public ActionResult Add(BookModel model)
 {
     if (ModelState.IsValid)
     {
         var isbn = ISBNFilter.Filter(model.ISBN);
         new BookRepository().Insert(new Book
         {
             ISBN = isbn,
             Title = model.Title,
             AuthorId = model.AuthorId,
         });
         return RedirectToAction("Index", "Home", new { message = (int)BooksListSuccessMessage.BookAddedSuccesfully });
     }
     model.IsEditMode = false;
     model.Authors = GetAuthorsList();
     return View("Edit", model);
 }
 public ActionResult Edit(BookModel model)
 {
     if (ModelState.IsValid)
     {
         var isbn = ISBNFilter.Filter(model.ISBN);
         new BookRepository().Save(new Book
         {
             Id = model.Id,
             ISBN = isbn,
             Title = model.Title,
             AuthorId = model.AuthorId
         });
         return RedirectToAction("Index", "Home", new { message = (int)BooksListSuccessMessage.BookEditedSuccesfully });
     }
     model.IsEditMode = true;
     model.Authors = GetAuthorsList();
     return View(model);
 }