Strange problem with two different objects having reference

Question

When a ClaimDetail is added to tmpClaim, this ClaimDetail is also added to claim. Can someone explain me why this occurs?

List<Claim> claims; // list data
foreach ( Claim claim in claims) {
  Claim tmpClaim = datacontext.Claims.FirstOrDefault ( c => c.Id == claim.Id );

  ClaimDetail claimDetail = new ClaimDetail ( );
  claimDetail.ClaimDetailType = "Type";

  // add claim
  datacontext.Claims.InsertOnSubmit ( tmpClaim );
  datacontext.SubmitChanges ( );
}

Answer 1

tmpClaim isn't a new object. It's still a reference back to an element within claims .

What this essentially means is that whatever you do to tmpClaim is also happening with claims . They are the same thing.

If you don't want changes to tmpClaim to affect claims , you'll need to create a new Claim (as well as any copying/cloning that is necessary) and do all of your work on that new object.