autopostback on dropdownlist

[TJS]

I am rendering a dropdownlist from HTMLTextWriter, how do I specify to
enable autopostback ?

'=========================================
....
writer.AddAttribute(HtmlTextWriterAttribute.Id, "xx")
writer.AddAttribute(HtmlTextWriterAttribute.Name, "xx")
writer.RenderBeginTag(HtmlTextWriterTag.Select)

writer.AddAttribute( HtmlTextWriterAttribute.Value, "-1" )
writer.RenderBeginTag(HtmlTextWriterTag.Option)
writer.Write( HttpUtility.HtmlEncode("-- All --") )
writer.RenderEndTag()

writer.RenderEndTag()
....

 

[Guest]

You can implement IPostBackDataHandler interface for your purpose.For example:
class MyDropDownList:WebControl,IPostBackDataHandler{
// below,your must implement IPostBackDataHandler's method.
bool LoadPostData(string postDataKey, NameValueCollection postCollection){
// check postback data here
}

void RaisePostDataChangedEvent(){
// raise your event here.
}
}

 

[Eliyahu Goldin]

Enabling autopostback is a server-side task. Asp.net knows how to translate
"AutoPostBack=true" instruction to a set of client-side commands supported
on the server-side. HtmlTextWriter produces pure client code. To reproduce
autopostback behavior on this level, you need to know what to put into the
page output and what to handle on server side. Don't reinvent wheel, just
use normal asp:dropdownlist.

Eliyahu

 

[TJS]

here is the answer which was found to work

writer.AddAttribute(HtmlTextWriterAttribute.Onchange,
Page.GetPostBackEventReference(Me))