Write to file that is open in Excel

Question

Suppose I have a program running that periodically adds information to a .CSV file. Is there a way to write to the file while it is already open in Excel? Obviously the changes wouldn't be noticed until the file was re-opened in Excel, but as it stands right now, I'm catching IOException and just starting a new .csv file if the current one is already open.

Answer 1

It sounds like the file is locked. I doubt you will be able to write to that file if it is open in another process.

Answer 2

Excel seems to open the file in exclusive mode, so the only way I can think of would be to write your changes to a temporary file, and then use FileSystemWatcher to see when the file is closed, and overwrite the file.

Not a very good idea, as you could lose data. The whole reason excel locks the file is so that you don't accidentally overwrite changes made in excel.

Answer 3

As a former (and sort of current) VB Programmer, I can tell you Jared is correct - there is no way to do this directly. You can try to copy the file first, make your edits, then attempt to save the file back to its original location until the locked file becomes free. You should be able to copy that file, even while locked.

Answer 4

What about using Excel's object model and automating the addition of the data into the open spreadsheet? You'd probably need to prompt the user somehow to let them know what was happening.