FieldCount from iTable .NET c#?

Question

I'm trying to get a message box to display some simple counts of layers and fields. Everything works fine until I add in the code to get the field count of composite layers. Below is the code for my button click event which populates the message box, and the error message I am receiving.

private void buttonCountLayers_Click(object sender, EventArgs e)
 {
 //count the point/line/poly/raster feature layers
 int groupcount = 0;
 int pointcount = 0;
 int linecount = 0;
 int polycount = 0;
 int rastercount = 0;
 string subfields = "";
 int subfieldcount = 0;

 for (int i = 0; i < layercount; i++)
 {
 ILayer pLayer = pMap.get_Layer(i);
 string name = pLayer.Name;
 pointcount = pointcount + PointLayerTest(pLayer); //returns 1 if layer has point geometry
 linecount = linecount + LineLayerTest(pLayer);
 polycount = polycount + PolygonLayerTest(pLayer);
 rastercount = rastercount + RasterLayerTest(pLayer);
 if (pLayer is ICompositeLayer)
 {
 ICompositeLayer pCompLayer = pLayer as ICompositeLayer; //QI
 int sublayern = pCompLayer.Count;
 for (int j = 0; j < sublayern; j++) //go through group layer
 {
 ILayer pLayer2 = pCompLayer.get_Layer(j);
 groupcount = groupcount + GroupLayerTest(pLayer2);
 pointcount = pointcount + PointLayerTest(pLayer2);
 linecount = linecount + LineLayerTest(pLayer2);
 polycount = polycount + PolygonLayerTest(pLayer2);
 rastercount = rastercount + RasterLayerTest(pLayer2);
 IFeatureLayer2 pFeatureLayer = (IFeatureLayer2)pLayer2;
 ITable subLayers = (ITable)pFeatureLayer;
 subfieldcount = subLayers.Fields.FieldCount; //this line throws the error
 subfields = subfields + Environment.NewLine + pLayer2.Name + ":" + subfieldcount;
 }
 }
 }
 //show all counts in pop-up window
 MessageBox.Show("number of group layers:"+groupcount+ Environment.NewLine +"point layers:"+pointcount+
 Environment.NewLine+"line layers:"+linecount+Environment.NewLine+"polygon layers:"+polycount+
 Environment.NewLine+"raster layers:"+rastercount+Environment.NewLine+Environment.NewLine+subfields);
 }

ERROR MESSAGE: An unhandled exception of type 'System.Runtime.InteropServices.COMException' occurred in projectname.dll

Additional information: Error HRESULT E_FAIL has been returned from a call to a COM component.

Answer 1

It's difficult to tell not knowing what layers you are in your map, but this code: rastercount = rastercount + RasterLayerTest(pLayer2); makes it look like you are expecting an IRasterLayer.

I do not believe you can get an IFeatureLayer from a Raster layer. Try testing for IRasterLayer and skip over it.

• Michael Stimson: Also ILayer.Valid resources.arcgis.com/en/help/arcobjects-net/componenthelp/… - broken layers can mess up good code.. check the layer is valid before typeof(pLayer2) is IFeatureLayer or IStandaloneTable (both support IFields)