public IActionResult Confirm(int?id)
{
if (id == null)
{
return(NotFound());
}
var loan = _loan.GetById(id.Value);
if (loan == null)
{
return(NotFound());
}
if (!loan.State)
{
loan.State = true;
_loan.Update(loan);
}
return(RedirectToAction(nameof(CheckReturnBook)));
}