problem setting FeatureLayer Where property at run time in code behind

markcheyne

Hi - My app includes a feature layer. The app starts with all features in the layer shown. Later, I give the user a chance to restrict the features to a particular set, I do this by resetting the layer's Where property in a method in the code-behind, like this:

FeatureLayer siteLayer = Map.Layers["Sites"] as FeatureLayer;
siteLayer.Where = "PROPERTY_ID = 123";

This should cause all but one feature to disappear from the map. But nothing happens, the map appears unchanged.

Seeing http://forums.esri.com/Thread.asp?c=213&f=2455&t=299876 I add another line:

siteLayer.Update();

This causes all features in the map to be cleared. Further, If I try to do anything else in this method with the siteLayer reference (like get its extent so I can zoom to it), I now get a null reference exception.

I see from http://forums.arcgis.com/threads/40125-Is-there-a-feature-layer-quot-completed-quot-event that maybe I should wait to interact with the layer again until that event fires. It doesn't explain however why I either get no change in my map, or all my features disappear.

I also see the developer in that second post is doing something like removing and readding the layer. Is that necessary in my case, seems odd?

Ideas?

MC

DominiqueBroux

It doesn't explain however why I either get no change in my map,

That's normal. You need to call Update after changing the Where clause. 'Update' will reexecute the request.

or all my features disappear.

I don't explain either, except obviously if your request returns nothing.
Are you sure that your criteria "PROPERTY_ID = 123" is supposed to return something?
You can test your query directly in your browser or use fiddler to look at the request sent, that should give a clue.