Why doesn't an arcade expression work on a mapImageLayer

[JackFairfield]

When I apply an arcade expression to the value expression property of my unique value renderer, it doesn't seem to work as expected.

Here is a jsbin example using a modifyed sample that esri provides:

JS Bin - Collaborative JavaScript Debugging 

Here is the line in question:

valueExpression: "When($feature.type == 'Gravel', 'test')",

I would expect this to filter the layer down and only show 7 features, just like when the filter is applied in the rest endpoint. 

But instead, all of the features in the map adopt the uvr symbol:

[MunachisoOgbuchiekwe · Accepted solution]

Hello Jack, 

As per documentation, Arcade expressions are not supported with MapImageLayers. Only FeatureLayers and SceneLayers are supported.

[JackFairfield]

Thank you for your reply.  Do you know if this feature will be supported in a future release?  If so, when?

[JackFairfield]

And are there any possible workarounds to make something similar to this work?

[MunachisoOgbuchiekwe]

Hello Jack, 

If I am understanding what you are trying to do, you could do the following....

1. Do a queryTask on the Map Service. This will return a Feature Set. 
2. You can use the Feature Set as the source for a Feature Layer object.
3. Then apply a unique value renderer to that Feature Layer and add it to the map. 

This would display only what you queried, as a custom Feature Layer. Below is sample code I came up with. Let me know if this is a misunderstanding of your question.

require([
        "esri/Map",
        "esri/views/MapView",
        "esri/layers/MapImageLayer",
        "esri/tasks/support/Query",
        "esri/tasks/QueryTask",
        "esri/layers/FeatureLayer",
        "dojo/domReady!"
    ],
    function (Map, MapView, MapImageLayer, Query, QueryTask, FeatureLayer) {


        //Create a new map and set the basemap to Dark gray
        var map = new Map({
            basemap: "dark-gray",
            //layers: [featureLayer]
        });

        //set a new view and set the properties of the view
        var view = new MapView({
            container: "viewDiv",
            map: map,
            center: [-86.049, 38.485],
            zoom: 3
        });

        var queryStatesTask = new QueryTask({
            url: "https://sampleserver6.arcgisonline.com/arcgis/rest/services/USA/MapServer/2"
        });

        var quakesRenderer = {
            type: "simple", // autocasts as new SimpleRenderer()
            symbol: {
                type: "simple-fill", // autocasts as new SimpleMarkerSymbol()
                //style: "circle",
                size: 20,
                color: [211, 255, 0, 0],
                outline: {
                    width: 1,
                    color: "#FF0055",
                    style: "solid"
                }
            }
        }

        var query = new Query();
        query.where = "state_name = 'California'";
        query.returnGeometry = true;
        queryStatesTask.execute(query).then(function (result) {
            //console.log(result);
            var fl = new FeatureLayer({
                source: result.features, // autocast as an array of esri/Graphic
                // create an instance of esri/layers/support/Field for each field object
                fields: result.fields, // This is required when creating a layer from Graphics
                objectIdField: "ObjectID", // This must be defined when creating a layer from Graphics
                renderer: quakesRenderer, // set the visualization on the layer
                spatialReference: result.spatialReference,
                geometryType: result.geometryType // Must be set when creating a layer from Graphics
            });
            map.add(fl);
        });
    });‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍