Question

I’m following this guide and I am getting an error. Can anyone help me?

The code for my datamodel is below

  namespace Datalayer {
    public class DataModel {

        public DataModel()
        {
            using (btWholesaleDataContext db = new btWholesaleDataContext()) {
                //! requires auth
                var MACRequestList = from r in db.btRequests
                                     select new Models.BT.Request {
                                         ID = r.ID,
                                         Date = r.DateTime,
                                         StatusCode = 3,
                                         Status = r.Status
                                     };

                MACRequests = MACRequestList.AsQueryable();

            }
        }

        public IQueryable<Models.BT.Request> MACRequests { get; private set; }
    }
}

The web service gives the error

Cannot access a disposed
object.Object name: ‘DataContext
accessed after Dispose.’

When I access MACRequests

I have only posted the code I think is broken. If you want to see more just let me know.

Answer 1

Your data context is being disposed at the end of your constructor, at the end of the using { } block. However when you use the IQueryable MACRequests property, it needs that underlying context, which has since been disposed.

One possible way to handle this is to make your class IDisposable and dispose the context that way:

public class DataModel : IDisposable {

    private btWholesaleDataContext wholesaleDataContext;

    public DataModel()
    {
        wholesaleDataContext = new btWholesaleDataContext();
        //! requires auth
        var MACRequestList = ... ;

        MACRequests = MACRequestList.AsQueryable();
    }

    public IQueryable<Models.BT.Request> MACRequests { get; private set; }

    public void Dispose() {
        if(wholesaleDataContext != null)
            wholesaleDataContext.Dispose();
    }
}

Then you have to make sure that DataModel is properly disposed by whatever uses it.

Another alternative is to make MACRequests the actual list of items instead of the IQueryable:

public class DataModel {

    public DataModel()
    {
        using (btWholesaleDataContext db = new btWholesaleDataContext()) {
            //! requires auth
            var MACRequestList = ... ;

            MACRequests = MACRequestList.ToList(); // ToList reads the records now, instead of later.

        }
    }

    public List<Models.BT.Request> MACRequests { get; private set; }
}