c# AcceptButton and validation

Question

Hi I have a form which contains of several textboxes and two buttons Cancel and Ok. These buttons are assigned to accept and cancel buttons properties in form. The problem is that I have to validate texts entered in all textboxes.

I want to do that if user click Ok button(which is acceptButton). So I wrote a function which is reponsible for validation and I fire this function if user click Ok button. The problem is that I can't stop form from closing even if validation function return false. It happens because of the fact that I assigned acceptbutto property to my Ok button. Is there any way to prevent form from closing if validation fails without removing acceptbutton properties ??

Answer 1

Don't set the AcceptButton property in your Form and remove the DialogResult property from your button (set it to DialogResult.None instead).

You can set the DialogResult property of your form in your validation code instead.

 if (allFieldsValidated) {
     DialogResult = DialogResult.OK;
 }

Answer 2

One way could be to apply the validation in OnFormClosing event and cancel the action based upon validation result.

--EDIT--

private void Form1_FormClosing(object sender, FormClosingEventArgs e)
{
    if (this.DialogResult == DialogResult.OK)
    {
        if (!IsValid())
        {
            Info("Invalid data");
            e.Cancel = true;
        }
        else
        {
            Info("Valid data found, closing dialog");
        }
    }
    else if (this.DialogResult == DialogResult.Cancel)
    {
        Info("Just cancelling!");
    }
}

And you may call this.Close(); on Cancel/Ok events.

Alternatively, in your OK button implementation you can change the DialogResult of the button and set it to None;

acceptButton.DialogResult = DialogResult.None;

Answer 3

In the Ok button click handler change DialogResult to DialogResult.None when validation fails