Mule MEL validation

Question

My property file values are:

companies = test
companies1 =
companies2 = 'another'

now if I have a MEL validation like below doesn't work.

<choice  doc:name = "PageNum-1">
    <when expression = "#[ ${companies} != '' ]">
        <logger message = "===== Nothing to execute in process 1 ===" level="INFO" doc:name = "Logger"/>    
    </when>
    <otherwise>
        <logger message = "===== Nothing to execute in process 0 ===" level="INFO" doc:name = "Logger"/>    
    </otherwise>
</choice>

Error:

Exception stack is:
1. [Error: illegal use of operator: !=]
[Near : {... !='' ....}]
             ^
[Line: 1, Column: 1] (org.mule.mvel2.CompileException)

EDIT:

As a workaround solution, I have added a flow variable and verifying the data in expression as

<set-variable variableName = "company1" value = "${companies1}" doc:name = "company1"/>
<when expression = "#[flowVars.company1.isEmpty()]">

But, is there any simpler way to do with only by using $ as ${commpany1}

Víctor Romero Víctor Romero · Accepted Answer · 2015-01-31T01:13:43

Your problem is related with how the properties are replaced. They are replaced in a one-by-one fashion, so if you dont surround with quoes the property value companies, just like you did in companies2 it won't work.

Also, there is no need to use #[] when inside an expression attribute. The following did work for me:

<context:property-placeholder location="myprop.properties" />

<flow name="test-http">
    <http:inbound-endpoint host="127.0.0.1" port="8081"
        doc:name="HTTP" />
    <choice doc:name="PageNum-1">
        <when expression="${companies}!=''">
            <logger message="===== Nothing to execute in process 1 ==="
                level="INFO" doc:name="Logger" />
        </when>
        <otherwise>
            <logger message="===== Nothing to execute in process 0 ==="
                level="INFO" doc:name="Logger" />
        </otherwise>
    </choice>
</flow>

Mule MEL validation

3 Answers