实体框架上下文可以返回继承实体的类吗

Question

I have an Entity Framework 5 Code First DbContext

public class ProductContext : DbContext
{
    public DbSet<Product> Products {get;set;}
}

public class Product
{
    public int ProductId { get; set; }
    public string Name { get; set; }
}

Now I have to implement an interface but don't want to pollute my model so I create a

public class ProductEx : Product, ISomeInterface
{
    public bool ISomeInterface.SomeMethod() { return false; }
}

I know I could do:

var query = from p in context.Products
            select new ProductEx { p.ProductId, p.Name };

But since the DbContext already returns a dynamic proxy (because of change tracking / lazy loading) maybe there is a better approach. I am thinking about something like this:

var query = from p in context.Products.As<ProductEx>()
            select p;

the entities should be a dynamic proxy inherited from ProductEx.

Is there a way to achive this?

Answer 1

One way is to You can create a wrapper for product:

public class Product
{
    public virtual int ProductId { get; set; }
    public virtual string Name { get; set; }
}

public class ProductEx : Product, ISomeInterface
{
    private readonly Product _product;

    public ProductEx(Product product) {
        this._product = product;
    }

    public bool ISomeInterface.SomeMethod() { return false; }

    public override int ProductId
    { 
        get { return this._product.ProductId; }
        set { this._product.ProductId = value; }
    }

    public override string Name
    { 
        get { return this._product.Name; }
        set { this._product.Name = value; }
    }
}

Then you can query liko so:

var query = from p in context.Products
        select new ProductEx(p);