The specified type member 'Product' is not supported in LINQ to Entities

Question

I'm getting the error 'Product' is not supported in LINQ to Entities whilst using cartItems.Product.UnitCost when trying to get the total of the basket.

public decimal GetTotal()
    {
        //Multiply price by count of item to get price for each item in cart and them sum all prices up
        decimal? total = (from cartItems in db.ShoppingBaskets where cartItems.BasketID == ShoppingCartID select (int?)cartItems.BasketQuantity * cartItems.Product.UnitCost).Sum();

        return total ?? decimal.Zero;
    }

I then tried splitting the query up to see if this would fix the problem

int? quantity = (from cartItems in db.ShoppingBaskets where cartItems.BasketID == ShoppingCartID select (int?)cartItems.BasketQuantity).Sum();

decimal? price = (from cartItems in db.ShoppingBaskets where cartItems.BasketID == ShoppingCartID select cartItems.Product.UnitCost).Sum();

I get the same problem with the second separate query with 'Product'.

Product Class

public partial class Product
{
    public Product()
    {
        this.OrderCheckouts = new HashSet<OrderCheckout>();
        this.ProductReviews = new HashSet<ProductReview>();
    }

    public int ProductID { get; set; }
    public int CategoryID { get; set; }
    public int ManufacturerID { get; set; }
    public string ProductName { get; set; }
    public string ProductCode { get; set; }
    public decimal UnitCost { get; set; }
    public int UnitQuantity { get; set; }
    public string ProductDescription { get; set; }
    public string ProductImage { get; set; }

    public virtual Category Category { get; set; }
    public virtual Manufacturer Manufacturer { get; set; }
    public virtual ICollection<OrderCheckout> OrderCheckouts { get; set; }
    public virtual ICollection<ProductReview> ProductReviews { get; set; }
}

ShoppingBasket Class

public partial class ShoppingBasket
{
    public int CartID { get; set; }
    public string BasketID { get; set; }
    public int BasketQuantity { get; set; }
    public int ProductID { get; set; }
    public virtual Product Product { get; set; }
}

Could someone explain the problem more clearly and how I can solve this? Thanks!

Answer 1

I think it's because Entity Framework hasn't fully created the relationship between ShoppingBasket and Product . Try adding:

public virtual ICollection<ShoppingBasket> ShoppingBaskets { get; set; }

to the Product class.