Are layers in the map??

BrianBulla

I'm trying to determine if specific layers are in the map before proceeding with more code.  The following produces an error at the line where I am checking to the value == null of each layer.  

Is this the best way to do this?  Or is there a better way to check for specific layers in the map??

protected override void OnClick()
{
var gridLayer = MapView.Active.Map.FindLayers("GISWRKS1.WORKS.LAND_Grid").FirstOrDefault() as BasicFeatureLayer;
var localMunicipalityLayer = MapView.Active.Map.FindLayers("GISWRKS1.WORKS.LAND_LocalMunicipality").FirstOrDefault() as BasicFeatureLayer;
var administrativeAreaLayer = MapView.Active.Map.FindLayers("GISWRKS1.WORKS.LAND_AdministrativeArea").FirstOrDefault() as BasicFeatureLayer;
var communitiesLayer = MapView.Active.Map.FindLayers("GISWRKS1.WORKS.LAND_Communities").FirstOrDefault() as BasicFeatureLayer;
var depotAreaLayer = MapView.Active.Map.FindLayers("GISWRKS1.WORKS.LAND_DepotArea").FirstOrDefault() as BasicFeatureLayer;
var pressureZoneLayer = MapView.Active.Map.FindLayers("GISWRKS1.WORKS.LAND_PressureZone").FirstOrDefault() as BasicFeatureLayer;

****This is where I get the error!!  If I check these one at a time, it works, but when combining with the || is when the error happens.  In ArcMap 10.2, I have similar code running with no problems.****

if ((gridLayer == null) || (localMunicipalityLayer == null) || (administrativeAreaLayer == null) || (communitiesLayer == null) || (depotAreaLayer == null) || (pressureZoneLayer = null))
{
ArcGIS.Desktop.Framework.Dialogs.MessageBox.Show("Please add the LAND and Water Pressure Zone layers before proceeding.");
return;
}

ArcGIS.Desktop.Framework.Dialogs.MessageBox.Show("All the layers are there!!");

}

BrianBulla

OK.  It looks like the problem is a C# issue with the || operator and those null values.  Not exactly sure why, but this seems to fix the problem:

Map map = MapView.Active.Map;
IEnumerable<Layer> gridLayer = map.GetLayersAsFlattenedList().Where(l => l.Name.IndexOf("GISWRKS1.WORKS.LAND_Grid", StringComparison.CurrentCultureIgnoreCase) >= 0);
IEnumerable<Layer> localMunicipalityLayer = map.GetLayersAsFlattenedList().Where(l => l.Name.IndexOf("GISWRKS1.WORKS.LAND_LocalMunicipality", StringComparison.CurrentCultureIgnoreCase) >= 0);
IEnumerable<Layer> administrativeAreaLayer = map.GetLayersAsFlattenedList().Where(l => l.Name.IndexOf("GISWRKS1.WORKS.LAND_AdministrativeArea", StringComparison.CurrentCultureIgnoreCase) >= 0);
IEnumerable<Layer> communitiesLayer = map.GetLayersAsFlattenedList().Where(l => l.Name.IndexOf("GISWRKS1.WORKS.LAND_Communities", StringComparison.CurrentCultureIgnoreCase) >= 0);
IEnumerable<Layer> depotAreaLayer = map.GetLayersAsFlattenedList().Where(l => l.Name.IndexOf("GISWRKS1.WORKS.LAND_DepotArea", StringComparison.CurrentCultureIgnoreCase) >= 0);
IEnumerable<Layer> pressureZoneLayer = map.GetLayersAsFlattenedList().Where(l => l.Name.IndexOf("GISWRKS1.WORKS.WAT_PressureZone", StringComparison.CurrentCultureIgnoreCase) >= 0);

if (gridLayer.Count() == 0 || localMunicipalityLayer.Count() == 0 || administrativeAreaLayer.Count() == 0 || communitiesLayer.Count() == 0 || depotAreaLayer.Count() == 0 || pressureZoneLayer.Count() == 0)
{
ArcGIS.Desktop.Framework.Dialogs.MessageBox.Show("Please add the LAND and Water Pressure Zone layers before proceeding.", "Missing Layers");
return;
}