protected void ValidateISBN(object source, ServerValidateEventArgs args)
{
if (this.txtISBN.Text != isbn_book)
{
this.cvISBN.ErrorMessage = "";
if (args.Value.Length == 13)
{
try
{
long.Parse(args.Value);
if (!Crud.CheckRegisteredISBN(this.txtISBN.Text))
{
args.IsValid = true;
}
else
{
this.cvISBN.ErrorMessage = "This ISBN is already registered.";
args.IsValid = false;
}
}
catch (Exception)
{
this.cvISBN.ErrorMessage = "Invalid ISBN. Only numbers.";
args.IsValid = false;
}
}
else
{
this.cvISBN.ErrorMessage = "ISBN must have 13 digits.";
args.IsValid = false;
}
}
}
