Dashboard List Advanced Formatting null $datapoint values?

Question

I have a map layer that I am using to create a list of features in an ArcGIS Online dashboard. The list is set up to display some basic data from each feature, but I want to use Arcade to add an extra line that shows when the feature was last updated.

The last update timestamp is stored as a string in each feature ('YYYYMMDDHHMMSS') in a field called "LastGPSUpdate". I've written an Arcade Expression that works when I manually plug in a string, but whenever I try to reference the actual data, it returns null values. In fact, all of the "$datapoint.XYZ" globals return null values.

Any assistance would be much appreciated!

var dateInitial = $datapoint.LastGPSUpdate

var yearParse = Left(dateInitial, 4)
var monthParse = Right(Left(dateInitial, 6), 2)
var dayParse = Right(Left(dateInitial, 8), 2)

var dateParse = monthParse + '/' + dayParse + '/' + yearParse

Console(dateParse, $datapoint.BattalionArea,$datapoint.Beat,$datapoint.DispatchGroup,$datapoint.LastGPSUpdate,$datapoint.StationArea,$datapoint.Team,$datapoint.UnitType)

return {
  textColor: '',
  backgroundColor: '',
  separatorColor:'',
  selectionColor: '',
  selectionTextColor: '',
  dateText: dateParse
}

jamesw · Answer

Whoops, that was a typo in my example, thanks for catching that.

Unfortunately, changing to call it as {expression/dateParse} did not work. It is still returning null values in the console and no data is displayed in the list.

JA7 · Answer

return {
  textColor: '',
  backgroundColor: '',
  separatorColor:'',
  selectionColor: '',
  selectionTextColor: '',
  dateText: dateParse
}

Are you calling it as {expression/dateText}? In your response you are using {expression/dateParse} but that is not correct going by the return statement you had above. To make things simple, I always name the attributes the same name as my variable:

dateParse: dateParse

jamesw · Answer

Thanks for the tip about the Mid function, I haven't seen that one before.

It might just be my lack of understanding of Arcade in general, but I can't get any attribute to return a non-null value in the expression. I know that the data exists -- I can display it in the Line item template just fine, but for whatever reason, everything returns a null value when I try to use it in an expression.