topic Re: [JSAPI 4.6][FeatureLayer] LayerView.queryExtent Error in ArcGIS JavaScript Maps SDK Questions

[JSAPI 4.6][FeatureLayer] LayerView.queryExtent Error

QiZhao — Thu, 05 Apr 2018 22:08:30 GMT

I'm trying to queryExtent with a layer view. Instead of getting the extent, I got a strange exception:

The code is very simple:

function executeQuery(lyrView) {
console.log("Querying extent begin");

lyrView.queryExtent()
.then(function(result){ console.log(result); })
.catch(function(e){ console.error(e); });
console.log("Querying extent end");
}

Here is an running example: FeatureLayer LayerView QueryExtent

It seems that this issue only happenes on point-based feature layers. lyrView.queryExtent works as expected on polygon feature layers. Maybe it's a bug?

Re: [JSAPI 4.6][FeatureLayer] LayerView.queryExtent Error

RalucaNicola1 — Wed, 18 Apr 2018 16:29:12 GMT

Hi Qi,

that is indeed a bug on our side. We'll fix this for 4.8. Can you tell me what you're trying to achieve, maybe we can suggest a workaround until then.

Raluca

Re: [JSAPI 4.6][FeatureLayer] LayerView.queryExtent Error

QiZhao — Sat, 11 Dec 2021 20:31:30 GMT

Hi Raluca,

Thank you for looking into this. I'm glad to know that this issue is confirmed and will be fixed in the future. We are trying to change the map view to the extent of feature layer graphics that are shown.

Using this page as an example: every time when user select a different "Well Type", a query is performed, and only a subset of features will be shown as query result. We want the map view automatically "go to" the result features.

We've implemented a workaround queryExtent function:

function queryExtent(lyrView) {
    var deferred = new Deferred();
    lyrView.queryExtent().then(function(result) {
        //queryExtent works well for polyline and polygon layers
        deferred.resolve(result);
      
    }).catch(function() {
        //queryExtent doesn't work for point layers
        return lyrView.queryFeatures();
      
    }).then(function(feature) {
        //calculate extent by ourselves
        var result = { count: 0, extent: null };
        if (!feature || !feature.length)
            return deferred.resolve(result);

        //all features are points
        var xMin = features[0].geometry.x,
            xMax = xMin,
            yMin = features[0].geometry.y,
            yMax = yMin;
      
        for (var feature of features) {
            var x = feature.geometry.x,
                y = feature.geometry.y;
          
            if (x < xMin) xMin = x;
            if (x > xMax) xMax = x;
            if (y < yMin) yMin = y;
            if (y > yMax) yMax = y;
        }
      
        require(['esri/geometry/Extent'], function(Extent) {
            result.count = features.length;
            result.extent = new Extent({
                xMin: xMin,
                xMax: xMax,
                yMin: yMin,
                yMax: yMax,
                spatialReference:
                    features[0].geometry.spatialReference
            });
          
            deferred.resolve(result);
        };
    });
      
    return deferred;
}‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

This function returns the same type of promise with lyrView.queryExtent function:

Returns:

Type

Description

Promise<Object>

When resolved, returns the extent and count of the features that satisfy the input query. See the object specification table below for details.

Property	Type	Description
count	Number	The number of features that satisfy the input query.
extent	Extent	The extent of the features that satisfy the query.

Re: [JSAPI 4.6][FeatureLayer] LayerView.queryExtent Error

RalucaNicola1 — Fri, 20 Apr 2018 14:13:31 GMT

Hi Qi,

awesome, sorry that you had to work around things to make it work. Next release it will be fixed and you can go back to normal workflow.

One thing I thought about: is it really mandatory that you query the layer view? I tried it out and querying the extent on the layer works.

Best,

Raluca

Re: [JSAPI 4.6][FeatureLayer] LayerView.queryExtent Error

QiZhao — Fri, 20 Apr 2018 16:31:02 GMT

Hi Raluca,

It's not mandatory for us to use queryExtent on layer view. To my understanding, query on layer will run on server-side, while query on layer view will run on browser-side. Since all the graphics I need are already shown in browser, I just thought query on layer view may have better performance than query on layer. Thanks.

Best,

Qi Zhao

Re: [JSAPI 4.6][FeatureLayer] LayerView.queryExtent Error

RalucaNicola1 — Mon, 23 Apr 2018 11:07:01 GMT

ok, I see. Yes, that makes sense to spare the requests. In 4.8 you can remove the workaround, sorry again about the bug..