Mule ESB groovy evaluator key cannot be empty exception

Question

I am having problems with a groovy evaluator in mule that gets an invocation property from the message and chekcs if it is null. The code is:

<when expression="#[groovy: (message.getInvocationProperty('firstName', null) != null)]">

This throws"

 1.key can not be empty (java.lang.IllegalArgumentException)
  javax.script.SimpleBindings:-1 (null)
 2. key can not be empty (java.lang.IllegalArgumentException). Message payload is of type:         String (org.mule.api.MessagingException)

org.mule.execution.ExceptionToMessagingExceptionExecutionInterceptor:32 ( http://www.mulesoft.org/docs/site/current3/apidocs/org/mule/api/MessagingException.html )

At this point i know that firstName property is indeed null - it is not set in the message, but shouldn`t getInvocationProperty('firstName', null) set the property to null as a default value if it is not set?

Any ideas how to solve this?

Thanks

Answer 1

Try using this choice:

<flow name="loan-broker">
    <http:inbound-endpoint host="127.0.0.1" port="8080" path="in" exchange-pattern="request-response"/>
    <set-variable variableName="prop" value="value" />
    <choice>
        <when expression="#[flowVars['prop'] != null]" >
            <set-payload value="#['prop: ' + flowVars['prop']]"/>
        </when>
        <otherwise>
            <set-payload value="Houston, we have a problem."/>
        </otherwise>
    </choice>
</flow>

Call it using:

curl http://127.0.0.1:8080/in

You should get value

Answer 2

I finally managed to solve this problem by upgrading mule and using MEL. So the expression now looks like this.

<when expression="#[flowVars.firstName != empty]">

'flowVars' stores all invocation properties and variables assigned in the flow, and if the flow has been called through the

<flow-ref />

all the variables set in the caller flow will be available through the 'flowVars'.

Answer 3

I had same issue, solved with following expression:

<set-variable variableName="firstName" value="${fname}" doc:name="Variable"/>
<when expression="#[flowVars.firstName.isEmpty()]">
     <logger message="===== If ===" level="INFO" doc:name="Logger"/>    
</when>
<otherwise>
     <logger message="===== Else ===" level=" INFO" doc:name="Logger"/> 
</otherwise>