topic Re: How to list all polygons in the feature layer? in ArcGIS JavaScript Maps SDK Questions

How to list all polygons in the feature layer?

Valgenmap — Thu, 07 Feb 2019 05:16:06 GMT

arcgis‌

I have added FeatureLayer as below into the map,

var map = new Map("map", {
basemap: "streets-navigation-vector",
showLabels:false,
showAttribution: false,
slider: false,
center: [-122.45, 37.75],
zoom: 10,
minZoom: 2,
});

var selectedBoundaryServiceUrl = "https://sampleserver1.arcgisonline.com/ArcGIS/rest/services/Demographics/ESRI_Census_USA/MapServer/3";

var stateLayer = new esri.layers.FeatureLayer(selectedBoundaryServiceUrl, {
id: "Selected_Layer",
opacity: 0.7,
mode: esri.layers.FeatureLayer.MODE_AUTO,
outFields: ["*"],
infoTemplate: infoTemplate
});

g_esri.map.addLayer(stateLayer);

I tried below line of code to get array of graphics in the layer.

var listOfGraphics = map.getLayer("Selected_Layer").graphics

But the output I'm getting as "Zero"

Here I'm adding the console output for reference.

Re: How to list all polygons in the feature layer?

KenBuja — Sat, 11 Dec 2021 14:34:28 GMT

You have to wait until the map is loaded before attempting to access its graphics. If you use "map.addLayer", then you'll have to use syntax to check when the specific layer is loaded (since the event fires each time a layer is loaded, including basemap layers)

    map.addLayer(featureLayer);
    map.on('layer-add-result', function(addLayer){
      if (addLayer.layer === featureLayer){
        console.log(featureLayer.graphics);
      }
    });‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Or you could use "map.addLayers", which fires when all layers are loaded.

    map.addLayers([featureLayer]);
    map.on('layers-add-result', function (){
      console.log(featureLayer.graphics);
    });‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Re: How to list all polygons in the feature layer?

Valgenmap — Tue, 05 Mar 2019 04:46:12 GMT

Is it possible to get the list of features before adding it on Map?

By using some AJAX or something.

Re: How to list all polygons in the feature layer?

RobertScheitlin__GISP — Tue, 05 Mar 2019 15:02:57 GMT

Valgen,

Use esriRequest to make a service call to the rest endpoint for the MapService or FeatureService, with a query where of 1=1.

Here is a sample that shows that:

Request layer info | ArcGIS API for JavaScript 3.27