Loading DropDownList from Enumeration in ASP.NET

Introduction:

This article shows how to load DropDownList from Enumeration using extension methods. Example in this demo loads DropDownlists from DayOfWeek and SpecialFolders Enumerations respectively.

Background:

Extension Methods often helps extend base functionality of an object by refactoring code. Unfortunately, Classes such as System.Enum, System.Object cannot be extended like a string or integer type. There are different ways to convert Enumeration to a List but I prefer using Enum GetNames and GetValues methods to make a list.

Markup:

html>
<head runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
    <table style="font-family: Tahoma; font-size: small;">
        <tr>
            <td>
                Day:
            </td>
            <td>
                <asp:DropDownList ID="ddlWeekOfDay" Width="200px" runat="server" DataTextField="Text"
                    DataValueField="Value" 
                    onchange="weekOfDay.innerHTML='Selected Item: '+ 
                              this.options[this.selectedIndex].text+
                              '('+this.options[this.selectedIndex].value+')';">
                </asp:DropDownList>
            </td>
            <td>
                <span id="weekOfDay"></span>
            </td>
        </tr>
        <tr>
            <td>
                Special Folder:
            </td>
            <td>
                <asp:DropDownList ID="ddlSpecialFolder" runat="server" DataTextField="Text" DataValueField="Value"
                    Width="200px" 
                    onchange="specialFolder.innerHTML='Selected Item: '+ 
                              this.options[this.selectedIndex].text+
                              '('+this.options[this.selectedIndex].value+')';">
                </asp:DropDownList>
            </td>
            <td>
                <span id="specialFolder"></span>
            </td>
        </tr>
    </table>
    </form>
</body>
</html>
CodeBehind:


using System;
using System.Linq;
//Extension methods 
public static class EnumHelper 
{ 
    public static object ToList(this Enum T) 
    {
        Array values = Enum.GetValues(T.GetType()); 
        return Enum.GetNames(T.GetType()).ToList().Select((a, index) => new {
            Text = a, Value = (Int32)values.GetValue(index) }) .OrderBy(a=>a.Text); 
    } 
} 
protected void Page_Load(object sender, EventArgs e) 
{
    if (!IsPostBack) 
    { 
        ddlWeekOfDay.DataSource = DayOfWeek.Friday.ToList(); 
        ddlWeekOfDay.DataBind(); 
        ddlSpecialFolder.DataSource = Environment.SpecialFolder.AdminTools.ToList(); 
        ddlSpecialFolder.DataBind(); 
    } 
}
Conclusion:
Another option is adding ListItems to DropDownList by looping Enumeration Values. Type can also be extended instead of Enum.

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