Question

I have this method AddSection

public ActionResult AddSection(string code, ArrayList added)
    {
        ArrayList list = added;
        if (list == null) list = new ArrayList();
        list.Add(Request["selected_section"]);
        return RedirectToAction("Details", new { code = code, added = list });
    }

Which redirects to the Details:

public ActionResult Details(string code, ArrayList added)
    {
        if (added == null) added = new ArrayList();
        return View(added);
    }

Now in the Details action(if it’s rendered from the AddSection) the “added” ArrayList should never be null because it’s initialized anyway in AddSection and passed to the Details.
When I debug the program “added” ArrayList in Details is null even if the action rendered after AddSection.

Can someone explain why?

Answer 1

Like LukeP said, it looks like a dup because as the other question/answer states, only the primitive types can be passed, not complex types.

To modify your code you can do this

public ActionResult AddSection(string code, ArrayList added) {
    ArrayList list = added;
    if (list == null) list = new ArrayList();
    list.Add(Request["selected_section"]);
    TempData["ListOfValues"] = list;
    return RedirectToAction("Details", new { code = code});
}

public ActionResult Details(string code) {
    var added = (ArrayList)TempData["ListOfValues"];
    if (added == null) added = new ArrayList();
    return View(added);
}