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.

[markcheyne]

Hi, I really appreciate the feedback, thank you.

New day, fresh mind, I've got it sorted. Turns out I had a bug elsewhere. FYI, this is all that is necessary to immediately make the map filter its visible contents to the desired features:

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

Thanks, MC

[DominiqueBroux]

Strange!!.
My best bet at this time is that your where clause is not working.
Could you use fiddler to look at the request sent?
Also could you try with a where clause 100% garantee such as "1=1"?

I tested with the Feature Layers Simple sample.
When I execute these lines of code:

  var featureLayer = MyMap.Layers["MyFeatureLayer"] as FeatureLayer;
   featureLayer.Where = "POP1990 > 50000";
   featureLayer.Update();

a new request is sent to the server and more cities are displayed (initial criteria was > 100000).


Note : I just noticed I had inversed 'Refresh' and 'Update' in my previous post. I fixed that.

[JerryBiedenbender]

I am trying to do this same thing and every time I run my map It displays nothing. The code I am using is.

FeatureLayer siteLayer = MyMap.Layers["Dispatch"] as FeatureLayer;
            siteLayer.Where = "Status = Complete";
            siteLayer.Update();

My goal is actually to display everything that is not complete so I also tried

FeatureLayer siteLayer = MyMap.Layers["Dispatch"] as FeatureLayer;
            siteLayer.Where = "Status <> Complete";
            siteLayer.Update();

Neither of these work.

I also tried adding a where clause on the MainPage.xaml

<esri:FeatureLayer  DisableClientCaching="True" Where="Status = Complete" ID="Dispatch"   OutFields="*" x:Name="Dispatch"  MouseLeftButtonUp="FeatureLayer_MouseLeftButtonUp" Mode="OnDemand"   SelectionColor="Cyan"   Visible="True" Url="http://gis02/ArcGIS/rest/services/FeatureServices/Dispatch/FeatureServer/0"/>

This also did not work, It gave me a blank map.


Any advice on this?

Thanks,
Jerry

[markcheyne]

jerry - your experience seems to suggest problems with the Where expression? While I was troubleshooting, if I put my Where expression into the layer's XAML, I'd see what I wanted. Maybe confirm in ArcMap that your Where expression works on that layer?

Also, try removing the DisableClientCaching property, and set the layer Mode to "Snapshot"?

[JerryBiedenbender]

I figured it out, I had a coded domain set up on my layer and it wanted the number value instead of the text value