public async Task <OrderModel> Handle(SubmitOrderCommand request, CancellationToken cancellationToken)
{
var cart = await _dbContext.Carts
.Include(x => x.Books)
.SingleOrDefaultAsync(
x => x.Id == request.CartId, cancellationToken);
if (cart == null)
{
throw NotFoundError.CreateForResource(nameof(Cart), request.CartId).ToException();
}
var order = new Order(cart, request.PhoneNumber);
await _dbContext.AddAsync(order, cancellationToken);
_dbContext.Remove(cart);
await _dbContext.SaveChangesAsync(cancellationToken);
return(_mapper.Map <OrderModel>(order));
}