Question

My model is implemented in an own DLL, where also the generated App.config is placed. The application itself “had” no App.config. No context was initialized (direct access in DLL only). And i get an error, which was solved by copy the connection string into the application new by hand generated App.config.

This case was a little bit redundant for me and I decided to get the EntityConnection by writing it myself. Now the problematic code, which works with the redundant version and not in the own implementation.

public Discount GetDiscountByOffer(int discountId)
{
    // Own implementation, redundant one without passed connection parameter
    using (context2 = new SalesEntities(Configuration.EntityConnection))
    {
        return context2.Discounts.Single(d => d.ID == discountId);
    }
}

In another class I call this method and assign it to a customer. Also here i make a new context. Code simplified:

    // Own implementation, redundant one without passed connection parameter
    using (context1 = new SalesEntities(Configuration.EntityConnection))
    {
        var customer = GetCustomer(10004);
        customer.ActualDiscount = GetDiscountByOffer(5); // here is the call and 
                                                         // the error
    }

The error ahows that ObjectContext (context1) was closed, what I don’t understand. What has context2 to do with context1? I bet that both share the same reference, but it’s not logical for me. The EntityConnection is also initialized new each time I pass the parameter.

In the redundant version this code works.

Answer 1

Get the object from context2, attach it to context1, then set the customer’s property.

MSDN explanation:

http://msdn.microsoft.com/en-us/library/system.data.objects.objectcontext.attach.aspx

Read ‘The problems of working with multiple ObjectContext instances’ below:

http://dotnetslackers.com/articles/ado_net/Managing-Entity-Framework-ObjectContext-lifespan-and-scope-in-n-layered-ASP-NET-applications.aspx#the-problems-of-working-with-multiple-objectcontext-instances