Question

We are using List<object> type as datasource for dropdownlist.

Process flow:

1. Assign value (List<object>) to the session in the pageload event(!ispostback).
2. Retrieve value from session in ddl_SelectedIndexChanged event
3. Remove a particular item from the list and bind to the ddl

Code:

List<Loc> locList = new List<Loc>();
locList =  (List<Loc>)Session["Loc"];
locID = "xxx";

locList.RemoveAt(locList.FindIndex(FindLocation));

Problem:

Item is getting removed from the base source also (session).

Answer 1

The problem is that you’re manipulating the list that is stored in the session, not a copy. Instead, if you do something like this:

List<Loc> locList = new List<Loc>((List<Loc>)Session["Loc"]);
locID = "xxx";

locList.RemoveAt(locList.FindIndex(FindLocation));

you’re operating on a copy of the list, and the original won’t change.