Conditionally uploading Excel SpreadSheet using FileUpload - asp.net

Question

Below Is my Vb Code which is getting the row count of the excel file. However, i want to throw an exception and give an error message if the row count is greater than 10k rows. How would i be able to do that? I have done my research on getting the row count but not sure how to throw an exception. The following is an ASP.Net Windows Form Application.
Dim xls As New Excel.Application
Dim sheet As Excel.Worksheet
Dim filePath As String = Path.Combine(GlobalVariable.savedPath, GlobalVariable.excelFileName)
xls.Workbooks.Open(filePath)
sheet = xls.ActiveWorkbook.Sheets(1)
Dim maxSize As Integer = 2
Dim row As Integer = 1
Do Until sheet.Cells(row, 1).value Is Nothing
row += 1
Loop
MsgBox("last Row is " & row - 1)
xls.Workbooks.Close()
xls.Quit()
releaseObject(sheet)
releaseObject(xls)

Answer 1

You are already counting the rows, so you can modify your loop to continue only while row is less then 10,000.
Dim row As Integer = 1
Do
row += 1
Loop while sheet.Cells(row, 1).value IsNot Nothing AndAlso row <= 10000
This will loop, incrementing row until there are no more rows, or if you hit 10,000. You can then check if row is 10,000 to decide if you want to show an error message.
If row >= 10000 then
MsgBox("Over 10000 rows")
'If you want to throw an actual exception you can do:
Throw new Exception("Over 10000 rows")
Else
MsgBox("last Row is " & row - 1)
End If
Updated to reflect OP Question Updates:
I don't know if I would recommend throwing an exception to handle if row reaches 10,000. Instead I would do like so:
Private Sub BtnUpload_OnClick(sender As Object, e As EventArgs) Handles BtnUplaod.Click
REM Save SpreadSheet
Dim filePath As String = Path.Combine(GlobalVariable.savedPath, GlobalVariable.excelFileName)
myfileUploader.saveAs(filePath)
REM Open SpreadSheet
Dim xls As New Excel.Application
Dim sheet As Excel.Worksheet
xls.Workbooks.Open(filePath)
sheet = xls.ActiveWorkbook.Sheets(1)
Dim maxSize As Integer = 2
REM Loop through spreadsheet and count rows
Dim row As Integer = 1
Do
row += 1
Loop While sheet.Cells(row, 1).value IsNot Nothing AndAlso row <= 10000 'Exit loop when end of SpreadSheet is reached or if rows exceeds 10,000
REM Release Resources
xls.Workbooks.Close()
xls.Quit()
releaseObject(sheet)
releaseObject(xls)
REM Decide whether to accept upload, or reject and show error
If row >= 10000 Then 'If row > 10000 delete file and show error
REM Delete the file
File.Delete(filePath)
REM Show some sort of error to user - Its up to you how you want to do so. That is a seperate question
MsgBox("Your Error")
REM Else SpreadSheet is valid
Else
'Your Code code doing what you want with spreadsheet goes here
MsgBox("last Row is " & row - 1)
End If
End Sub
This code will run when the users clicks a button called BtnUpload on the WebPage. You can put it anywhere you like though.
I think this is what you want. Is that correct?