topic Re: IdentifyLayerAsync not returning polygons hidden by DefinitionExpression... in .NET Maps SDK Questions

IdentifyLayerAsync not returning polygons hidden by DefinitionExpression...

StevenMcKenna1 — Tue, 03 Mar 2020 17:50:57 GMT

I'm trying to use the IdentifyLayerAsync function to search for polygons in a layer that I currently have a DefinitionExpression in effect, and it's not returning the polygons that aren't currently visible because of the filter. Is there any way to get around this restriction?

Re: IdentifyLayerAsync not returning polygons hidden by DefinitionExpression...

JoeHershman — Tue, 03 Mar 2020 19:33:38 GMT

Is this online or offline data?

Re: IdentifyLayerAsync not returning polygons hidden by DefinitionExpression...

StevenMcKenna1 — Tue, 03 Mar 2020 19:36:25 GMT

It's online connected to our local portal server. I'm using the .NET Runtime.

Thanks!

Re: IdentifyLayerAsync not returning polygons hidden by DefinitionExpression...

TonyWakim — Wed, 04 Mar 2020 06:15:42 GMT

Steven,

Identify will not return features that are not part of the definition expression on a layer.

One workaround you can try is to have another layer (same data source, no definition expression) but set the layer opacity to 0; since opacity will be ignored with identify... Identify features—ArcGIS Runtime SDK for .NET | ArcGIS for Developers, if you identify features on this new layer you will get the features you want.

In this case you will only see the features returned by the definition expression, but you can identify all the features.

Tony

Re: IdentifyLayerAsync not returning polygons hidden by DefinitionExpression...

StevenMcKenna1 — Wed, 04 Mar 2020 11:55:50 GMT

Why thank you Tony. That is a wonderfully sneaky idea! I'm going to implement this.

Thanks again!

Re: IdentifyLayerAsync not returning polygons hidden by DefinitionExpression...

JoeHershman — Wed, 04 Mar 2020 14:17:34 GMT

Yup I was thinking the same. If they were offline I would say you could toggle the DefinitionExpression off/on. We do for some other things and it isn't noticeable to the user, for something doing a small search

Re: IdentifyLayerAsync not returning polygons hidden by DefinitionExpression...

StevenMcKenna — Wed, 04 Mar 2020 18:05:17 GMT

Actually, oddly enough, I had to set the Opacity to 0.01 for this to work. If I set it to flat zero, the polygons still weren't being returned by the IdentifyLayerAsync function at the given point where the user clicked on the map.

Re: IdentifyLayerAsync not returning polygons hidden by DefinitionExpression...

dotMorten_esri — Mon, 09 Mar 2020 16:11:38 GMT

The map is being smart and not doing work if the layer isn't actually visible. This means it's not actually pulling down data at all in this case. The idea behind identify is you're able to click what you see. If you can't see it, you can't click it.

The alternative is to do a spatial query against that layer instead if using identify.

Re: IdentifyLayerAsync not returning polygons hidden by DefinitionExpression...

StevenMcKenna — Mon, 09 Mar 2020 16:21:20 GMT

Thank you for this suggestion. I already implemented the zero opacity fake layer, but now I'm starting to think your solution might be cleaner (or more efficient, at least).

I'm assuming that I would need to first somehow convert the currently clicked on map position (passed into the GeoTapped event as e.Position) into an actual MapPoint. I think I have the code to do that.

However, which function would I use to perform a spatial query to find out which polygons intersect the MapPoint?

Re: IdentifyLayerAsync not returning polygons hidden by DefinitionExpression...

dotMorten_esri — Mon, 09 Mar 2020 17:47:19 GMT

The GeoTapped event also has e.Location which will give you the MapPoint 😉
How you query a layer depends on the layer type. If it's a feature layer, you'd get it's FeatureTable and use the QueryAsync method.

Re: IdentifyLayerAsync not returning polygons hidden by DefinitionExpression...

StevenMcKenna — Mon, 09 Mar 2020 18:52:15 GMT

I will research the QueryAsync. All my experience thus far has only been using the QueryFeaturesAsync method using WHERE clauses directed at Attribute values. This spatial query stuff will be some new fun for me! I'm hunting for examples now.

Thanks once again for your help.

Re: IdentifyLayerAsync not returning polygons hidden by DefinitionExpression...

JoeHershman — Sat, 11 Dec 2021 19:47:08 GMT

Something along these lines. I always forget what the correct SpatialRelationship is should be either Within or Contains

private async Task<Feature> Query(Map map, MapPoint mapPoint)
{
	FeatureLayer featureLayer = map.OperationalLayers.OfType<FeatureLayer>().First(fl => fl.Name == "MyLayerName");

	var parameters = new QueryParameters {Geometry = mapPoint, SpatialRelationship = SpatialRelationship.Within};
	var results = await featureLayer.FeatureTable.QueryFeaturesAsync(parameters);

	return results.First();
}‍‍‍‍‍‍‍‍‍

Re: IdentifyLayerAsync not returning polygons hidden by DefinitionExpression...

StevenMcKenna — Mon, 09 Mar 2020 19:16:03 GMT

Thanks Joe! This community is beyond helpful!

Re: IdentifyLayerAsync not returning polygons hidden by DefinitionExpression...

StevenMcKenna — Fri, 13 Mar 2020 13:45:38 GMT

I have a follow-up question....

Although the QueryFeaturesAsync method you provided a wrapper function for works well and returns the feature that the given MapPoint is within, it isn't returning the feature with all the attributes populated (only the first two out of 27 are loaded). This is causing an error "The given key was not present in the dictionary" when I go to retrieve or update the values. I looked at all the QueryParameter properties, and I couldn't locate any that tell it to load all the attributes upon running the query. I tried the one that tells it to load the geometry, but that didn't solve the issue.

Re: IdentifyLayerAsync not returning polygons hidden by DefinitionExpression...

JoeHershman — Fri, 13 Mar 2020 15:37:29 GMT

await feature.LoadAsync()‍

https://community.esri.com/thread/236680-get-attributes-from-featurelayergetselectedfeaturesasync

By design all attributes are not returned when a ServiceLayer is queried in order to reduce the data coming across the wire

Re: IdentifyLayerAsync not returning polygons hidden by DefinitionExpression...

StevenMcKenna — Fri, 13 Mar 2020 15:44:27 GMT

That worked, thanks once again Joe!

-Steve