Clearing all data on tab page when clicking No Button

Question

in my application im submitting a data to the db on a tabControls page(page:tabPage2) and i want when hitting the submit button first saving data to db(im achieving this) the a question will ask anything will be done? if the user hit the no button all fields on tabpage2 will reset. so i wrote a script like below but it is not clearing fields.

        if (dr == DialogResult.Yes)
        {
            for (int i = 0; i < this.tabControl1.Controls.Count; i++)
            {

                if (this.tabControl1.SelectedTab == tabPage2)
                {
                    if (tabPage2.Controls[i] is TextBox)
                    {
                        tabPage2.Controls[i].Text = "";
                    }

                    if (tabPage2.Controls[i] is ComboBox)
                    {
                        tabPage2.Controls[i].Text = "";
                    }

                    if (tabPage2.Controls[i] is PictureBox)
                    {
                        tabPage2.Controls[i].Text = "";
                    }

                    if (tabPage2.Controls[i] is RadioButton)
                    {
                        tabPage2.Controls[i].Text = "";
                    }

                }


            }

        }

Answer 1

You are itering over the collection of TabControl child controls, not actual TabPage's.

Change your code to this instead:

if (dr == DialogResult.Yes && this.tabControl1.SelectedTab == tabPage2)
{
    foreach (var ctrl in tabPage2.Controls)
    {
        if (ctrl is TextBox || ctrl is ComboBox || ctrl is PictureBox || ctrl is RadioButton)
        {
            ctrl.Text = "";
        }
    }
}

I should say though than setting the Text property to "" for controls other than TextBox feels rather wrong to me. As you'll find out, this won't work for combos, images and radio buttons.

Also if you have controls nested into panels or the like they won't be cleared. Containers have their own nested collection of controls, which in turn can also be containers, and so on and on.

IMHO it would be far better for you to explicitely reset form controls one by one rather than trying to find them dynamically on your form. This way you'll be free to move your controls around at design time without ever worrying about breaking the resetting logic.

Additional suggestion: you can also attach your controls at design time to an instance of your own IExtenderProvider component which will take care of resetting controls appropriately based on their type.

Answer 2

If you control the class for the page layout within the specific tab page you want to clear, it's probably best to create a public or internal method in that class (such as Clear()) which can access each of its member controls and clear them directly. That's the easiest approach, and it should usually apply.

If you instead need it to handle a page with an unknown structure, you might need an approach like:

private void ClearControls(Control parentControl)
{
    foreach (Control ctrl in parentControl.Controls)
    {
        TextBox ctrlText;
        ComboBox ctrlCombo;
        PictureBox ctrlPicture;
        RadioButton ctrlRadio;

        // Pay careful attention to the parentheses...
        if ((ctrlText = ctrl as TextBox) != null)
        {
            ctrlText.Text = string.Empty;
        }
        else if ((ctrlCombo = ctrl as ComboBox) != null)
        {
            ctrlCombo.SelectedIndex = -1;
        }
        else if ((ctrlPicture = ctrl as PictureBox) != null)
        {
            // Logic to clear a PictureBox called ctrlPicture
        }
        else if ((ctrlRadio = ctrl as RadioBox) != null)
        {
            // Logic to clear a RadioButton called ctrlRadio
        }
        else if (ctrl.Controls.Count > 0)
        {
            ClearControls(ctrl); // Recursively clear contained controls.
        }
    }
}

With a call to start it off from the original handler:

if (dr == DialogResult.Yes)
    ClearControls(this.tabControl1);