I needed a list of user to populate a DropDownList. In DotNetNuke, you can get an ArrayList of all users on the system with a call to: UserController.GetUsers(int PortalID).
The problem is the list is sorted by UserID, so when you open the DDL, you'll see all the users in what seems to be random order. I wanted the list to be sorted by LastName, FirstName without having to write some sort of IComparer.
This is a great use case for Linq ( I've heard a lot about it, but never used it).
ArrayList a = UserController.GetUsers(0);
var so = from UserInfo s in a orderby s.LastName,s.FirstName select s;
ddlUser.DataSource = so;
ddlUser.DataValueField = "UserID"; // Alias Name from Sproc
ddlUser.DataTextField = "DisplayName"; // Alias name from sproc
ddlUser.Items.Insert(0, new ListItem("Select One", "0")); // Adds items to DDL
If you are using a custom object (ie UserInfo), then you must explicitly declare the type.
When using LINQ to query non-generic IEnumerable collections such as ArrayList, you must explicitly declare the type of the range variable to reflect the specific type of the objects in the collection.