The EntityKey property can only be set when the current value of the property is null

Question

i'm trying to execute an EF update in the following manner but continue to receive this error:

The EntityKey property can only be set when the current value of the property is null.

        using (hydraEntities db = new hydraEntities())
        {
            YouUser = db.youusers.Include("address").Include("entity").Include("youusercontacts.contact").Include("youuserlogins").Include("youusernotes.note").Include("youusernotes.youuser.entity").Where( yu => yu.YOUUserId.Equals(YOUUserId)).First();
        }

            YouUser.entity.FirstName = txtFirstName.Text;
            YouUser.entity.LastName = txtLastName.Text;
            YouUser.address.AddressLine1 = txtAddressLine1.Text;
            YouUser.address.AddressLine2 = txtAddressLine2.Text;
            YouUser.address.City = txtCity.Text;
            YouUser.address.State = ddlState.SelectedValue;
            YouUser.address.Zipcode = txtZipcode.Text;

            using (hydraEntities db = new hydraEntities())
            {
                db.youusers.AddObject(YouUser);
                db.ObjectStateManager.ChangeObjectState(YouUser, System.Data.EntityState.Modified);
                db.SaveChanges();
            }

Would greatly appreciate any insight on how I can fix this and execute the statement above.

Answer 1

Don't use AddObject in this scenario. It is for inserting a new entity but you are updating existing one. Use Attach instead:

using (hydraEntities db = new hydraEntities())
{
    db.youusers.Attach(YouUser);
    db.ObjectStateManager.ChangeObjectState(YouUser, System.Data.EntityState.Modified);
    db.SaveChanges();
}