public bool UpdateBook(List <int> authorsId, List <int> categoriesId, Book book)
        {
            var authors    = _bookContext.Authors.Where(a => authorsId.Contains(a.Id)).ToList();
            var categories = _bookContext.Categories.Where(c => categoriesId.Contains(c.Id)).ToList();

            var booksAuthorToDelete     = _bookContext.BookAuthors.Where(b => b.BookId == book.Id);
            var booksCategoriesToDelete = _bookContext.BookCategories.Where(b => b.BookId == book.Id);

            _bookContext.RemoveRange(booksAuthorToDelete);
            _bookContext.RemoveRange(booksCategoriesToDelete);

            foreach (var author in authors)
            {
                var bookAuthor = new BookAuthor
                {
                    Author = author,
                    Book   = book
                };
                _bookContext.Add(bookAuthor);
            }

            foreach (var category in categories)
            {
                var bookCategory = new BookCategory
                {
                    Category = category,
                    Book     = book
                };
                _bookContext.Add(bookCategory);
            }

            _bookContext.Update(book);

            return(Save());
        }
 public bool DeleteReviews(List <Review> reviews)
 {
     //var reviewersReview = _reviewContext.Reviews.Where(r => r.Reviewer.Id == reviewerId);
     _reviewContext.RemoveRange(reviews);
     return(Save());
 }