How to attach object to existing property using Entity Framework

Question

I have a property that contains a list from an entity in my model. I want to add an item to this list but when I do, it's added as detached. How can I add this object as attached?

using (var db = new fsEntities())
{
   var list = db.Products.Where(x => x.ID == 1).ToList();
   var p = new Product { Description = "New Item", Amount = 14};
   list.Add(p);   //the new item EntityState is detached
}

I know I can do this, db.AddToProducts(p), but in my scenario I want to add the object to the existing property with it's EntityState as attached, then later perform a SaveChanges if necessary.

How can I do this?

Its usual when you are adding new object - it is in Detached state by default. Only in Insert method that generates for you EntityState changed to Added. — Anatolii Gabuza
– Anatolii Gabuza, Commented Jan 28, 2012 at 0:11

Eranga · Accepted Answer · 2012-01-28 00:02:20Z

1

You can attach the entity. This will be added to the context with Unchanged state.

using (var db = new fsEntities())
{
   var list = db.Products.Where(x => x.ID == 1).ToList();
   var p = new Product { Description = "New Item", Amount = 14};

   db.Attach(p);

   list.Add(p);   //the new item EntityState is detached
}

answered Jan 28, 2012 at 0:02

Eranga

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1 Comment

Jerry Over a year ago

Actually, my problem was getting the new item's entity state to be "added" instead of "detached". This does what I need it to do. db.Products.AddObject(item); list.Add(item);

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