Azure Data Explorer: Multi-Select Parameter "Select All" return all possible options instead

Question

In Azure Data Explorer (dashboards, accessed via the web at the URL: dataexplorer.azure.com/dashboards/ ), a multi-select parameter will return empty (isempty() == true) if the "Select All" option is picked. However, I need to know all of the options if the "select all" option is picked. Is there a way to do this?

Here is an example of my Kusto query that the multiselect parameter feeds into. You will see that the "in" filter means I need a complete list of all of the options / values of the multiselect param.

Events
| where FilteredItem in (_multiselectParameter)
| where Timestamp between(_startTime.._endTime)
| summarize event_count = count() by bin(Timestamp, make_timespan(_timeSpan))

Thanks in advance for your help!

Answer 1

The way to write the Where clause, taking into consideration the "Select All" options is as follows:

| where FilteredItem in (_multiselectParameter) or isempty(_multiselectParameter)