Attaching entities to data contexts

Question

In LINQ to SQL, is it possible to check to see if an entity is already part of the data context before trying to attach it?

A little context if it helps...

I have this code in my global.asax as a helper method. Normally, between requests, this isn't a problem. But right after signing in,this is getting called more than once and the second time I end up trying to attach the Member object in the same unit of work where it was created.

private void CheckCurrentUser()
{
   if (!HttpContext.Current.User.Identity.IsAuthenticated)
   {
      AppHelper.CurrentMember = null;
      return;
   }

   IUserService userService = new UserService();

   if (AppHelper.CurrentMember != null)
      userService.AttachExisting(AppHelper.CurrentMember);
   else
      AppHelper.CurrentMember = userService.GetMember(
         HttpContext.Current.User.Identity.Name,
         AppHelper.CurrentLocation);
}

Answer 1

I believe there are two methods to do this.

DataContext.TableName.Contains(Item)

or we use the id field. If the item is inserted in the Database, then it will be assigned a row.

if(Item.id == 0)
   DataContext.Insert(Item)
else
   DataContext.Update(Item)

Answer 2

Rather than attaching to a new data context why not just requery the object in the new datacontext? It believe it is a more reliable and stateless strategy.