TreeView checkboxes AutoPostBack with AJAX

[Dmitry Perets]

Hello,

There is a known problem with TreeView checkboxes in ASP.NET: they can't do AutoPostBack. So I've solved this problem like this:

<script language="javascript" type="text/javascript">

function postbackOnCheck()
{
var o = window.event.srcElement;
if (o.tagName == 'INPUT' && o.type == 'checkbox' &&
o.name != null && o.name.indexOf('CheckBox') > -1)
{
__doPostBack("","");
}
}

</script>

<asp:TreeView onclick="postbackOnCheck()" ID="treeContent"
runat="server"> ... And so on ... </TreeView> This way I get full postback each time the user checks\unchecks the checkbox.

But now I want to modify this code in order to make use of AJAX: I don't want the FULL postback, but I only want the tree itself to be updated. Of course, I've started by placing it inside the UpdatePanel. But what now? Can somebody help me with this issue?

[PeejAvery]

AJAX does a wonderful job of altering the innerHTML content of DIV tags. Why don't you just re-write that content with the new treeview?

[Dmitry Perets]

AJAX does a wonderful job of altering the innerHTML content of DIV tags. Why don't you just re-write that content with the new treeview?

Hmmm... Can you please give me an example?

[PeejAvery]

It's the most basic form of AJAX. Take a look here (http://w3schools.com/ajax/ajax_intro.asp).

<div id="theDIV"><div>

<script language="JavaScript">
var theDIV = document.getElementById('theDIV');
theDIV.innerHTML = "This will be the DIV's content.";
</script>

[Dmitry Perets]

No, that won't work for me... There has to be a postback, because my tree is dynamic, it is filled in "lazy" mode on server-side. So I can't check the checkboxes on the client-side - they may not exist there at all...

Do you know how can I update the update panel on the client-side? I know that there is some way using PageRequestManager... But I can't find how exactly this works. This is the only thing I need to solve the issue now...

[PeejAvery]

Do you know how can I update the update panel on the client-side?
That is exactly what I am trying to show you. AJAX sends data to the server and then sends the data back to the client-side. Did you even browse into the link I posted? There are more pages there to browse. Read the whole AJAX section.