Yesterday I needed a way to sort the items in a ListControl (in this case, a DropDownList) after the list had been populated. The reason for that is after I databound my DropDownList from a collection of items, I inserted a few more ListItems depending on certain circumstances. Instead of trying to hack some method of inserting those items in my original collection, I wanted a more elegant solution. After I came across a post on Google I came up with a solution using an extension method and LINQ:
public static void Sort(this ListItemCollection items) { IList<ListItem> itemList = new List<ListItem>(); foreach (ListItem item in items) itemList.Add(item); IEnumerable<ListItem> itemEnum = from item in itemList orderby item.Text select item; items.Clear(); items.AddRange(itemEnum.ToArray()); } //example - assume MyDropDownList is a DropDownList on the aspx page MyDropDownList.DataSource = SomeMethodThatReturnsAList(); MyDropDownList.DataBind(); MyDropDownList.Items.Insert(0, new ListItem("My Display String", "My List Value")); //this will sort all the items based on ListItem.Text MyDropDownList.Items.Sort();
I wanted a simple solution so I didn't do any performance metrics on it. Things I might change is the add ability to sort by ListItem.Value, add the ability to change the sort direction, or perhaps sort by a custom comparer. So if you want a way to sort a ListItemCollection, give this a try and let me know what you think! :)
