Ndtyjky

I work with c# mvc and entity framework.


I write code for an e shop and i'm trying to write code for the cart.


The cart has a list of cartItems and a cartitem has a product and a quantity variable.


When i want to remove a cartItem from the cart i call the cart.remove(int productid) function i write the appropriate entity framework code to remove it from the database but i also removethe cartitem from the cart class that exists in memory.


I am doing two times the almost the same thing in order to my object to be synchronized with the changes i make to the database. But this does not look very efficient to me.


One time to update the database and one time to update the object that resides in memory.

And i'm doing that almost for every function in my cart class.

here is my classes


public class UserCart
{
private EshopContext db;

    [ForeignKey("user")]

    public string id { get; set; }

    public virtual User.User user { get; set; }



    public virtual List<CartItem> cartItems { get; set; }



    [ForeignKey("voucher")]

    public int voucherId;

    public Voucher voucher { get; set; }



    public double SubTotalCost { get; set; }



    public UserCart(string userId, EshopContext db)

    {

        this.id = userId;

        this.db = db;

        db.UserCarts.Add(this);

        db.SaveChanges();

    }





    public List<CartItem> getCartItems()



    public void add(int productId)





    public void remove(int productId)

    {

        //remove from the database

        CartItem item = db.CartItems.Where(p => p.serialnum == productId && p.cartId == this.id).FirstOrDefault();



        if (item != null)

        {

            if(item.quantity > 1)

            {

                item.quantity -= 1;

                db.SaveChanges();

            }

            else

            {

                db.CartItems.Remove(item);

                db.SaveChanges();

            }

        }



        //remove from the class

        CartItem item2 = cartItems.Where(p => p.serialnum == productId).FirstOrDefault();



        if (item2 != null)

        {

            if (item2.quantity > 1)

            {

                item2.quantity -= 1;

            }

            else

            {

                cartItems.Remove(item2);

            }

        }

    }



    public  double calculateCost()





    public void addVoucher(int voucherId)





    public void removeVoucher()



    public Voucher getVoucher()





    public void clearCart()



}

Whilst @GertArnold's comment is right, it sounds to me like you are approaching this wrong. In my experience, you would update your in-memory object and then save that to the database. Doing it twice is a bad idea.