How do I add an item to a TreelistEx using C#?

Question

I can't seem to find any documentation on this. I have an item, that has a TreelistEx field:

I want to programatically add a new item to this field, preferably using glass mapper but vanilla sitecore will do if needs must.

Can anyone help me out here? How do I go about this?

You'll have to excuse the lack of details, I can't find a single thing to point me in the right direction here.

Answer 1

The TreeList and TreeListEx work the same way as the multilist.

using (new Sitecore.SecurityModel.SecurityDisabler())
{

    Item newItem = Sitecore.Context.Item;

    newItem.Editing.BeginEdit();

    MultilistField mlf = newItem.Fields["FieldName"];

    // adding an item
    mlf.Add(ItemToAdd.ID.ToString());

    // removing an item
    mlf.Remove(ItemToRemove.ID.ToString());

    newItem.Editing.EndEdit();
}