originalPayload not the same as message.originalPayload in groovy scripts - mule

Question

I found that originalPayload does not do the same as message.originalPayload in groovy expressions. That is, the following transformers do not do the same thing:
with originalPayload:
<expression-transformer evaluator="groovy" expression="originalPayload" />
with message.originalPayload:
<expression-transformer evaluator="groovy" expression="message.originalPayload" />
The following mule configuration and test case can be used to reproduce the issue:
<mule ...>
<flow name="test">
<vm:inbound-endpoint name="test.Name" path="test.Path"
exchange-pattern="request-response" />
<expression-transformer evaluator="string" expression="bar" />
<expression-transformer evaluator="groovy" expression="originalPayload" />
<!-- or alternatively -->
<!-- <expression-transformer evaluator="groovy" expression="message.originalPayload" /> -->
</flow>
</mule>
The test case can be:
#Test
public void transformers() throws MuleException {
final MuleClient client = muleContext.getClient();
final MuleMessage reply = client.send("vm://test.Path", 1, null, RECEIVE_TIMEOUT);
assertEquals(1, reply.getPayload());
}
The alternative with message.originalPayload works as expected. The one with originalPayload does not and the following exception is shown in the logs:
Exception stack is:
1. Expression Evaluator "groovy" with expression "originalPayload" returned null
but a value was required. (org.mule.api.expression.RequiredValue Exception)
What could I be doing wrong?
Thanks.

Answer 1

The problem is that expression-transformer and scripting:transformer use a different set of bindings than the one used by a scripting:component, and this because they call a different method in org.mule.module.scripting.component.Scriptable.
Moreover, when originalPayload gets bound, it is with the wrong value:
bindings.put("originalPayload", event.getMessage().getPayload());
Hence: MULE-6215

Answer 2

Following the Scripting Module Reference, they should be the same.
Also, if you take a look to org.mule.module.scripting.component.Scriptable in the scripting module, you will find that "originalPayload" is message.getPayload.
Can you post a small project reproducing the error?
public void populateBindings(Bindings bindings, MuleMessage message)
{
populateDefaultBindings(bindings);
if (message == null)
{
message = new DefaultMuleMessage(NullPayload.getInstance(), muleContext);
}
bindings.put("message", message);
//This will get overwritten if populateBindings(Bindings bindings, MuleEvent event) is called
//and not this method directly.
bindings.put("payload", message.getPayload());
//For backward compatability
bindings.put("src", message.getPayload());
}
public void populateBindings(Bindings bindings, MuleEvent event)
{
populateBindings(bindings, event.getMessage());
bindings.put("originalPayload", event.getMessage().getPayload());
bindings.put("payload", event.getMessage().getPayload());
bindings.put("eventContext", new DefaultMuleEventContext(event));
bindings.put("id", event.getId());
bindings.put("flowConstruct", event.getFlowConstruct());
if (event.getFlowConstruct() instanceof Service)
{
bindings.put("service", event.getFlowConstruct());
}
}