Question

I need to attach EF object (previously detached) to a new ObjectContext. The problem is that I don’t know if it was attached or loaded before. And if there is an object with the same key loaded to ObjectContext I get an exception when I try to attach. Is there a way to check if there is an object with a particular key already attached?

Thanks!

Answer 1

The state of objects inside an object context is managed by the ObjectStateManager.

from MSDN:

int orderId = 43680;

using (AdventureWorksEntities context =
    new AdventureWorksEntities())
{
    ObjectStateManager objectStateManager = context.ObjectStateManager;
    ObjectStateEntry stateEntry = null;

    var order = (from o in context.SalesOrderHeaders
                 where o.SalesOrderID == orderId
                 select o).First();

    // Attempts to retrieve ObjectStateEntry for the given EntityKey.
    bool isPresent = objectStateManager.TryGetObjectStateEntry(((IEntityWithKey)order).EntityKey, out stateEntry);
    if (isPresent)
    {
        Console.WriteLine("The entity was found");
    }
}

Also see: http://msdn.microsoft.com/en-us/library/dd456854.aspx

from previous MSDN link:

// The changes are tracked as they occur and the state of the object is Modified.
Console.WriteLine(context.ObjectStateManager.GetObjectStateEntry(newItem).State);

.. I suppose that in your case this could be one of the cached item.

Hope it helps!