topic Re: Get FeatureLayer from Map in ArcGIS JavaScript Maps SDK Questions

Get FeatureLayer from Map

PaulGiard — Thu, 26 Jul 2018 18:04:00 GMT

I am a little stuck here and I hope someone can point me to the right place.

Using the ArcGIS-js-api in Angular / Typescript

I am able to display a WebMap via an internal Portal instance.

I can access the Layers that the Map is composed of but I am unable to get the layer as a featureLayer.

All of the examples I see are adding a featureLayer to the map.

How can I get a featureLayer from the Map?

RobertScheitlin__GISP — Sat, 11 Dec 2021 09:18:07 GMT

Paul,

If you are taking 3.x then it is as simple as:

var incidentLayer = map.getLayer("incidentLayer");
‍

This assumes you know the id of the layer.

PaulGiard — Thu, 26 Jul 2018 19:56:10 GMT

Thanks for the response,

I am using 4.8 and there is no getLayer method on the Map

RobertScheitlin__GISP — Thu, 26 Jul 2018 20:05:46 GMT

Paul,

Be sure to add a tag to your post or some text stating the API version your are targeting.

So in 4.x when using a WebMap you just use the WebMaps findLayerById

PaulGiard — Thu, 26 Jul 2018 20:26:22 GMT

I did try that and I get the same issue as when I loop through the Layer Collection

FindLayerById returns a Layer and I don't know how to cast to a FeatureLayer

Type 'Layer' is not assignable to type 'FeatureLayer'.
Property 'capabilities' is missing in type 'Layer'.

RobertScheitlin__GISP — Thu, 26 Jul 2018 20:48:02 GMT

Paul,

Is it really a FeatureLayer in the Web Map then? Are you sure it is not a Whole MapService and thus a MapImageLayer?

PaulGiard — Thu, 26 Jul 2018 20:52:21 GMT

When I loop through the layers the type is feature

Our C# code on Xamarin with the .Net API autocasts the same layer as expected.

RobertScheitlin__GISP — Thu, 26 Jul 2018 21:35:10 GMT

Paul,

If that is the case then when you use findLayerById then the returned layer will already be a FeatureLayer class.

PaulGiard — Fri, 27 Jul 2018 15:10:39 GMT

It looks like it is a problem with Typings. The code works when casting directly:

const featureLayer: esri.FeatureLayer = this.mapView.map.findLayerById('69bf94b82f1a4ff8b7afcf370b8c00db') as esri.FeatureLayer;

diaconori — Thu, 10 Jun 2021 08:33:01 GMT

Isn't there a way to do this without providing the value through a hard-coded string?

Something like:

var layers = this.map.getLayers(); // process layers in a for-each loop...