I am working on a project that runs MySQL queries on DB. I need to feed out the results to a excel sheet that I will be generating on the fly. I had started the code, using msdn tutorials as well as information I found on stackoverflow, however running the application leaves me with
"Object reference not set to an instance of an object."
At this point I just have the basic code started as I wanted to make this work before I started creating the entire spreadsheet in the code.
var excelApp = new Excel.Application();
excelApp.Visible = true;
Excel.Worksheet workSheet = (Excel.Worksheet)excelApp.ActiveSheet;
((Excel.Range)workSheet.Cells[1, 1]).Value = "Print Date:";
If I can provide any more info just ask. I greatly appreciate any information or insight you can provide me with!
I'd say that workSheet is being set to null as excelApp.ActiveSheet doesn't exist yet.
Here's some code that'll create a worksheet object you can use...
var application = new Application();
var workbooks = application.Workbooks;
var workbook = workbooks.Add(XlWBATemplate.xlWBATWorksheet);
var worksheets = (Sheets)workbook.Worksheets;
var worksheet = worksheets[1];
A few things to note when working with Excel:
Release every object with System.Runtime.InteropServices.Marshal.ReleaseComObject(object) when you're finished with it. If you don't, Excel won't exit when you're done.
Don't use double-dot references (i.e., object1.object2.value). If you do you can't release it properly as above.
Indexes always start from 1, not 0 (in my experience anyway).
The reason you get that error is, you have not created any worksheets in the Application.
Try doing this.
Excel.Worksheet newWorksheet;
newWorksheet = (Excel.Worksheet)excelApp.Worksheets.Add();
Related
I have an open instance of Excel which is already connected to via a COM process, which I have changed the value of one of the cells. In C# I can't get a connection to the sheet, but in python i can
Working Python code:
import xlwings as xw
wb = xw.Book('c:/users/me/Desktop/mysheet.xlsx')
sheet = wb.sheets['Sheet1']
print(sheet.range('B1').value) # returns the current value
Non-working C# code:
var xlApp = (Application)System.Runtime.InteropServices.Marshal.GetActiveObject("Excel.Application");
Workbook wb = xlApp.ActiveWorkbook; // returns null
Worksheet excelSheet = wb.ActiveSheet;
string test = excelSheet.Cells[1, 2].Value.ToString();
Is there a way to get C# to connect to this sheet, given it is already open via a COM automation from another software product?
Most of the online discussion around GetActiveObject is to talk to a specific instance of Excel if there are multiple instances running, I have the opposite problem, a single instance of Excel and multiple applications trying to connect to it.
Workbook wb = System.Runtime.InteropServices.Marshal.BindToMoniker(#"c:\users\me\Desktop\mysheet.xlsx") as Workbook;
should get the workbook even if it is already opened in Excel or not.
https://blogs.msdn.microsoft.com/eric_carter/2009/03/12/attaching-to-an-already-running-office-application-from-your-application-using-getactiveobject-or-bindtomoniker/
I'm wanting to import data from an Excel workbook without actually displaying the open workbook.
I could have sworn I had used the following code on a previous project and it had worked:
var excelApp = new Excel.Application { Visible = false };
var workbook = excelApp.Workbooks.Open(filePath);
Unfortunately when the workbook opens it is displayed to the user which is unnecessary for this application.
I'm using Microsoft Excel 15.0 Object Library on this project when previously I think it was version 12 or 13. Maybe this is the problem, or is my memory fading and the code is incorrect?
I know this is old but just in case anybody still needs this answer...
excelApp.Visible = false;
(excelApp being the name of the variable used for the excel application)
I found a problem while using the set_value method. I wrote the simplest possible code to exclude my mistakes.
When I read some cells and then write them back to sheet using set_value while:
any filters are active in xlsx file,
2 or more columns are get/set,
some of the cells are corrupted (they are empty or contain junk like #N/D!). When I disable filtering in worksheet or in program before using set_value, everything works fine. I can't find any info about this specific problem in google, am I doing something really stupid?
Excel.Workbooks workbooks;
Excel.Workbook workbook = null;
Excel.Worksheet sheet = null;
Excel.Application excelApplication;
excelApplication = new Excel.Application();
excelApplication.Visible = false;
workbooks = excelApplication.Workbooks;
workbook = workbooks.OpenXML(file);
sheet = workbook.Sheets[1];
Excel.Range excelRangeR = sheet.UsedRange;
object[,] valueArrayR = (object[,])excelRangeR.get_Value(Excel.XlRangeValueDataType.xlRangeValueDefault);
//if uncomment line below (or manualy disable filters in XLSX file), set_value works fine
//sheet.AutoFilterMode = false;
excelRangeR.set_Value(Excel.XlRangeValueDataType.xlRangeValueDefault, valueArrayR);
workbook.Save();
workbook.Close();
System.Runtime.InteropServices.Marshal.ReleaseComObject(excelRangeR);
System.Runtime.InteropServices.Marshal.ReleaseComObject(sheet);
System.Runtime.InteropServices.Marshal.ReleaseComObject(workbook);
System.Runtime.InteropServices.Marshal.ReleaseComObject(workbooks);
excelApplication.Quit();
System.Runtime.InteropServices.Marshal.ReleaseComObject(excelApplication);
You can leave the filters on, but if there is an active filter on the sheet, that has to be removed before setting the value of the cells. I think what is happening is that when you set the object[,] variable, it's populating the array with all the data in the range, including the rows that are not visible, but when you set the value of the range to the object[,] array, it only overwrites the visible rows. It's either that or vice versa.
Sorry if this code is incorrect. I'm just guessing at the C# Interop syntax. I don't use it all that often.
if (sheet.get_FilterMode()) {
sheet.ShowAllData();
}
Unfortunately there isn't an easy way to save the current value of the worksheet filters, so it would be difficult if you need to be able to restore the filters after the paste operation.
Following is my C# code,where i`m trying to unlock protected sheet by passing password,but it still not unlocking the sheet, I need to add some macro to the sheet .
Code:
const string excelFile = #"c:\temp\VBA\test.xlsm";
var excelApplication = new ExcelInterop.Application { Visible = true };
var targetExcelFile = excelApplication.Workbooks.Open(FileName:excelFile,Password:"12asQOl");
I can`t use "sendKeys" here,please help me on this.
Thanks
One piece of advice when working with VBA: start recording a macro of what you're trying to do then see the generated code.
Looks like you're trying to open a protected file, not unprotect a sheet.
I've found some old code of something like this (it's VB):
Dim WSheet As Worksheet
For Each WSheet In Worksheets
If WSheet.ProtectContents = True Then
WSheet.Unprotect Password:=MyPassword
Else
WSheet.Protect Password:=MyPassword
End If
Next WSheet
In your code you are passing the document password. You are not un-protecting the workbook.
Use the following code to un-protect the workbook:
targetExcelFile.Unprotect(password);
Let me know if you have any issues.
Is there a way to save changes to an excel spreadsheet through the excel interop (in this case I am adding a worksheet to it) without having it prompt the user if they want to overwrite the existing file with the changes. I do not want the user to even see the spreadsheet open in my application so having a message box popping up asking them if they want to overwrite the file seems very out of place and possibly confusing to the user.
I am using the workbook.SaveAs(fileloaction) method.
Here is where I am initializing the COM reference objects for the excel interop.
private Excel.Application app = null;
private Excel.Workbook workbook = null;
public Excel.Workbook Workbook
{
get { return workbook; }
set { workbook = value; }
}
private Excel.Worksheet worksheet = null;
private Excel.Range workSheet_range = null;
Below is the code I am using to close/save the excel file. The workbook.close() method line is the one that is reportedly throwing the unhandled exception.
workbook.Close(true, startForm.excelFileLocation, Missing.Value);
Marshal.ReleaseComObject(app);
app = null;
System.GC.Collect();
Basically, all you need is ExcelApp.DisplayAlerts = False - Here's how I do it, though:
ExcelApp.DisplayAlerts = False
ExcelWorkbook.Close(SaveChanges:=True, Filename:=CurDir & FileToSave)
Hope this helps
Only this code will Require for stop override alert or Template already in use
ExcelApp.DisplayAlerts = False
I know this is an old post, but I wanted to share a way to make this work without causing possible frustration in the future.
First what I do not like about using: ExcelApp.DisplayAlerts = False
Setting this flag will set this property on the excel file, not just in your program. This means that if a user makes changes to the file and closes it (by clicking the X), they will not be prompted to save the file and will cause frustration later. It will also disable any other prompts excel would typically post.
I like checking if the file exists before saving it:
if (File.Exists(SaveAsName))
{
File.Delete(SaveAsName);
}