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c#filteropenfiledialogsavefiledialog

OpenFileDialog & SaveFileDialog Pop-up search with filter in C#

I have openFileDialog and saveFileDialog with filter (only .dvbcfg extention):

SaveFileDialog saveFileDialog = new SaveFileDialog();
saveFileDialog.Filter = "DVB Configuration File (*.dvbcfg)|*.dvbcfg";
saveFileDialog.DefaultExt = "dvbcfg";
saveFileDialog.AddExtension = true;

It works properly, but when I'm trying to type filename manually it shows files with any extentions w/o filtering and opens/saves them (first - open file, second - save file): ScreenShot

How to show only files that matches saveFileDialog.Filter?

P.S. I have overwrite function in saveFileDialog.

UPD I have another option - throw an exception when user selected wrong filetype, but I have no idea how to get only file extention from saveFileDialog.FileName string.

Solution

  • At a certain point, you have to "trust" your users. You can steer them towards good ways of working with your program, but at a certain point, you have to recognise that you've put enough simple barriers in their way to prevent accidental misuse1 but you're unlikely to be able to create enough barriers (in these dialogs) to prevent malicious misuse.

    The problem is that using wrong file may cause damage to expensive equipment (DVB-3030 Digital Modulator in this case) even if I'm using try/catch to get variables from files (they need to be integers, in try segment I have Convert.ToInteger32) and variable ranges in if/else checks (for example Frequency range should be 10MHz - 90 MHz with 100Hz step). Since program will be used by students, they can purposely try to break it.

    And nothing in your current question (or sought answer) would prevent someone from renaming any arbitrary file to have a .dvbcfg extension.

    At this point, you "trust" that the user has given you the filename they wish to use. What you need to do next is to validate the contents of the file. If it has a .dvbcfg extension but isn't actually a valid DVB config file, you need to reject it. If it doesn't have a .dvbcfg extension (hey, maybe they're working with an old file system that only allows 8.3 file names :-)) but turns out to have valid content, why be churlish and reject that file?

    I would recommend more than just wrapping ToInteger32 calls in try/catch. Go through the file. Ensure it contains exactly what it should and nothing else. Read each parameter value and probably use TryParse on those. Because your code now "expects" to receive invalid inputs. Then validate ranges, etc.

    1Which I'd say you've already got.