强制用户仅粘贴有效文件夹目录，并稍后使用C＃在TextBox控件中禁用编辑目录

Question

I am working on Windows Form Application and have created a TextBox control and a Browse button control, so that user can select a folder through Button and show directory in TextBox.

I want to give a freedom to the user to paste a directory path directly into the TextBox. However, at the same, user must provide only a valid directory as a string/text in TextBox.

In addition, I want to disable editing this directory either by keyboard or any other possible way. The user will be able to paste a new valid directory anytime but can't edit it in the TextBox.

Is there any way to do this using C# at runtime?

Thanks.

Answer 1

If you set the textbox to ReadOnly then that stops editing the TextBox .

Then add an event for KeyDown you can capture if Ctrl + V is pressed and then action based on that using the Clipbboard class and if the directory is valid set the TextBox.Text .

private void textBox1_KeyDown(object sender, KeyEventArgs e)
{
  if (e.Modifiers == Keys.Control && e.KeyCode == Keys.V)
  {
    var clipboard = Clipboard.GetText();
    if (Directory.Exists(clipboard))
      textBox1.Text = clipboard;
  }
}

Answer 2

I want to give a freedom to the user to paste a directory path directly into the TextBox. However, at the same, user must provide only a valid directory as a string/text in TextBox.

In addition, I want to disable editing this directory either by keyboard or any other possible way. The user will be able to paste a new valid directory anytime but can't edit it in the TextBox.

Isn't it contradictory ? Why don't you use two text boxes then ? First for user to input/paste, with onchange event catching that calls a method that checks the directory's path is correct. If it is, the method copies it to the second text box, not editable, that is also linked to your directory browser.

Answer 3

You could handle the TextChanged event and check to see if the folder is valid and accessible there; if it's not, undo their change. This might not be practical if they can edit the textbox text, as it'll check to see if the folder exists after every keystroke and so typing anything new will be impossible. This might be how you want it to behave however!

To do the checking if the path is valid, I'd use Path.GetFullPath - pass it your textbox text and it'll throw an exception if the path doesn't exist/isn't valid/you don't have permission to access it.

If this feels a bit messy to you, instead of giving them the ability to edit the textbox, you could have a button that sets the text from the clipboard using Clipboard.GetText() and then performs your checks.

Answer 4

Thanks all for suggestions and answers. Here is something that I did and worked like a charm for me. I hope, this will help later for someone if face the same problem.

It is the modified version of the original code posted here by LukeHennerley. Thanks LukeHennerley for that.

private void txtBoxTargetDir_KeyDown(object sender, KeyEventArgs e)
    {
        if (e.Modifiers == Keys.Control && e.KeyCode == Keys.V)
        {
            var clipboard = Clipboard.GetText();
            if (Directory.Exists(clipboard))
            {
                txtBoxTargetDir.Clear();
                txtBoxTargetDir.Text = clipboard;
                txtBoxTargetDir.ReadOnly = true;
            }
            else
            {
                txtBoxTargetDir.Clear();
                txtBoxTargetDir.Text = "It's not a valid directory. Please provide a valid directory.";
            }
        }
    }

You will have to add this event in Form.Designer.cs first.