// delete book
public override Task <Empty> DeleteBook(DeleteBookRequest request, ServerCallContext context)
{
_shelfBookRepository.DeleteBook(request.Shelf, request.Book);
return(Task.FromResult(new Empty()));
}
public IActionResult DeleteBook(long shelfId, long bookId)
{
_shelfBookRepository.DeleteBook(shelfId, bookId);
return(NoContent());
}