Arcade in dashboard challenges

Question

Hello,

I have a polygon layer (my city's districts) and a point layer (new trees planted in my city). The tree points are crowd-sourced from a survey 123, it is therefore a shared update layer with sync enabled.

I want to display how many tree points are planted per district in a dashboard, perhaps in a list. For instance:
District A: 35 new trees
District B: 2 new trees

How can I connect the district polygon layer and the tree point layer in dashboard?

Here is what I have attempted so far:

In map viewer I have successfully done this using arcade in popup for the district polygon layer:

var treepoints= FeatureSetByName($map, "new_tree_points")
var numberoftrees= Count(Contains(treepoints,$feature))
return numberoftrees

This expression does not function in dashboard because I cannot figure out how to refer to another layer than the one I have selected. I have understood that the arcade profiles are different for map viewer and dashboard. In both dashboard List settings and Data expressions I have tried FeatureSetByPortalItem, but I get error message "Parse Error:featuresetbyportalitem is not available". My AGOL organization has not yet implemented Portal, is this the reason I cannot refer to a portal item?

I have also tried to calculate a field with this value and just show the new field in the dashboard list, but I have the same challenge with figuring out how to refer to another layer/feature. I also understand that Arcade cannot be used on hosted features with sync enabled so this may not be the way to go. Any pointers are appreciated.

Thanks in advance.

jcarlson · Answer

It really depends on where in the Dashboard you're using Arcade, and what exactly you're trying to do with it. If all you want is a list with a count in it, that's not terribly difficult, but accessing other layers in a Dashboard Arcade profile does require a bit more work than usual.

This example should give you a good idea:

// Portal
var portal = Portal('https://www.arcgis.com/');

// Create FeatureSet for polygons
var poly_fs = FeatureSetByPortalItem(
    portal,
    '312cebfea2624e108e234220b04460b8',
    0,
    [
        'ZONE'
    ],
    true
);

// Create Featureset for points
var pt_fs = FeatureSetByPortalItem(
    portal,
    '848d61af726f40d890219042253bedd7',
    0,
    [
        'capacity_mw'
    ],
    true
);

// Create empty feature array for output
var features = [];

// Iterate over time zones
for (var poly in poly_fs) {

// Filter points by polygon
    var pts = Contains(poly, pt_fs);

// Create feature with aggregated values
    var feat = { 
        'attributes': { 
            'tz': poly['ZONE'], 
            'pt_cnt': Count(pts)
        }
    };

// Push feature into array
    Push(features, feat);
};

// Create dict for output FeatureSet
var out_dict = { 
    'fields': [
        {'name': 'tz', 'alias': 'Time Zone', 'type': 'esriFieldTypeFloat'},
        {'name': 'pt_cnt', 'alias': 'Number of Power Plants', 'type': 'esriFieldTypeInteger'}
    ],
  'geometryType': '', 
  'features': features 
};

// Convert dictionary to feature set. 
return FeatureSet(Text(out_dict));

And the output:

DominicRobergeIADOT · Answer

Try this

var treepoints= FeatureSetByName($map, "new_tree_points")
var numberoftrees= Count(Contains($feature,treepoints))
return numberoftrees