Optional dropdown Parameter in Azure workbook

Question

I want to create an optional dropdown parameter in an Azure Workbook. Creating a dropdown parameter with this guide is straight forward

Then the parameter can be referenced in KQL as shown in the example with

 requests
    | where name == '{RequestName}'

So far so good, I now want this parameter to be optional and if a value is not selected in the dropdown to get all the results unfiltered, like I would get if the |where part was not there at all. Right now if this parameter is not set then I get a Query could not be parsed error.

Is this possible?

Answer 1

requests
| where isempty('{RequestName}') or (name == '{RequestName}')