Question

I have two textboxes. I need to validate them before taking any other action.

private ErrorProvider _errorProviderEmail = new ErrorProvider();
private ErrorProvider _errorProviderPass = new ErrorProvider();
public FormLogin()
{
  InitializeComponent();

  textBoxEmail.Validating += TextBoxEmailValidating;
  textBoxPass.Validating += TextBoxPassValidating;

  textBoxEmail.Validated += TextBoxEmailValidated;
  textBoxPass.Validated += TextBoxPassValidated;

  textBoxEmail.Text = "";
  textBoxPass.Text = "";
}

void TextBoxPassValidated(object sender, EventArgs e)
{
  _errorProviderPass.SetError(textBoxPass, "");
}

void TextBoxEmailValidated(object sender, EventArgs e)
{
  _errorProviderEmail.SetError(textBoxEmail, "");
}

void TextBoxPassValidating(object sender, System.ComponentModel.CancelEventArgs e)
{
  if (!string.IsNullOrEmpty(textBoxPass.Text)) return;
  e.Cancel = true;
  _errorProviderPass.SetError(textBoxPass,"Password is required!");
}

void TextBoxEmailValidating(object sender, System.ComponentModel.CancelEventArgs e)
{
  if (!string.IsNullOrEmpty(textBoxEmail.Text)) return;
  e.Cancel = true;
  _errorProviderEmail.SetError(textBoxEmail, "Email address is required!");
}

The problem is that only validating event for textBoxEmail is triggered, what could be wrong here, and why the validating event for textBoxPass never fires?

Answer 1

The individual TextBox controls only validate when they lose their focus.

Try calling the form’s ValidateChildren() function to force each control to call their validation handlers:

private void button1_Click(object sender, EventArgs e) {
  if (this.ValidateChildren()) {
    this.Close();
  }
}

Also, you only need one ErrrorProvider component.