Model多增加兩隻class在C#專案

public class ShoppingCart
{
    public int Id { get; set; }
    public Guid SessionId { get; set; }
    public DateTime CreatedOn { get; set; }
    public List<CartLineItem> Items { get; set; } = new List<CartLineItem>();
}

public class CartLineItem
{
    public int Id { get; set; }
    public int ProductId { get; set; }
    public int Quantity { get; set; }
}

資料庫上下文添加ShoppingCart的Entity

public class StoreContext : DbContext
    {
        public StoreContext(DbContextOptions<StoreContext> options) : base(options) { }

        public DbSet<Product> Products { get; set; }
        public DbSet<ShoppingCart> ShoppingCart { get; set; }
    }

新增好Cart控制器

[Route("api/[controller]")]
    [ApiController]
    public class CartController : ControllerBase
    {
        private readonly StoreContext dbContext;

        public CartController(StoreContext dbContext)
        {
            this.dbContext = dbContext;
        }

        [HttpPost]
        public IActionResult AddItem(AddItemCommand command)
        {
                       
            var cart = new ShoppingCart { SessionId = Guid.NewGuid(), CreatedOn = DateTime.Now };
            cart.Items.Add(new CartLineItem { ProductId = command.ProductId, Quantity = 1 });

            dbContext.ShoppingCart.Add(cart);
            dbContext.SaveChanges();

            return Ok();
        }

    }

    public class AddItemCommand
    {
        public int ProductId { get; set; }
    }