public RequestResult EditLiterature(LiteratureViewModel lit)
        {
            foreach (var book in lit.Books.Where(book => DataProvider.LibraryBooks.Filter(p=>p.BookNumber==book.BookNumber && p.Id!=book.RowId).Any()))
            {
                return new RequestResult(1, "Книга с  номером - " + book.BookNumber + "- уже существует");
            }
            var literature = DataProvider.LibraryLiteratures.FirstOrDefault(p => p.Id == lit.Id);

            literature = literature ?? new Library_Literature();

            literature.FullName = lit.FullName;
            literature.ShortName = lit.ShortName;
            literature.Year = lit.Year;
            literature.PublishingHouse = lit.PublishingHouse;
            literature.MainAuthor = lit.MainAuthor;
            literature.AdditionalAuthors = lit.AdditionalAuthors;
            literature.Desqription = lit.Desqription;

               try
            {
                if (literature.Id==0)
                    DataProvider.LibraryLiteratures.Add(literature);

                DataProvider.Save();

                foreach (var book in lit.Books)
                {
                    var editBook = literature.Library_Book.FirstOrDefault(p => p.Id == book.RowId);

                    if (editBook == null)
                    {
                        DataProvider.LibraryBooks.Add(new Library_Book()
                        {
                            BookNumber = book.BookNumber,
                            Library_Literature = literature
                        });

                    }
                    else
                        editBook.BookNumber = book.BookNumber;
                    DataProvider.Save();
                }

                return RequestResult.Ok;
            }
            catch (Exception)
            {
              return new RequestResult(1,"ЗАполните все данные формы");
            }
        }
 public ActionResult Save(LiteratureViewModel model)
 {
     var updateResult = _literatureService.EditLiterature(model);
     return Json(updateResult.Equals(RequestResult.Ok) ? new { type = "success", message = "Литература успешно сохранена" } : new { type = "error", message = updateResult.RequestMessage });
 }