How do I create a variable and set it equal to the count of a specific customEvent?

I have telemetry in my code that creates two custom events(longNameHere_event_success/longNameHere_event_error). I have a small AI Analytics query that looks for my events, gets the count of each, and renders a pie chart for a percentage metric.

As my event names are rather long, I'd like to create a variable for each to make the pie chart more legible.

customEvents
| where name contains "event"
|summarize count() by name
| render piechart

Current result is a pie chart with percentages for "longNameHere_event_success" and "longNameHere_event_error"

Desired result would be renaming "longNameHere_event_success" to "Success" and "longNameHere_event_error" to "Failure".

You can rename the column value as follows (I used an inline function for readability, but you can replace the function call with the case statement). Is this what you were looking for?

let rename = (original:string)
{
    case(original == "longNameHere_event_success", "success", 
         original == "longNameHere_event_error", "error", 
         "unknown")
};
let customEvents = datatable(name:string)
[
    "longNameHere_event_success",
    "longNameHere_event_success",
    "longNameHere_event_error"
];
customEvents
| where name contains "event"
| summarize count() by name
| project name  = rename(name), count_
| render piechart