How to add item to the beginning of List<T>?

Question

I want to add a "Select One" option to a drop down list bound to a List<T>.

Once I query for the List<T>, how do I add my initial Item, not part of the data source, as the FIRST element in that List<T> ? I have:

// populate ti from data               
List<MyTypeItem> ti = MyTypeItem.GetTypeItems();    
//create initial entry    
MyTypeItem initialItem = new MyTypeItem();    
initialItem.TypeItem = "Select One";    
initialItem.TypeItemID = 0;
ti.Add(initialItem)  <!-- want this at the TOP!    
// then     
DropDownList1.DataSource = ti;

Answer 1

Use the Insert method:

ti.Insert(0, initialItem);

Answer 2

Update: a better idea, set the "AppendDataBoundItems" property to true, then declare the "Choose item" declaratively. The databinding operation will add to the statically declared item.

<asp:DropDownList ID="ddl" runat="server" AppendDataBoundItems="true">
    <asp:ListItem Value="0" Text="Please choose..."></asp:ListItem>
</asp:DropDownList>

http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.listcontrol.appenddatabounditems.aspx

-Oisin

Answer 3

Use List<T>.Insert

While not relevant to your specific example, if performance is important also consider using LinkedList<T> because inserting an item to the start of a List<T> requires all items to be moved over. See When should I use a List vs a LinkedList.

Answer 4

Use Insert method of List<T>:

List.Insert Method (Int32, T): Inserts an element into the List at the specified index.

var names = new List<string> { "John", "Anna", "Monica" };
names.Insert(0, "Micheal"); // Insert to the first element