Question

I have a C# .NET 3.5 program that uses an OpenFileDialog to retrieve a file for importing. It has two filters (*Domain*.* and *.*) and the *Domain*.* is chosen as the FilterIndex. I’m seeing a case of a disappearing file from the filters when it is modified within the OpenFileDialog.

Here are the steps the user will take to reproduce the problem:

1. In the program, open the OpenFileDialog. Ensure that the filter is set to *Domain*.*.
2. Find a file in the directory that matches the filter and change the file name so that it no longer matches the filter. Note: the file will disappear.
3. Change the filter to show all files *.*. Note: the file is not listed even though you’re supposedly showing *.*.

At this point, you can open the folder in Windows Explorer and see that the file with the changed name exists. However, in the OpenFileDialog, it is no longer visible regardless of the filter that is used. The only way to see that file again is to close the OpenFileDialog and then reopen it.

Here is my code that creates the OpenFileDialog.

using(OpenFileDialog domainFileDialog = new OpenFileDialog())
{
    domainFileDialog.CheckFileExists = true;
    domainFileDialog.CheckPathExists = true;
    domainFileDialog.Filter = "Domain Files (*Domain*.*)|*Domain*.*|All files (*.*)|*.*";
    domainFileDialog.FilterIndex = 1;
    domainFileDialog.Multiselect = false;
    domainFileDialog.RestoreDirectory = true;
    domainFileDialog.ShowReadOnly = true;
    domainFileDialog.SupportMultiDottedExtensions = true;
    domainFileDialog.Title = "Choose the Domain File to Import...";
    domainFileDialog.ValidateNames = true;

    \\ Perform Import functionality...
}

It seems as though when you open the OpenFileDialog and modify an existing file that matches the more restrictive filter so that it no longer matches the filter, the file disappears from visibility even when all files *.* are displayed.

Since I have no idea why this is happening, (and I’m open for suggestions as to how to fix it) is there any way to restrict a user from creating or modifying any of the files in the OpenFileDialog in hopes of preventing this problem?

Answer 1

First, I’d suggest you consider whether it is worth caring that the user might do this. If the FOD does this, every windows application has this feature, but you don’t hear users complaining about it. So is it really an issue that needs fixing?

It wouldn’t surprise me if the problem’s related to the filter being for more than just a file extension – it’s rather unconventional to do this. Maybe try it with an extension only and see if this is the cause.

Have you tried pressing F5 to refresh its cached data? I don’t know if this would work in a FOD as it does in an explorer window, but it might be interesting to give it a try.

Having said all that, it would be trivial to filter keypresses (F2) and mouse clicks (right button) )(with some forms you could derive off it, or you could drop in a MessageFilter) to make it impossible for a user to access any UI that allows them to rename a file in the FOD. It would piss me off, as a user, if you broke the FOD in this waym though – much more than a renamed file “disappearing” under rare circumstances, anyway.