I am trying to save an excel file that was created and written to via a C# application using the Excel Interop. I have looked all over this site as others to find a code that properly works and I have yet to find one. My excel interop funciton uses a workbook, worksheet, app, and workshee_range object. Does anyone have any suggestions. The easier the solution the better. I’m a beginner to intermediate level C# programmer and an advanced solution will likely be out of my scope of knowledge. The unhandled exception I am getting when trying to disconnect from the excel interop after saving and then closting the excel file says ‘Object reference not set to an instance of an object.’
here is the code I am using to do the aforementioned process:
workbook.SaveAs(startForm.excelFileLocation);
workbook.Close();
app.Quit();
Marshal.ReleaseComObject(workSheet_range);
Marshal.ReleaseComObject(worksheet);
Marshal.ReleaseComObject(workbook);
Marshal.ReleaseComObject(app);
app = null;
workbook = null;
worksheet = null;
workSheet_range = null;
Here is the full bit of code:
class CreateExcelDoc
{
string newFormString = trialReportForm.newFormString;
string fileString=trialReportForm.fileString;
int sheetCount;
string trialString = trialReportForm.trialString;
string dateString = trialReportForm.dateString;
string saveString = trialReportForm.saveSting;
System.Windows.Forms.Timer excelTimer = new System.Windows.Forms.Timer();
private Excel.Application app = null;
private Excel.Workbook workbook = null;
private Excel.Worksheet worksheet = null;
private Excel.Range workSheet_range = null;
public CreateExcelDoc()
{
createDoc();
}
public void createDoc()
{
try
{
app = new Excel.Application();
//app.Visible = false;
if (startForm.exportOwnerString == "Yes")
{
app.Visible = true;
startForm.exportOwnerString = " ";
}
else
{
app.Visible = false;
}
if (startForm.excelActionFlag=="addNewTrialReport")
{
workbook = (Excel.Workbook) app.Workbooks.Add(1);
//workbook.SaveAs(newFileForm.desktopPath + "\\" + "OB "+trialReportForm.otrClubNameString+" - "+trialReportForm.otrDateString);
worksheet = (Excel.Worksheet)workbook.Worksheets[1];
//fileNameString = newFileForm.desktopPath + "\\OB " + trialReportForm.otrClubNameString + " " + trialReportForm.otrDateString;
workbook.Worksheets[1].Name = trialReportForm.trialReportDate+" Trial "+trialReportForm.trialReportTrialNumber;
}
else if (startForm.excelActionFlag == "ownerContacts")
{
workbook = (Excel.Workbook)app.Workbooks.Add(1);
worksheet = (Excel.Worksheet)workbook.Worksheets[1];
workbook.Worksheets[1].Name = "Owner Contacts";
}
else if (startForm.excelActionFlag == "newExcelResults")
{
string testFile = Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData) + "\\test";
workbook = (Excel.Workbook)app.Workbooks.Add(1);
worksheet = (Excel.Worksheet)workbook.Worksheets[1];
workbook.Worksheets[1].Name = "Event 1 Results";
//workbook.SaveAs(testFile, Missing.Value, Missing.Value, Missing.Value, false);
//workbook.SaveAs(Environment.GetFolderPath(Environment.SpecialFolder.Desktop)+"\\Results", Missing.Value, Missing.Value, Missing.Value, false);
//workbook.SaveAs(startForm.excelFileLocation, Missing.Value, Missing.Value, Missing.Value, false);
//fileNameString = registrationForm.regFileLocation + "\\OB " + registrationForm.regClubName + " " + registrationForm.regDateString;
}
else if (dogForm.dogRegistrationExcel == "Yes")
{
workbook = (Excel.Workbook)app.Workbooks.Add(1);
workbook.SaveAs(dogForm.filePath, Missing.Value, Missing.Value, Missing.Value, false);
}
else if (newFormString == "No")
{
//workbook = app.Workbooks.Open(fileString, Missing.Value, false, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, true, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value);
// workbook.Close(true,fileString,Missing.Value);
workbook = (Excel.Workbook)app.Workbooks.Open(fileString, Missing.Value, false, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, true, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value);
}
if (newFormString=="Yes"®istrationForm.formString=="OTR")
{
//string sheetName = "Trial Report - " + dateString + " " + trialString;
worksheet = (Excel.Worksheet)workbook.Worksheets[1];
workbook.Worksheets[1].Name =trialReportForm.otrDateString+" Trial " + trialReportForm.otrTrialString;
//workbook.Worksheets[1].Name = "Trial Report - " + dateString + " " + trialString;
//workbook.Worksheets[1].Name = "Hello";
//Excel.Name name1 = worksheet.Names.Add("Trial Report - " + dateString + " " + trialString, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value);
//worksheet.Name = "Trial Report - " + dateString + " " + trialString;
}
else if (newFormString == "Yes" & registrationForm.formString == "Registration")
{
//string sheetName = "Trial Report - " + dateString + " " + trialString;
worksheet = (Excel.Worksheet)workbook.Worksheets[1];
workbook.Worksheets[1].Name = "Results: "+registrationForm.selectedEvent;
//workbook.Worksheets[1].Name = "Trial Report - " + dateString + " " + trialString;
//workbook.Worksheets[1].Name = "Hello";
//Excel.Name name1 = worksheet.Names.Add("Trial Report - " + dateString + " " + trialString, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value);
//worksheet.Name = "Trial Report - " + dateString + " " + trialString;
}
else if (startForm.excelActionFlag == "addExistingTrialReport")
{
workbook = (Excel.Workbook)app.Workbooks.Open(startForm.excelFileLocation, Missing.Value, false, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, true, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value);
sheetCount = workbook.Worksheets.Count;
int sheetCountPlusONe=sheetCount+1;
worksheet = (Excel.Worksheet)workbook.Worksheets.Add(Missing.Value,workbook.Worksheets[sheetCount],Missing.Value,Missing.Value);
workbook.Worksheets[sheetCountPlusONe].Name = trialReportForm.trialReportDate + " Trial " + trialReportForm.trialReportTrialNumber;
//worksheet.Move(Missing.Value, workbook.Worksheets[sheetCount]);
}
else if (startForm.excelActionFlag == "existingExcelResults")
{
workbook = (Excel.Workbook)app.Workbooks.Open(startForm.excelFileLocation, Missing.Value, false, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, true, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value);
sheetCount = workbook.Worksheets.Count;
int sheetCountPlusONe = sheetCount + 1;
worksheet = (Excel.Worksheet)workbook.Worksheets.Add(Missing.Value, workbook.Worksheets[sheetCount], Missing.Value, Missing.Value);
workbook.Worksheets[sheetCountPlusONe].Name = "Event " + sheetCountPlusONe.ToString() + " Results";
//worksheet.Move(Missing.Value, workbook.Worksheets[sheetCount]);
}
else if (dogForm.dogRegistrationExcel == "Yes")
{
worksheet = (Excel.Worksheet)workbook.Worksheets[1];
workbook.Worksheets[1].Name = dogForm.dogUKCNumber;
}
}
catch (Exception e)
{
Console.Write("Error");
}
/* if (trialReportForm.saveMe=="Yes")
{
workbook.Save();
workbook.Close();
}
*/
}
public void createHeaders(int row, int col, string htext, string cell1,
string cell2, int mergeColumns, string b, bool font, int size, string
fcolor)
{
worksheet.Cells[row, col] = htext;
workSheet_range = worksheet.get_Range(cell1, cell2);
workSheet_range.Merge(mergeColumns);
switch (b)
{
case "BLUE":
workSheet_range.Interior.Color = System.Drawing.Color.Red.ToArgb();
break;
case "GAINSBORO":
workSheet_range.Interior.Color =
System.Drawing.Color.Gainsboro.ToArgb();
break;
//case "Turquoise":
// workSheet_range.Interior.Color =
//System.Drawing.Color.Turquoise.ToArgb();
//break;
case "PeachPuff":
workSheet_range.Interior.Color =
System.Drawing.Color.PeachPuff.ToArgb();
break;
default:
// workSheet_range.Interior.Color = System.Drawing.Color..ToArgb();
break;
}
//workSheet_range.Borders.Color = System.Drawing.Color.Black.ToArgb();
//workSheet_range.Borders = null;
workSheet_range.Font.Bold = font;
workSheet_range.ColumnWidth = size;
//workSheet_range.HorizontalAlignment = ContentAlignment.BottomCenter;
if (startForm.excelActionFlag == "existingExcelResults" | startForm.excelActionFlag=="newExcelResults")
{
workSheet_range.HorizontalAlignment = Microsoft.Office.Interop.Excel.XlHAlign.xlHAlignCenter;
}
//workSheet_range.Cells.HorizontalAlignment = ContentAlignment.MiddleCenter;
workSheet_range.Font.Color = System.Drawing.Color.FloralWhite.ToArgb();
}
public void addData(int row, int col, string data,
string cell1, string cell2, string format)
{
worksheet.Cells[row, col] = data;
workSheet_range = worksheet.get_Range(cell1, cell2);
//workSheet_range.Borders.Color = System.Drawing.Color.Black.ToArgb();
workSheet_range.NumberFormat = format;
workSheet_range.HorizontalAlignment = Microsoft.Office.Interop.Excel.XlHAlign.xlHAlignLeft;
excelTimer.Tick += new EventHandler(excelTimer_Tick);
excelTimer.Interval = 6000;
excelTimer.Start();
}
void excelTimer_Tick(object sender, EventArgs e)
{
if (startForm.excelActionFlag != "ownerContacts")
{
if (startForm.excelActionFlag == "existingExcelResults" | startForm.excelActionFlag == "newExcelResults")
{
/* Excel.Range sortRange;
sortRange = worksheet.get_Range("A14", "K32");
Excel.Range scoreColumn;
scoreColumn = worksheet.get_Range("C14", "C32");
sortRange.Sort(scoreColumn, Excel.XlSortOrder.xlDescending);*/
Excel.Range valueRange;
Excel.Range placeRange;
placeRange = worksheet.get_Range("A14", "A" + (14 + (registrationForm.numberofCompetitors - 1)).ToString());
valueRange = worksheet.get_Range("A14", "K"+(14+(registrationForm.numberofCompetitors-1)).ToString());
valueRange.Sort(valueRange.Columns[3, Type.Missing], Excel.XlSortOrder.xlDescending, Type.Missing, Type.Missing, Excel.XlSortOrder.xlAscending, Type.Missing, Excel.XlSortOrder.xlAscending, Excel.XlYesNoGuess.xlGuess, Type.Missing, Type.Missing, Excel.XlSortOrientation.xlSortColumns, Excel.XlSortMethod.xlPinYin, Excel.XlSortDataOption.xlSortNormal, Excel.XlSortDataOption.xlSortNormal, Excel.XlSortDataOption.xlSortNormal);
placeRange.Sort(placeRange.Columns[1, Type.Missing], Excel.XlSortOrder.xlAscending, Type.Missing, Type.Missing, Excel.XlSortOrder.xlAscending, Type.Missing, Excel.XlSortOrder.xlAscending, Excel.XlYesNoGuess.xlGuess, Type.Missing, Type.Missing, Excel.XlSortOrientation.xlSortColumns, Excel.XlSortMethod.xlPinYin, Excel.XlSortDataOption.xlSortNormal, Excel.XlSortDataOption.xlSortNormal, Excel.XlSortDataOption.xlSortNormal);
}
// workbook.Close(true, Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData) + "\\Results.xls", Missing.Value);
/*
GC.Collect();
GC.WaitForPendingFinalizers();
GC.Collect();
GC.WaitForPendingFinalizers();
Marshal.FinalReleaseComObject(workSheet_range);
Marshal.FinalReleaseComObject(worksheet);
workbook.Close(Type.Missing, Type.Missing, Type.Missing);
Marshal.FinalReleaseComObject(workbook);
app.Quit();
Marshal.FinalReleaseComObject(app);
*/
//workbook.Close(true, startForm.excelFileLocation, Missing.Value);
workbook.SaveAs(startForm.excelFileLocation);
workbook.Close();
//app.Application.Quit();
app.Quit();
Marshal.ReleaseComObject(workSheet_range);
Marshal.ReleaseComObject(worksheet);
Marshal.ReleaseComObject(workbook);
Marshal.ReleaseComObject(app);
app = null;
workbook = null;
worksheet = null;
workSheet_range = null;
//Application.Exit();
/* workSheet_range = null;
worksheet = null;
workbook = null;
app = null;*/
//Thread.Sleep(5000);
// File.Move(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData) + "\\Results.xls", startForm.excelFileLocation);
}
This means that when
excelTimer_Tickis executed, the value ofworkbookisnull(startFormcan’t be null, because otherwise you would have the error onif (startForm.excelActionFlag != "ownerContacts")).I’d put a breakpoint on that line and check in the Watch window (or QuickWatch) whether it’s null or not.
To see why it’s null, you can refactor your
workbookfield into a property and put the breakpoint in the setter to see when it’s set to null (or whetherexcelTimer_Tickis called before the field is set).