ComboBox选定值为空白

Question

Uses: VS 2012;

I've a combobox attached to a datasource in my form. And things work fine. When I run the form, again everything works fine; I can select an item in the dropdown list and it updates to the datasource as well. My problem comes when I need to deselect/revert what I have selected after I saved or Remove what I have select (basically should go as null for that field value).

Our legacy system was built in Delphi 3 & 5 , and users got a feature of right-clicking on the dropdown list and get a small popup like button named

Blank

which blanks what have been selected. I could not find anything that will do the same what ever user have selected in .NET's combo box.

Answer 1

You can add a new item in dropdown named -Select- ( or something similar name) by using following code:

drp.DataSource = dataSet;
drp.DataBind();
// do it after binding
    drp.Items.Insert(0, new ListItem("-Select-", "NA"));

If you are binding in xaml then on page_load event you can write only this line

 drp.Items.Insert(0, new ListItem("-Select-", "NA"));

Now if user want to deselect choice, he/she will simply select -Select- item.

Answer 2

Whilst thanking all of your Answers and suggestions, I used @V4Vendetta's idea and composed my solution.

Similarly to deleting a record in a datagridview where you click Delete key, I took the same concept and associated my solution with Delete Key.

What I did was created a handler for ComboBox's Keypress Event like:

private void comboBox_KeyPress(object sender, System.Windows.Forms.KeyEventArgs e)
{
    if (e.KeyCode == Keys.Delete)
    {
            (sender as ComboBox).SelectedIndex = -1;    
    }
}

And linked to every ComboBox's available

ComboBox1.KeyDown += new KeyEventHandler(comboBox_KeyPress);
ComboBox2.KeyDown += new KeyEventHandler(comboBox_KeyPress);

Now when user clicks Delete key while the ComboBox selected/active, it gets blank.