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LiveDropDownList ASP.NET Server Control Information

LiveListBox ASP.NET Server Control Information

This page includes information about the LiveDropDownList and LiveListBox Server Controls, which are included in PowerWEB LiveControls for ASP.NET:

[View LiveControl Demo]

The LiveDropDownList and LiveListBox (both of which represent an HTML SELECT element) server controls replace the standard ASP.NET DropDownList and ListBox server controls, using remote-scripted callback technology in place of postback technology. As a result, a user is able to select an item of these lists, raising a server-event, and update client-side elements without refreshing the browser. This enables the creation of web applications which have an unprecedented level of responsiveness.

Remember! Any LiveControl which raises a callback to the server (such as LiveButton, LiveImageButton, and LiveLinkButton) raises a server event within which ANY client-side element can be visually updated without refreshing the page!

The LiveDropDownList and LiveListBox controls have the following features:

  • Cross-browser compatible, no plugins, downloads, or security warnings.
  • Uses same interface as the standard ASP.NET DropDownList and ListBox , so there is no learning curve.
  • Bind data on postback and visual update occurs client-side without a refresh.

Some example uses for LiveDropDownList and LiveListBox:

  • Create a form for a configurable product (such as Dell's "configure your computer" form) which updates the price as various options are selected/deselected.
  • Display heirachical data, displaying the items of the next node in a list as each parent node is selected.
  • Use LiveDropDownList in conjunction with LiveDataGrid to display a column which contains a dropdown in each cell.


Browser Compatibility

LiveControls have been tested and are fully "callback-compatible" in the following browsers:

  • Microsoft Internet Explorer 5.0+ for Windows
  • Microsoft Interner Explorer 5.0+ for Macintosh
  • Netscape 7.1+ for Windows
  • Netscape 7.1+ for Macintosh OS X
  • Mozilla 1.3+ for Windows
  • Mozilla 1.3+ for Macintosh OS X
  • Firefox for Windows
  • Firefox for Macintosh OS X
  • Camino for Macintosh OS X
  • Konqueror based engines
  • Galeon
  • Opera 5.0+

If a browser which is not compatible accesses a page containing LiveControls, the controls will fall back to the standard ASP.NET functionality. For example, a LiveButton issues a transparent callback when clicked. If on a non-compatible page, the button will still be displayed, but will cause a standard postback when clicked.

Server Tag Example

The following tags demonstrate typical settings for initializing a LiveButton, LiveLinkButton, and LiveImageButton.

<cc1:LiveDropDownList id="LiveDropDownList1" runat="server"></cc1:LiveDropDownList>
<cc1:LiveListBox id="LiveDropDownList1" runat="server"></cc1:LiveLiveBox>

Code-Behind Example

This demonstrates binding the LiveDropDownList and handling the LiveDropDownList.SelectedIndexChanged event.

// Bind some test data
ArrayList list1 = new ArrayList();
list1.Add("item 1");
list1.Add("item 2");
list1.Add("item 3");
list1.Add("item 4");
LiveDropDownList1.DataSource = list1;

// Handle SelectedIndexChanged event
private void LiveDropDownList1_SelectedIndexChanged(object sender, System.EventArgs e)
   LiveLabel1.Text = LiveDropDownList1.SelectedItem.Text;