SpatialQueryFilter

[BrianBulla]

Hi,

I'm trying to do a spatial query on a layer in my map.  In my code, I first check to see if the layer is there:

IEnumerable<Layer> gridLayer = map.GetLayersAsFlattenedList().Where(l => l.Name.IndexOf("GISWRKS1.WORKS.LAND_Grid", StringComparison.CurrentCultureIgnoreCase) >= 0);

if (gridLayer.Count() == 0)
{
ArcGIS.Desktop.Framework.Dialogs.MessageBox.Show("Please add the GRID layer before proceeding.", "Missing Layer");
return;
}

Later in the code I want to use a point to intersect the gridLayer using this code:

SpatialQueryFilter spatialFilter = new SpatialQueryFilter();
spatialFilter.FilterGeometry = intersectPoint;
spatialFilter.SpatialRelationship = SpatialRelationship.Intersects;
spatialFilter.SubFields = "GRIDNO";

FeatureLayer grid = (FeatureLayer)gridLayer;        //This does not work.   Null Reference Exception or sometimes an InvalidCast, depending on what I am doing.  How do I turn my gridLayer from above into something I can use to query??  I've tried many different things...FeatureLayer, BasicFeatureLayer, FeatureClass.....nothing works.

RowCursor gridCursor = grid.Search(spatialFilter);
while (gridCursor.MoveNext())
{
using (Feature feature = (Feature)gridCursor.Current)
{
ArcGIS.Desktop.Framework.Dialogs.MessageBox.Show(feature[0].ToString());
}
}

[NarelleChedzey · Accepted solution]

Brian, 

The first line of your code defines gridLayer as a IEnumerable<Layer>  ... you cannot cast an enumeration to a class that expects a single object. 

It would be better if the line was something similar to this

Layer gridLayer = map.GetLayersAsFlattenedList().Where(l => l.Name.IndexOf("GISWRKS1.WORKS.LAND_Grid", StringComparison.CurrentCultureIgnoreCase) >= 0).FirstOrDefault();

then you can check gridLayer against null to determine if it exists.  Finally you can then do 

FeatureLayer grid = gridLayer as FeatureLayer;

Alternatively you could also do this

FeatureLayer gridLayer = map.GetLayersAsFlattenedList().OfType<FeatureLayer>().Where(l => l.Name.IndexOf("GISWRKS1.WORKS.LAND_Grid", StringComparison.CurrentCultureIgnoreCase) >= 0).FirstOrDefault();

[BrianBulla]

Ah yes, that makes sense to me now.  Thanks for helping!!