:207)
	at org.springframework.expression.spel.ast.PropertyOrFieldReference.getValueInternal(PropertyOrFieldReference.java:71)
	at org.springframework.expression.spel.ast.MethodReference.getValueInternal(MethodReference.java:64)
	at org.springframework.expression.spel.ast.CompoundExpression.getValueInternal(CompoundExpression.java:57)
	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:78)
	... 88 more

In Webflow 2.0.8 a variable, which is not in scope returns NULL, now in 2.2.1 this Exception is thrown - that breaks my whole application

To be more specific - here are the settings:

flowdefinition: documentation.xml

<view-state id="enterDocumentation">
	<transition on="edit" to="editDocumentation">
		<evaluate expression="DocumentationBB.init(SoDocumentationEDM.rowData)" result="flowScope.selectedDocumentation"/>
	</transition>
	<transition on="create" to="editDocumentation">
		<evaluate expression="DocumentationBB.init(newDocumentation)" result="flowScope.selectedDocumentation"/>
	</transition>
</view-state>
<view-state id="editDocumentation">
...
</view-state>

java code: DocumentationBB.java

public SoDocumentation init(SoDocumentation doc){
	if(doc == null){
		doc = new SoDocumentation();
		...
	}
		
	return doc;
}

This flowdefinition throws the SpelEvaluationException when transition 'create' should be executed (using WebFlow 2.2.1 and Spring/Security 3.0.5). With WebFlow 2.0.8 and Spring/Security 2.x - this worked without any errors.

To get this flow working in 2.2.1 I have to change the flowdefinition as follows:

<transition on="create" to="editDocumentation">
    <evaluate expression="DocumentationBB.init(flowScope.newDocumentation)" result="flowScope.selectedDocumentation"/>
</transition>

So can someone please tell me if I did something wrong or if this behaviour is a bug or a new feature?
If this is a new feature, is it possible to tweak some settings to use the old behaviour? ...otherwise I have to rewrite all our flows.

Thanks in advance - Jan

[BADJAN]

I think this behaviour is based on a change in the flow search algorithm...

Looking at org.springframework.webflow.expression.spel.ScopeS earchingPropertyAccessor
which is called by org.springframework.expression.spel.ast.PropertyOr FieldReference
by method:

private TypedValue readProperty(ExpressionState state, String name) throws EvaluationException

ScopeSearchingPropertyAccessor

public boolean canRead(EvaluationContext context, Object target, String name) throws AccessException {
		return (findScopeForAttribute((RequestContext) target, name) != null);
	}

private MutableAttributeMap findScopeForAttribute(RequestContext requestContext, String name) {
		if (requestContext.getRequestScope().contains(name)) {
			return requestContext.getRequestScope();
		}
		if (requestContext.getFlashScope().contains(name)) {
			return requestContext.getFlashScope();
		}
		if (requestContext.inViewState() && requestContext.getViewScope().contains(name)) {
			return requestContext.getViewScope();
		}
		if (requestContext.getFlowScope().contains(name)) {
			return requestContext.getFlowScope();
		}
		if (requestContext.getConversationScope().contains(name)) {
			return requestContext.getConversationScope();
		}
		return null;
	}

Of course this will return null/false, cause without a doubt my variable 'newDocumentation' doesnt exists in any scope. With respect to the PropertyAccessor based implementation, it wouldn't make sense if a the ScopeSearchingPropertyAccessor would fake it could handle this variable and just return a null value at the end. ...there would be still the chance any other Accessor could handle my variable...

So i think the next question is: Is it somehow possible to use something this way:

<transition on="create" to="editDocumentation">
			<evaluate expression="DocumentationBB.init(NULL)" result="flowScope.selectedDocumentation"/>
		</transition>

create/use NULL variables just within the flow??

[boudewijn]

Hello,

did you find any solution/workaround for this?

regards, Bo