EF 4.1 - Add items to collection property that is virtual

I'm using EF 4.1 code first. Given the following class snippet:

public class Doctor
{
    public virtual ICollection<Hospital> Hospitals { get; set; }
}

Note: I have this in the database context:

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    this.Configuration.LazyLoadingEnabled = false;
}

I wanted to make sure that lazy loading is not involved here.

The issue I have is that, without the virtual keyword on the Hospitals property, when I retrieve a doctor that does have a hospital associated with him, the collection is empty. By including the virtual keyword, the hospitals collection does contain 1 item, which is what I expect.

The problem is that, when I want to create a brand new doctor and associate him with a hospital immediately, I get a Null reference exception, since the Hospitals property has not been initialised yet.

Can someone point out what I'm doing wrong here? How can I开发者_如何学C add items to the Hospitals upon creating a new doctor.

Cheers. Jas.

Your code is something what you usually see in all examples but to make this work this one is much better:

public class Doctor
{
    private ICollection<Hospital> _hospitals;
    public virtual ICollection<Hospital> Hospitals 
    { 
        get { return _hospitals ?? (_hospitals = new HashSet<Hospital>()); }
        set { _hospitals = value } 
    }
}

If you don't use virtual keyword EF will not initialize collection for you. In the same time if you create brand new Doctor via its constructor you must handle initialization yourselves.

I think this can help you.

public class Doctor
{
    public Doctor()
    {
       Hospitals = new ICollection<Hospital>();
    }

    public virtual ICollection<Hospital> Hospitals { get; set; }
}