Does a certain layer exist in map?

[BrianBulla]

Hi,

What is the best way to determine if a layer exists or not?  I have some code that runs on a specific layer, but I don't want Arc to crash if the layer doesn't exist when the user presses the button.

Can anyone suggest a check to go through before the code below runs that will check for the layers existence?  I would think evaluating MapView.Active.Map.FindLayers("GISWRKS1.WORKS.VLS_Points") to a boolean would work, but I can't seem to get it to.

                var vlsLayer = MapView.Active.Map.FindLayers("GISWRKS1.WORKS.VLS_Points").First() as BasicFeatureLayer;

                var selection = vlsLayer.GetSelection();

                IReadOnlyList<long> selectedOIDs = selection.GetObjectIDs();  //save the selected OBJECTIDs to a list.

Thanks!

[BrianBulla]

Hi,

For anyone interested, this seems to work.  If you know of another way, please post it below.

IEnumerable<Layer> layerCheck = MapView.Active.Map.GetLayersAsFlattenedList().Where(l => l.Name.IndexOf("GISWRKS1.WORKS.VLS_Points", StringComparison.CurrentCultureIgnoreCase) >= 0);

int count = layerCheck.OrderBy(l => l).Count();

if (count < 1)

{

ArcGIS.Desktop.Framework.Dialogs.MessageBox.Show("Please add the VLS Layer to the map.", "Missing Layer");

return;

}

[UmaHarano · Accepted solution]

Hi,

These are a few ways to check for a layer:

//Finds a layer using a URI.
//The Layer URI you pass in helps you search for a specific layer in a map
var lyrFindLayer = MapView.Active.Map.FindLayer("CIMPATH=map/u_s__states__generalized_.xml"); 

//This returns a collection of layers of the "name" specified. You can use any Linq expression to query the collection.  
var lyrExists = MapView.Active.Map.GetLayersAsFlattenedList().OfType<FeatureLayer>().Any(f => f.Name == "U.S. States (Generalized)");

//Finds layers by name and returns a read only list of Layers
var lyr = MapView.Active.Map.FindLayers("U.S. States (Generalized)").FirstOrDefault();‍‍‍‍‍‍‍‍‍

Thanks

Uma