Options added to select list with JavaScript lost on postback

[Mario Vargas]

Hello all,

I am trying to dynamically add elements to a select list (which is running
on the server, runat="server") with JavaScript, but when I postback, the new
elements are lost. I'm not sure how to tell ASP.Net to post back these new
elements as well. Any ideas or sources where you could point me to will be
greatly appreciated. I am still using ASP.Net 1.1.

This is part of the code I am using to dynamically add the element:

myOpenerListCtr l.options[myOpenerListCtr l.options.lengt h] = new Option(
districtName, districtID );

I also tried using standard DOM syntax:

var newOption = document.create Element( "option" );
newOption.setAt tribute( "value", districtID );
newOption.inner Text = districtName;
myOpenerListCtr l.appendChild( newOption )

But neither is kept in the postback.

Thanks!

Mario

[Steve C. Orr [MCSD, MVP, CSM, ASP Insider]]

Re: Options added to select list with JavaScript lost on postback

Most people add such data to a hidden form field, which you would then
manually process upon postback to keep the lists in sync on both ends.

--
I hope this helps,
Steve C. Orr,
MCSD, MVP, CSM, ASPInsider

http://SteveOrr.net

"Mario Vargas" <mariovargas@th ecourier.comwro te in message
news:eR1DfYEtHH A.508@TK2MSFTNG P02.phx.gbl...

Hello all,
>
I am trying to dynamically add elements to a select list (which is running
on the server, runat="server") with JavaScript, but when I postback, the
new elements are lost. I'm not sure how to tell ASP.Net to post back these
new elements as well. Any ideas or sources where you could point me to
will be greatly appreciated. I am still using ASP.Net 1.1.
>
This is part of the code I am using to dynamically add the element:
>
myOpenerListCtr l.options[myOpenerListCtr l.options.lengt h] = new Option(
districtName, districtID );
>
I also tried using standard DOM syntax:
>
var newOption = document.create Element( "option" );
newOption.setAt tribute( "value", districtID );
newOption.inner Text = districtName;
myOpenerListCtr l.appendChild( newOption )
>
But neither is kept in the postback.
>
Thanks!
>
Mario
>

[Mario Vargas]

Re: Options added to select list with JavaScript lost on postback

Thanks, Steve! I also thought about this approach, but was hoping for a
better way...

Mario

"Steve C. Orr [MCSD, MVP, CSM, ASP Insider]" <Steve@Orr.netw rote in
message news:5D2AC4B3-D24B-41C4-85D0-36A429E94F0F@mi crosoft.com...

Most people add such data to a hidden form field, which you would then
manually process upon postback to keep the lists in sync on both ends.
>
--
I hope this helps,
Steve C. Orr,
MCSD, MVP, CSM, ASPInsider

http://SteveOrr.net

>
>
"Mario Vargas" <mariovargas@th ecourier.comwro te in message
news:eR1DfYEtHH A.508@TK2MSFTNG P02.phx.gbl...

>Hello all,
>>
>I am trying to dynamically add elements to a select list (which is
>running on the server, runat="server") with JavaScript, but when I
>postback, the new elements are lost. I'm not sure how to tell ASP.Net to
>post back these new elements as well. Any ideas or sources where you
>could point me to will be greatly appreciated. I am still using ASP.Net
>1.1.
>>
>This is part of the code I am using to dynamically add the element:
>>
>myOpenerListCt rl.options[myOpenerListCtr l.options.lengt h] = new Option(
>districtName , districtID );
>>
>I also tried using standard DOM syntax:
>>
>var newOption = document.create Element( "option" );
>newOption.setA ttribute( "value", districtID );
>newOption.inne rText = districtName;
>myOpenerListCt rl.appendChild( newOption )
>>
>But neither is kept in the postback.
>>
>Thanks!
>>
>Mario
>>

>

[Laurent Bugnion, MVP]

Re: Options added to select list with JavaScript lost on postback

Hi,

Mario Vargas wrote:

Thanks, Steve! I also thought about this approach, but was hoping for a
better way...
>
Mario

To be fair, it's not ASP.NET which is guilty here, but the fact that the
items of a SELECT element are not transmitted on postback, but only the
selected value. Which makes sense, if you think of it, or else the
requests could be huge (think of these SELECT with the list of all
countries, for example).

Greetings,
Laurent
--
Laurent Bugnion [MVP ASP.NET]
Software engineering, Blog: http://www.galasoft.ch
PhotoAlbum: http://www.galasoft.ch/pictures
Support children in Calcutta: http://www.calcutta-espoir.ch

[Mario Vargas]

Re: Options added to select list with JavaScript lost on postback

Hi Laurent,

That's a very good point and something I didn't know about. Thanks for
sharing!

Mario

"Laurent Bugnion, MVP" <galasoft-lb@bluewin.chwr ote in message
news:uu4aA3JtHH A.4916@TK2MSFTN GP05.phx.gbl...

Hi,
>
Mario Vargas wrote:

>Thanks, Steve! I also thought about this approach, but was hoping for a
>better way...
>>
>Mario

>
To be fair, it's not ASP.NET which is guilty here, but the fact that the
items of a SELECT element are not transmitted on postback, but only the
selected value. Which makes sense, if you think of it, or else the
requests could be huge (think of these SELECT with the list of all
countries, for example).
>
Greetings,
Laurent
--
Laurent Bugnion [MVP ASP.NET]
Software engineering, Blog: http://www.galasoft.ch
PhotoAlbum: http://www.galasoft.ch/pictures
Support children in Calcutta: http://www.calcutta-espoir.ch