Dashboard List Widget - Find Distinct $datapoints

[moremeowbell]

I am looking for some help regarding an Arcade script that I am developing for the ESRI Dashboard List Widget. Essentially, I have a hosted feature table that has duplicate records based on "unique_user" but must remain split due to some non-duplicate attributes. I would like to only display only one DISTINCT record, based on "unique_user." As long as the script only returns one $datapoint then that is fine - the index does not matter.

Here is what I have so far, any thoughts on how to only return one distinct value per "unique_user"?

// different categories of days anticipated
var perm_status = $datapoint["perm_status"]
var dateTechReviewComplete = Date($datapoint["dt_tech_review_complete"])

// extra variables
var dateSubmitted = Date($datapoint["dt_submitted"])
var nowDate = Date(Now())

if (perm_status == "Technical Review Complete") {
    var tech = DateAdd(dateTechReviewComplete, 195, 'days')
    var daysAnt = Text(tech, "MMMM D, Y")
    var dateDifference = Round(DateDiff(tech, nowDate, 'days'))
    // Return only one DISTINCT date based upon "unique_user"
}
else {
    var daysAnt = "No Permit Status Reported"
    return True
}

return {
  textColor: '',
  backgroundColor: '',
  separatorColor:'',
  selectionColor: '',
  selectionTextColor: '',
  attributes: {
    daysAnticipated: daysAnt,
    permitStatus: perm_status,
    daysDifference: dateDifference
  }
}

This is what the code currently returns, duplicates have a red mark next to them:

The desired result is that only one of the duplicate rows is returned.

[jcarlson]

To get distinct values, you need to either:

1. Write a Data Expression that filters them out, or
2. Use a Table widget, which has built-in grouping

In the Advanced Formatting part of the widget, your Arcade expression can only evaluate per-row, and it can't "see" other features in the layer.

[moremeowbell]

Thanks! Do you know how I would write a data expression to filter?

[jcarlson]

You can find a bunch of examples here:

https://github.com/Esri/arcade-expressions/tree/master/dashboard_data

Your particular case is easy enough, since the requirement is to remove duplicates. There is an Arcade function Distinct, which returns a FeatureSet.

Try this:

var fs = FeatureSetByPortalItem(
  Portal('your portal url'),
  'itemid of the service',
  0,
  ['fields', 'you', 'want'],
  false
)

return Distinct(
  fs,
  ['fields', 'you', 'want']
)

[moremeowbell]

Thanks for the link, really helpful! 

When attempting to return Distinct values, I am getting this Console error. We only have Enterprise 10.9.1 - do you think that may be a reason the analysis isn't supported?

[jcarlson]

What you're seeing is a result of  the particular Profile you're using.

https://developers.arcgis.com/arcade/profiles/

In the Advanced Formatting, you cannot use FeatureSet functions. To use a Data Expression, you've actually got to go all the way back to where you choose a data layer for the widget, then say "New Data Expression" there.