如何使用ASP.NET MVC中的实体框架在SQL Server中保存业务模型实体

Question

I have an entity class like this:

namespace Ozhay.Domain.Entities
{
    public class Cart
    {
        private List<CartLine> lineCollection = new List<CartLine>();

        public void AddItem(Product product, int quantity, string size, string color)
        {
            CartLine line = lineCollection
                .Where(p => p.Product.ProductID == product.ProductID)
                .FirstOrDefault();

            if (line == null)
            {
                lineCollection.Add(new CartLine { Product = product, Quantity = quantity, Size = size, Color = color });
            }
            else
            {
                line.Quantity += quantity;
            }
        }

        public void RemoveLine(Product product)
        {
            lineCollection.RemoveAll(l => l.Product.ProductID == product.ProductID);
        }

        public decimal ComputeTotalValue()
        {
            return lineCollection.Sum(e => e.Product.ProductPrice * e.Quantity);
        }

        public void Clear()
        {
            lineCollection.Clear();
        }

        public IEnumerable<CartLine> Lines
        {
            get { return lineCollection; }
        }

        public class CartLine
        {
            [Key]
            public int CartID { get; set; }

            [ForeignKey("Product")]
            public int ProductID { get; set; }
            public Product Product { get; set; }

            public int Quantity { get; set; }
            public string Size { get; set; }
            public string Color { get; set; }

        }
    }
}

I would like to save this into a SQL Server database table but the entity it self is very strange I can save an entity having properties but I have never used to save let say an operational entity, so what would be the right way to save the entity into the database.

Here is the controller:

public class CartController : Controller
{
        private IProductRepository repository;

        public CartController(IProductRepository repo)
        {
            repository = repo;
        }

        public ViewResult Index(Cart cart, string returnUrl)
        {
            return View(new CartIndexViewModel
            {
                ReturnUrl = returnUrl,
                Cart = cart,
            });
        }

        [HttpPost]
        public RedirectToRouteResult AddToCart(Cart cart, int productId, string returnUrl, string SelectedSizeText, string SelectedColorText, int SelectedQuantity)
        {
            Product product = repository.Products
                        .FirstOrDefault(p => p.ProductID == productId);

            if (product != null)
            {
                cart.AddItem(product, SelectedQuantity, SelectedSizeText, SelectedColorText);
            }

            return RedirectToAction("Index", new { returnUrl, SelectedSizeText, SelectedColorText });
        }

        public RedirectToRouteResult RemoveFromCart(Cart cart, int productId, string returnUrl)
        {
            Product product = repository.Products
                .FirstOrDefault(p => p.ProductID == productId);

            if (product != null)
            {
                cart.RemoveLine(product);
            }

            return RedirectToAction("Index", new { returnUrl });
        }

        public PartialViewResult Summary(Cart cart, string returnurl)
        {
            return PartialView(new CartIndexViewModel
            {
                ReturnUrl = returnurl,
                Cart = cart,
            });
        }

        private Cart GetCart()
        {
            Cart cart = (Cart)Session["Cart"];

            if (cart == null)
            {
                cart = new Cart();
                Session["Cart"] = cart;
            }

            return cart;
        }
}

For the moment it is being saved into asp.net session state.

Answer 1

I propose you do not think about EF as about service that can save "business model entities". EF is just data access layer that helps organize your code in ORM (object relation mapping) style. Therefore you should be ready to operate RDBMS concepts (tables, FK, PK) otherwise you will be lost in abstraction leaks.

In classical Magento shop, shopping cart is saved in quote table. How it is related with other tables could be examined there:

https://anna.voelkl.at/wp-content/uploads/2016/12/ce2.1.3.png

So I propose you to start thinking from "RDBMS point of view" even if you use "code first" approach you should use Entities design as a form to write DML ("Create Table ...")