topic Re: Unselect/clear a feature from a feature layer using a query in ArcGIS JavaScript Maps SDK Questions

Unselect/clear a feature from a feature layer using a query

Jackson_CountyMissouri — Tue, 27 Jul 2021 18:03:28 GMT

This is sort-of a follow-up to my thread here:

https://community.esri.com/t5/arcgis-api-for-javascript-questions/querying-one-feature-layer-to-use-to-query-another/m-p/1076044#M73742

I'm now trying to do the opposite: I need to unselect/clear an already selected feature in a feature layer, using a query or anything else besides getting the Popup involved. I have looked through the 4.X API as well as some examples on this board, but can't find anything that works. In the API for FeatureLayerView.highlight there is a snippet that uses highlight.remove(), but every time I try to use it, my developer console tells me that the .remove() is not a function, which doesn't surprise me because there is no .remove function anywhere I can find in the API.

I am trying to do something like this. FYI the myVariable variable is something I've already retrieved earlier that will represent the feature that's been highlighted.

As I said, the .remove() does not work, and I've tried all kinds of different iterations of it, to no avail. I've also tried putting the queryFeatures inside of the whenLayerView and all kinds of other arrangements, but since my selecting-the-feature function works fine and all I want to do is the reverse of that, it seems like I should just be able to make a minor change to that selecting-the-feature code - right? I can't believe they have a "highlight" function but no "clear" or "un-highlight" function.

Re: Unselect/clear a feature from a feature layer using a query

Tim_McGinnes — Tue, 27 Jul 2021 20:21:30 GMT

According to the highlight function it returns a handler that you can use to remove the highlight. There is also a good sample showing how it works: Highlight point features

First you setup a variable to hold the highlight selection handler:

let highlightSelect;

Then when you do a query you can remove the current highlight before doing the new one (you can see where it is assigning the handler to highlightSelect in line 11):

myLayer.queryFeatures(myQuery).then((result) => { // if a feature is already highlighted, then remove the highlight if (highlightSelect) { highlightSelect.remove(); } // the feature to be highlighted const feature = result.features[0]; // use the objectID to highlight the feature highlightSelect = layerView.highlight( feature.attributes["OBJECTID"] );

You could also just remove the highlight any time you wish:

highlightSelect.remove();

Re: Unselect/clear a feature from a feature layer using a query

Jackson_CountyMissouri — Tue, 27 Jul 2021 21:11:47 GMT

I've already tried that. My feature is already selected before I even enter my function. If I try to just do ...

if(highlightSelect) highlightSelect.remove();

... it has no idea what highlightSelect is. So I have to define it beforehand ... somehow. I could try this:

... but of course that doesn't work because I'm passing in a query to myLayer.queryFeatures that isn't even declared or defined yet. So I next try this:

Which gives me the error message: "TypeError: highlightSelect.remove is not a function." Which is what I mentioned in my first post here.

Re: Unselect/clear a feature from a feature layer using a query

Tim_McGinnes — Tue, 27 Jul 2021 22:02:13 GMT

You need to define the variable outside the functions in the main code (sort of like a global variable). The highlightSelect variable will know what feature was highlighted, so you don't need to query it again in the unselect function.

let highlightSelect; function selectParcel() { //Query feature first highlightSelect = layerView.highlight(feature.attributes["OBJECTID"]); } function unselectParcel() { if(highlightSelect) highlightSelect.remove(); }

Re: Unselect/clear a feature from a feature layer using a query

Jackson_CountyMissouri — Tue, 27 Jul 2021 22:03:57 GMT

Still getting the "TypeError: highlightSelect.remove is not a function" error message. However, at least it's clearing the newest selected feature instead of the one I want to be selected (which is the previous selected feature), so maybe at least it's doing *something*

Re: Unselect/clear a feature from a feature layer using a query

Tim_McGinnes — Tue, 27 Jul 2021 22:14:53 GMT

If all you want to do is remove the previous highlight when doing a new query then try this (note: nu unselect function):

let highlightSelect; function selectParcel() { //Remove highlights if (highlightSelect) { highlightSelect.remove(); } //Query feature first highlightSelect = layerView.highlight(feature.attributes["OBJECTID"]); }

If it's a more complicated scenario than that, then you may have to post some more complete code.

I recommend having a play around with that highlight point features sample I posted earlier.