Exception of type 'System.ObjectDisposedException'

Question

I have following EF code first code. It is working fine. But when I look for the value of 'club2.Members', it says following:

'club2.Members' threw an exception of type 'System.ObjectDisposedException'.

Message is:

The ObjectContext instance has been disposed and can no longer be used for operations that require a connection.

I have not set value for Members property. That’s okay. However it should not cause any exception internally.

1. Is there a way to overcome this exception?
2. Does removal of this exception help in improving performance?
3. Why this exception did not cause termination of program execution?

Note: I don't need the Members data in club entity (at the point where I have called). Even there is no members added to the club at that time. All i need is to get rid of the exception; not to load data using eager load. How to avoid the exception?

namespace LijosEF
{

public class Person
{
    public int PersonId { get; set; }
    public string PersonName { get; set; }
    public virtual ICollection<Club> Clubs { get; set; }
}

public class Club 
{
    public int ClubId { get; set; }
    public string ClubName { get; set; }
    public virtual ICollection<Person> Members { get; set; }

}




//System.Data.Entity.DbContext is from EntityFramework.dll
public class NerdDinners : System.Data.Entity.DbContext
{

    public NerdDinners(string connString): base(connString)
    { 

    }

    protected override void OnModelCreating(DbModelBuilder modelbuilder)
    {
         //Fluent API - Plural Removal
        modelbuilder.Conventions.Remove<PluralizingTableNameConvention>();
    }

    public DbSet<Person> Persons { get; set; }
    public DbSet<Club> Clubs { get; set; }



}
}




    static void Main(string[] args)
    {
        Database.SetInitializer<NerdDinners>(new MyInitializer());

        CreateClubs();
        CreatePersons();

    }

    public static void CreateClubs()
    {

        string connectionstring = "Data Source=.;Initial Catalog=NerdDinners;Integrated Security=True;Connect Timeout=30";
        using (var db = new NerdDinners(connectionstring))
        {

            Club club1 = new Club();
            club1.ClubName = "club1";

            Club club2 = new Club();
            club2.ClubName = "club2";

            Club club3 = new Club();
            club3.ClubName = "club3";

            db.Clubs.Add(club1);
            db.Clubs.Add(club2);
            db.Clubs.Add(club3);

            int recordsAffected = db.SaveChanges();


        }
    }

    public static Club GetClubs(string clubName)
    {
        string connectionstring = "Data Source=.;Initial Catalog=NerdDinners;Integrated Security=True;Connect Timeout=30";
        using (var db = new NerdDinners(connectionstring))
        {

            var query = db.Clubs.SingleOrDefault(p => p.ClubName == clubName);
            return query;
        }
    }

    public static void CreatePersons()
    {
        string connectionstring = "Data Source=.;Initial Catalog=NerdDinners;Integrated Security=True;Connect Timeout=30";
        using (var db = new NerdDinners(connectionstring))
        {

            Club club1 = GetClubs("club1");
            Club club2 = GetClubs("club2");
            Club club3 = GetClubs("club3");

             //More code to be added (using db) to add person to context and save
        }
    }

Answer 1

You're getting this error because you are disposing the dbcontext after you execute the query. If you want to use the data in "members" then load it with the query: http://blogs.msdn.com/b/adonet/archive/2011/01/31/using-dbcontext-in-ef-feature-ctp5-part-6-loading-related-entities.aspx

If you don't need lazy loading, which means that only data you're loading in the query is loaded (this will eliminate the exception), set LazyLoadingEnabled = false. Look here: Disable lazy loading by default in Entity Framework 4