提示用户在关闭表单之前提交更改

Question

I am working on a large .NET 4.0 C# project that spans a few groups. I have been tasked with modifying a form to prompt the user to submit changes. The form that I need to modify has a "Submit Changes", "Ok", "Cancel" buttons. Currently, there are no events triggered by the "Ok" and "Cancel" buttons.

If the user has made any changes, without submitting them, pressing the "Ok" button should generate a MessageBox to guide the user into submitting his/her changes. This is where my problem occurs.

I made the "Ok" button trigger an event buttonOk_Click that checks for changes. The issue here is that since the "Ok" button has been pressed already, I am not sure how to stop the form from closing in order to allow the user to save his/her changes. I cannot modify the code that calls the form since it is part of another group.

How can I stop the form from closing to allow the user to save his changes?

Answer 1

Set the Form DialogResult property to DialogResult.None

 form1.DialogResult = DialogResult.None;

The DialogResult enumeration coupled with the property of the same name on the form and on the buttons is used to control how a modal form is closed and what value is returned to the caller.
For example, pressing a button with its DialogResult property set to OK will force the modal form to exit from the ShowDialog() method with a return value set to DialogResult.OK.

using(Form1 f = new Form1())
{
    if(f.ShowDialog() == DialogResult.OK)
    {
        // Perform post confirmation task on the form data
    }
}

Answer 2

// You may use FormClosing Event of Form

  private void yourForm_FormClosing(object sender, FormClosingEventArgs e)
        {
            if (MessageBox.Show("Want to exit from Application ?",  MessageBoxButtons.YesNo) == DialogResult.Yes)
            {
                Environment.Exit(0);
            }
            else
            {
                // your Code for Changes or anything you want to allow user changes etc.
                e.Cancel = true;

            }

        }

Answer 3

Thanks Bhavin Chhatrola; a slight change if you allow it :)

 private void yourForm_FormClosing(object sender, FormClosingEventArgs e)
 {
     if (MessageBox.Show("Want to exit from Application ?",  MessageBoxButtons.YesNo) == DialogResult.Yes)
     {
         //Environment.Exit(0);
         e.Cancel = false;
     }
     else
     {
         // your Code for Changes or anything you want to allow user changes etc.
         e.Cancel = true;    
     }    
}