VB.NET - Working with Excel and cannot release files once complete - excel

Question

I created an app that does the following:
Opens an excel spreadsheet and show a hidden sheet
Copy the data in this sheet to a temporary spreadsheet
Run some error checks on the data that's been pasted
Create a unique code in the first column based on customer no. date & time
Save the spreadsheet as a new file
Clear up to be ready for the next spreadsheet
The problem I am having is at step 6 of clearing up and releasing any excel objects in memory that can hold up moving to the next spreadsheet and so on.
The current issue I have is that an Excel object remains open and locks the tempfile.xlsx that is created which will then randomly generates the error "The file 'C:\Temp\CustOrders\Input\TempFile.xlsx' already exists." I say randomly because I can run 10 or more files through it without an issue. I could run them all again and it will produce the error after the 1st, 2nd, 3rd or later file. I cannot blame any one file for causing this.
How do I effectively close out all Excel objects ready for the next file to be processed? I have so far tried different ways to do this including trying to kill the process but this seems like a dirty sledgehammer approach.
Here's the code:
Imports Microsoft.Office.Interop.Excel
Imports Microsoft.Office.Interop
Imports System.Runtime.InteropServices
Imports System.IO
Public Class Form1
Dim xlApp As Excel.Application
Dim xlNewApp As Excel.Application
Dim xlWorkBook As Excel.Workbook
Dim xlWorkSheet As Excel.Worksheet
Dim range As Excel.Range
Dim rCnt As Integer
Dim cCnt As Integer
Dim Obj As Object
Dim TempFile() As String
Dim TempFiledir As String
Dim filename As String
Dim xlNewWorkBook As Excel.Workbook
Dim xlNewWorkSheet As Excel.Worksheet
Dim misValue As Object = System.Reflection.Missing.Value
Dim Cust As Object
Dim pfile As String
Dim NoProcessed As Integer = 0
Dim NoFailed As Integer = 0
Dim filecount As Integer = 0
Dim fileremaining As Integer = 0
Dim custFailed As Integer = 0
Dim files() As String = Directory.GetFiles("C:\Temp\CustOrders\Uploaded")
Dim di As New DirectoryInfo("C:\Temp\CustOrders\Uploaded")
Private Sub releaseObject(ByVal obj As Object)
Try
Marshal.ReleaseComObject(obj)
obj = Nothing
Catch ex As Exception
obj = Nothing
Finally
GC.Collect()
End Try
End Sub
Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
lblProcessingFile.Visible = False
CountFiles()
lblFileCount.Text = "Files to be processed: " & filecount
End Sub
Function CountFiles()
Dim files() As String = Directory.GetFiles("C:\Temp\CustOrders\Uploaded")
Dim di As New DirectoryInfo("C:\Temp\CustOrders\Uploaded")
If files.Count > 0 Then
filecount = di.GetFiles("*.xlsx").Count()
Else
filecount = 0
lblFileCount.Text = "Files to be processed: " & filecount
End If
End Function
Private Sub Button2_Click(sender As System.Object, e As System.EventArgs) Handles BTN_gencsv.Click
TempFiledir = ("C:\Temp\CustOrders\Input\TempFile.xlsx")
If My.Computer.FileSystem.FileExists(TempFiledir) Then
My.Computer.FileSystem.DeleteFile(TempFiledir)
End If
GetFiles()
End Sub
Sub GetFiles()
'1. Look in the UPLOADED folder for new files
Dim files() As String = Directory.GetFiles("C:\Temp\CustOrders\Uploaded")
Dim di As New DirectoryInfo("C:\Temp\CustOrders\Uploaded")
If files.Count > 0 Then
Dim arrayfi As FileInfo() = di.GetFiles("*.xlsx")
Dim fi As FileInfo
For Each fi In arrayfi
filename = fi.Name
Start(filename)
Next
Else
MsgBox("No files available in directory")
End If
End Sub
Sub Start(filename)
With BTN_gencsv
.BackColor = Color.Red
.ForeColor = Color.White
.Text = "Please wait..."
End With
'2. Get the file that has been uploaded by the customer, copy and rename as TempFile
lblProcessingFile.Visible = True
lblProcessingFile.Text = "Processing file: " & filename
IO.File.Copy("C:\Temp\CustOrders\Uploaded\" & filename, _
"C:\Temp\CustOrders\Input\TempFile.xlsx")
xlApp = New Excel.Application
xlNewApp = New Excel.Application
xlWorkBook = xlApp.Workbooks.Open("C:\Temp\CustOrders\Input\TempFile.xlsx")
xlWorkSheet = xlWorkBook.Worksheets(1)
xlWorkSheet = xlWorkBook.Worksheets("CSV")
xlWorkSheet.Visible = XlSheetVisibility.xlSheetVisible
xlWorkSheet.Unprotect("opencsv")
'3. Copy rows from the CSV worksheet including headers
xlWorkSheet.Range("A1:H100").Copy()
'4. Create new Excel workbook and worksheet so it can have have all rows pasted in
' Then perform all prep work
xlNewWorkBook = xlNewApp.Workbooks.Add(misValue)
xlNewWorkSheet = xlNewWorkBook.Worksheets(1)
xlNewWorkSheet.Select()
' Paste the rows into the new worksheet
On Error Resume Next
xlNewWorkSheet.PasteSpecial(Excel.XlPasteType.xlPasteValues)
xlApp.CutCopyMode = False
' Get current date/time
Dim dt As DateTime = DateTime.Now
Dim dt2 As String = dt
dt2 = dt2.Replace("/", "").Replace(" ", "_").Replace(":", "")
' Select customer number from worksheet
Dim xRng As Excel.Range = CType(xlNewWorkSheet.Cells(2, 5), Excel.Range)
Cust = xRng.Value().ToString()
' If the customer is not found in the spreadsheet lookup it generates "-2146826246" as a value
' This saves the cell as "Not found" to make it look friendly
If Cust.Equals("-2146826246") Then
custFailed += 1
Cust = "Cust_Not_Found_" & custFailed
failedfiles()
Else
CustNo()
End If
releaseObject(xRng)
' This now passes to two error checking subs
End Sub
Sub completeform()
'5. Generate a unique value for Netsuite based on the customer number and current date time
Dim Row As Range
Dim Index As Long
Dim Count As Long
For Index = xlNewWorkSheet.UsedRange.Rows.Count To 1 Step -1
Row = xlNewWorkSheet.UsedRange.Rows(Index)
Count = 0
On Error Resume Next
Count = Row.SpecialCells(XlCellType.xlCellTypeBlanks).Count
If Count = Row.Cells.Count Then Row.Delete(Excel.XlDirection.xlUp)
Next
Dim dt As DateTime = DateTime.Now
Dim dt2 As String = dt
dt2 = dt2.Replace("/", "").Replace(" ", "_").Replace(":", "")
pfile = (Cust + "_" + dt2)
Dim rw As Integer = 1
Do Until xlNewWorkSheet.Cells(rw, 1).Value Is Nothing
rw += 1
Loop
Dim last As String = rw - 1
With xlNewWorkSheet.Range("A1:A100")
.Range(.Cells(2, 1), .Cells(last, 1)).Value = (Cust + "_" + dt2)
End With
'6. Save the workbook with a unique name based on customer number and date/time
xlWorkBook.Saved = True
xlNewWorkBook.SaveAs("C:\Temp\CustOrders\Output\Test_" + pfile + ".csv", Excel.XlFileFormat.xlCSV, misValue, misValue, misValue, misValue, _
Excel.XlSaveAsAccessMode.xlExclusive, misValue, misValue, misValue, misValue, misValue)
'7. Close and release all Excel worksheets and workbooks so they dont remain in memory
xlNewWorkBook.Close(True, misValue, misValue)
xlWorkBook.Saved = True
xlNewWorkBook.Saved = True
releaseObject(xlNewWorkSheet)
releaseObject(xlNewWorkBook)
releaseObject(xlNewApp)
xlWorkBook.Close(False)
xlApp.Quit()
releaseObject(range)
releaseObject(xlWorkSheet)
releaseObject(xlWorkBook)
releaseObject(xlApp)
xlNewApp.Quit()
System.Threading.Thread.Sleep(2000)
'8. Move the processed workbook to the Processed folder ready for a new workbook
IO.File.Move("C:\Temp\CustOrders\Input\TempFile.xlsx", _
"C:\Temp\CustOrders\Processed\Processedfile_" + pfile + ".xlsx")
'9. Move the spreadsheet from Uploaded to OldUploaded ready for a new file
IO.File.Move("C:\Temp\CustOrders\Uploaded\" + filename, _
"C:\Temp\CustOrders\OldUploaded\Uploaded_" + filename)
NoProcessed += 1
lblProcessedCount.Text = "No. Processed..." & NoProcessed
CountFiles()
lblFileCount.Text = "Files to be processed: " & filecount
With BTN_gencsv
.BackColor = SystemColors.Control
.ForeColor = SystemColors.ControlText
.Text = "Generate CSV"
End With
lblProcessingFile.Visible = False
End Sub
Sub CustNo()
Dim c As Range
With xlNewWorkSheet.Range("A1:A100")
c = .Find("#N/A", LookIn:=XlFindLookIn.xlValues)
If Not c Is Nothing Then
custFailed += 1
Cust = "Cust_Not_Found_" & custFailed
MsgBox(Cust)
failedfiles()
Else
quantityBlanks()
End If
End With
End Sub
Sub quantityBlanks()
Dim rw As Integer = 1
Do Until xlNewWorkSheet.Cells(rw, 1).Value Is Nothing
rw += 1
Loop
Dim last As String = rw - 1
Dim rng As Excel.Range
Dim TotalBlanks As Long
TotalBlanks = 0
rng = xlNewWorkSheet.Range(xlNewWorkSheet.Cells(2, 8), xlNewWorkSheet.Cells(last, 8))
On Error Resume Next
TotalBlanks = rng.SpecialCells(XlCellType.xlCellTypeBlanks).Count
If TotalBlanks > 0 Then
Cust = "Quantity_error_"
failedfiles()
Else
referrors()
End If
rng = Nothing
End Sub
Sub referrors()
Dim c As Range
With xlNewWorkSheet.Range("A1:A100")
c = .Find("#REF!", LookIn:=XlFindLookIn.xlValues)
If Not c Is Nothing Then
Cust = "~REF!_errors_"
failedfiles()
Else
completeform()
End If
End With
End Sub
Sub failedfiles()
Dim dt As DateTime = DateTime.Now
Dim dt2 As String = dt
dt2 = dt2.Replace("/", "").Replace(" ", "_").Replace(":", "")
pfile = (Cust + "_" + dt2)
xlWorkBook.Close(False)
xlNewWorkBook.Close(False)
xlNewApp.Quit()
xlApp.Quit()
releaseObject(xlApp)
releaseObject(xlWorkBook)
releaseObject(xlWorkSheet)
releaseObject(xlNewApp)
releaseObject(xlNewWorkBook)
releaseObject(xlNewWorkSheet)
'IO.File.Delete("C:\Temp\CustOrders\Input\Newfile.xlsx")
IO.File.Move("C:\Temp\CustOrders\Input\TempFile.xlsx", _
"C:\Temp\CustOrders\Processed\ProcessedFailedfile_" + pfile + ".xlsx")
IO.File.Move("C:\Temp\CustOrders\Uploaded\" + filename, _
"C:\Temp\CustOrders\Failed\FailedFile_" + pfile + ".xlsx")
With BTN_gencsv
.BackColor = SystemColors.Control
.ForeColor = SystemColors.ControlText
.Text = "Generate CSV"
End With
NoFailed += 1
lblFailed.ForeColor = Color.Red
lblFailed.Text = "No. Failed..." & NoFailed
CountFiles()
lblFileCount.Text = "Files to be processed: " & filecount
lblProcessingFile.Visible = False
End Sub
Private Sub PictureBox1_Click(sender As System.Object, e As System.EventArgs) Handles PictureBox1.Click
CountFiles()
lblFileCount.Text = "Files to be processed: " & filecount
End Sub
End Class