Newbie: trouble with the tutorial

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2 posts, 1 answers
  1. ColdCold
    ColdCold avatar
    2 posts
    Member since:
    Jul 2007

    Posted 14 Sep 2009 Link to this post

    Hello all,

    I just started working through the first tutorial in the "OpenAccess Made Easy" book and I'm running into a problem already... must be something simple.  I am getting NullReferenceException (Object reference not set to an instance of an object.) at the line "customer.Orders.Add(order);".  Not sure why.  The tables in the DB get created just fine, but then I hit this exception.  It's a simple console application.  Here is my code:

    class Program


        static void Main(string[] args)



            IObjectScope scope = ObjectScopeProvider1.ObjectScope();




            Customer customer = new Customer();

            customer.CustomerName =




            customer.CustomerNumber = 123;


    order = new Order();

            order.OrderNumber = 1;

            customer.Orders.Add(order);  // <--- exception happens here.









    public class Customer



        private int customerNumber;


        public int CustomerNumber



            get { return customerNumber; }


            set { customerNumber = value; }




        private string customerName;


        public string CustomerName



            get { return customerName; }


            set { customerName = value; }




        private IList<Order> orders; 


        public IList<Order> Orders



            get { return orders; }


            set { orders = value; }









    public class Order



        private int orderNumber;


        public int OrderNumber



            get { return orderNumber; }


            set { orderNumber = value; }





    thanks in advance for your help.




  2. Answer
    PetarP avatar
    754 posts

    Posted 14 Sep 2009 Link to this post

    Hi ColdCold,

    You are getting this exception because the collection has not been initialized. To put this into code, you should change this line:
    private IList<Order> orders;  
    private IList<Order> orders = new List<Order>();  
    Please note that this exception is not caused by Telerik OpenAccess ORM.

    Best wishes,
    the Telerik team

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