How to read empty cell value using EXCEL interop api in C # .net?

Question

I get a System.com_object error if I try to read an EXCEL cell that is empty. My code is:

public static List<OrderPC> getFilters(string fileCheckout) { List<OrderPC> orderPCs = new List<OrderPC>(); XLDoc sldoc = new XLDoc(); string localPath = @"C:\Temp\PCs.xlsx"; Microsoft.Office.Interop.Excel.Application oXL=null; Microsoft.Office.Interop.Excel.Workbook mWorkBook=null; Microsoft.Office.Interop.Excel.Worksheet mWSheet1=null; Microsoft.Office.Interop.Excel.Range xlRange=null; try { oXL = new Microsoft.Office.Interop.Excel.Application(); mWorkBook = oXL.Workbooks.Open(localPath); mWSheet1 = mWorkBook.Sheets[1]; xlRange = mWSheet1.UsedRange; foreach (Microsoft.Office.Interop.Excel.Hyperlink hl in xlRange.Hyperlinks) { int y = hl.Range.Column; int z = hl.Range.Row; string vFilter = mWSheet1.Cells[z, y + 1].Value2.Trim(); if (vFilter.CompareTo("Weekly") == 0) { String baseUri = "http://xxx.yyy.net?"; int followUpIndex = baseUri.Length; OrderPC orderPc = new OrderPC(); orderPc.ProductClass = hl.TextToDisplay.Trim(); orderPc.HyperLink = hl.Address.Trim().Substring(followUpIndex); orderPc.SpecType = mWSheet1.Cells[z, y - 1].Value2.Trim(); if (mWSheet1.Rows[z].Cells[y + 3] != null || mWSheet1.Rows[z].Cells[y + 3].Value2 != string.Empty) { orderPc.ManufactureDate = mWSheet1.Cells[z, y + 3].Value2.ToString(); //Here is the error** } //Console.WriteLine(orderPc.ProductClass+"----"+orderPc.HyperLink); orderPCs.Add(orderPc); } } } catch (Exception ex) { } finally { GC.Collect(); GC.WaitForPendingFinalizers(); Marshal.FinalReleaseComObject(xlRange); Marshal.FinalReleaseComObject(mWSheet1); mWorkBook.Close(Type.Missing, Type.Missing, Type.Missing); Marshal.FinalReleaseComObject(mWorkBook); oXL.Quit(); Marshal.FinalReleaseComObject(oXL); } return orderPCs; } 

This excel file has 10 columns, and I assume that I am reading a valid cell. Mistake: **

{Microsoft.CSharp.RuntimeBinder.RuntimeBinderException: Cannot perform runtime binding on a null reference
at CallSite.Target(Closure , CallSite , Object )
at System.Dynamic.UpdateDelegates.UpdateAndExecute1[T0,TRet](CallSite site, T0 arg0)

"** I have no clue since its com. Help is greatly appreciated.

Answer 1

Add another check

 if (mWSheet1.Cells[z, y + 3].Value2 != null) 

or convert to string using the following code because it will not fail if Value2 is null

 orderPc.ManufactureDate = Convert.ToString(mWSheet1.Cells[z, y + 3].Value2);