topic Re: Lang.Hitch selectFeatures in featureCollection in ArcGIS JavaScript Maps SDK Questions

Lang.Hitch selectFeatures in featureCollection

ThaoLe1 — Tue, 24 Oct 2017 19:30:18 GMT

I have these codes. I'm wondering how do I use Lang.Hitch for this because of this error TypeError: Cannot read property 'selectFeatures' of undefined.

function CreateGraphics (evt) {

CODES HERE.......................

var graphics5= new Graphic(geoBuffer, symbolBuffer, attr5, infoTemplate5);
//map.graphics.add(graphics5);
ShowSelectedFeatures (graphics5);
}

/////////////////////////////////////////////////////////////////////////////////////

function ShowSelectedFeatures(graphicsLine) {

FLayer.setSelectionSymbol(lineSymb);
map.addLayer(FLayer);

}

//////////////////////////////////////////////////////////////////////////////////////

FLayer.selectFeatures(query, FeatureLayer.SELECTION_NEW, function (evt) {

CODES HERE .................................

});

Re: Lang.Hitch selectFeatures in featureCollection

RobertScheitlin__GISP — Sat, 11 Dec 2021 20:34:46 GMT

Thao,

It looks like your FLayer is a local var inside of the ShowSelectedFeatures function and that your call to FLayer.selectFeatures is outside of that functions scope. So in that case the FLayer is always going to be null unless you declare the FLayer var higher in your apps scope. So you need to declare the FLayer var at the begining of your app and then inside the ShowSelectedFeatures you would just use

// Create a new feature layer
FLayer = new FeatureLayer(featureCollection, {‍‍

Re: Lang.Hitch selectFeatures in featureCollection

ThaoLe1 — Sat, 11 Dec 2021 20:34:49 GMT

Hi Robert,

I declared a global variable at the beginning of the app

var FLayer;

and inside ShowSelectedFeatures() I used your suggestion. Still same error.

// Create a new feature layer
FLayer = new FeatureLayer(featureCollection, {

Re: Lang.Hitch selectFeatures in featureCollection

RobertScheitlin__GISP — Tue, 24 Oct 2017 20:28:54 GMT

Thao,

I would have to see more of your code then.

Re: Lang.Hitch selectFeatures in featureCollection

thejuskambi — Tue, 24 Oct 2017 20:39:59 GMT

The error message is indicating that the Flayer variable is not initialized at the time the selectFeatures is called. You need ensure that the Flayer is initialized and or loaded on the the map before selecting features from it.

I would suggest to move the selectFeatures code in ShowSelectedFeatures method and also call it after the layer is loaded/added to map event.

Re: Lang.Hitch selectFeatures in featureCollection

ThaoLe1 — Tue, 24 Oct 2017 20:54:31 GMT

Robert, could you verify the ShowSelectedFeatures() function for featureCollection and its syntax is reasonably correct?

Re: Lang.Hitch selectFeatures in featureCollection

RobertScheitlin__GISP — Wed, 25 Oct 2017 00:02:15 GMT

Thao,

I am not sure a FeatureLayer created from a FeatureCollection supports the selectFeature method. I will test some and get back with you.

Re: Lang.Hitch selectFeatures in featureCollection

RobertScheitlin__GISP — Wed, 25 Oct 2017 00:06:45 GMT

Thao,

So geometry based queries work fine but a query that uses a where clause is not supported.