BooksSample.Program.UpdateAsync C# (CSharp) Метод

        private static async Task UpdateAsync(BooksContext context, Book book, string user)
        {
            try
            {
                WriteLine($"{user}: updating id {book.BookId}, timestamp {book.TimeStamp.StringOutput()}");
                ShowChanges(book.BookId, context.Entry(book));

                int records = await context.SaveChangesAsync();
                WriteLine($"{user}: updated {book.TimeStamp.StringOutput()}");
                WriteLine($"{user}: {records} record(s) updated while updating {book.Title}");
            }
            catch (DbUpdateConcurrencyException ex)
            { 
                WriteLine($"{user} update failed with {book.Title}");
                WriteLine($"{user} error: {ex.Message}");
                foreach (var entry in ex.Entries)
                {
                    Book b = entry.Entity as Book;

                    WriteLine($"{b.Title} {b.TimeStamp.StringOutput()}");
                    ShowChanges(book.BookId, context.Entry(book));
                }
            }            
        }