Creating Data Expressions

JD1016

Hello,

I'm new to Arcade and even newer to creating Data Expressions in Dashboards.  I have three fields that I can populate using Arcade in my AGO web map Configure Pop-Ups section.  Unfortunately, as we all know, these type of calculated fields do not show up in Dashboards and Globals are not present.  I've been reading over past postings and it seems the key for me would be to employ FeatureSetByPortalItem() and create a data expression inside Dashboards so this data can be used.  The three fields are Temporal Block, Hour, and Weekday. 

The code I'm using in AGO for Temporal Block is:

var t = Hour($feature.PresentDate);

When(

  t >= 22 || t < 6, "Night (10pm - 6am)",

  t >= 6 && t < 11, "Morning (6am - 11am)",

  t >= 11 && t < 13, "Midday (11am - 1pm)",

  t >= 13 && t < 17, "Afternoon (1pm - 5pm)",

  t >= 17 && t < 22, "Evening (5pm - 10pm)",

"Invalid date" );

The code I'm using in AGO for Hour is:

Hour($feature.PresentDate)

And the code I am using in AGO for Weekday is:

Weekday($feature.PresentDate)

Can someone please help me or give me some hints at how to create an Arcade expression employing FeatureSetByPortalItem that will perform these calculations inside Dashboard?

Thank you so much in advance.

Jeff

jcarlson

You'll want to check out the Arcade GitHub repo for lots of examples.

If all you want is to get those three items into your Data Expression, that's easy enough. The basic things to know about data expressions are the FeatureSetByPortalItem function to get your inputs, and then the basic structure of a FeatureSet's JSON definition so that you can build your own.

Also, just a side note: when you've got multiple conditions, they evaluate in order. So anything that fails to meet the ">= 22" condition will be less than 22 (or null) by definition, so you don't need to later use "< 22". Especially when you're using a numeric value, you can just evaluate in ascending or descending order.

And a side side note: since you're working with the hours field and one of your decoded strings spans the midnight mark, you can get that into a single condition by using the modulo (%) operator. Put another way, 23 % 22 = 1. So in the initial condition in that when function, we can use that to reduce the >= 22 hours to a small number that will be caught in the same condition.

var portal = Portal('your portal url')

var fs = FeatureSetByPortalItem(
    portal,
    'itemID of your service',
    0, // or whatever the layer index is
    ['PresentDate', 'any', 'other', 'fields', 'you', 'want'],
    false // unless you really need geometry, but it performs much better without
)

// Create a dictionary to hold our output
var out_dict = {
    fields: [
        {name: 'PresentDate', type: 'esriFieldTypeDate'},
        {name: 'Weekday',     type: 'esriFieldTypeString'},
        {name: 'Hour',        type: 'esriFieldTypeInteger'},
        {name: 'TimeString',  type: 'esriFieldTypeString'}
        // include any other fields you want in the output here
    ],
    geometryType: '',
    features: []
}

// Iterate over features, calculate new fields, push to dictionary
for (var f in fs){
    var t = Hour(f['PresentDate'])
    
    var time_str = When(
        (t % 22) < 6, "Night (10pm - 6am)",
        t < 11, "Morning (6am - 11am)",
        t < 13, "Midday (11am - 1pm)",
        t < 17, "Afternoon (1pm - 5pm)",
        t < 22, "Evening (5pm - 10pm)",
        t < 24, "Night (10pm - 6am)",
        "Invalid date"
    )
    
    var wkday = Weekday(f['PresentDate'])
    
    Push(
        out_dict['features'],
        {
            attributes: {
                PresentDate: f['PresentDate'],
                Weekday: wkday,
                Hour: t,
                TimeString: time_str
            }
        }
    )
}

return FeatureSet(Text(out_dict))

 

It looks like a lot, but once you get the basic syntax down, it's not that bad.