public void SaveAuthor(Author author)
 {
     if (author.Id == 0)
         context.Authors.Add(author);
     else
         context.Entry(author).State = EntityState.Modified;
     context.SaveChanges();
 }
 public void DeleteAuthor(Author author)
 {
     context.Authors.Remove(author);
     context.SaveChanges();
 }
 public void AddAuthor(Author author)
 {
     context.Authors.Add(author);
     context.SaveChanges();
 }