CODEWITHSUNDEEP
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Reputation: 184

EF 4.1: Cannot Add Collection - Object reference not set to an instance of an object

I was told by JL herself I needed to disable lazy loading and remove virtuals from my code, so:

I. The Domain:

    public class Parent
    {
        public int Id { get; set; }
        public ICollection<Child> Children { get; set; }
    }

    public class Child
    {
        public int Id { get; set; }
        public int FK_ParentId { get; set; }            

        [ForeignKey("FK_ParentId")]
        public Parent Parent { get; set; }
    }

II. DAL:

   public DataContext()
   {
      this.Configuration.LazyLoadingEnabled = false;
   }

III. program.cs 

        var clientSvc = new ClientSvcRef.ServiceClient();            
        var parent = new Parent();
        var child = new Child {Parent = parent};
        parent.Children.Add(child);
        clientSvc.AddParent(parent);

The problem: Line 4 in program.cs: "Object reference not set to an instance of an object."

Upvotes: 2

Views: 2013

Answers (1)

Sergey Kalinichenko
Sergey Kalinichenko

Reputation: 726509

There are at least two ways to deal with this issue:

(1) initialize collection yourself in the constructor, 

public Parent() {
    Children = new List<Child>();
}

or (2) use Create() instead of new:

var p = _db.Parents.Create();
var c = _db.Children.Create();
c.Parent = p;

Upvotes: 4

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