Listbox only posts data for selected items

[BillAtWork]

Hi,
I have a listbox (in a user control) which has items add/removed via
javascript (i.e. an "add item" link which uses a popup selection screen to
add items and a "remove item" link which deletes any selected row(s)).

There is a strange problem that when I inspect the list of items during a
postback the list appears to be empty (even though I added items). I noticed
that when I multiselect one or more items, only those selected items are
posted back!

What the heck is going on?! I'm not doing any other processing that may be
related to this problem.

Thanks

[Walter Wang [MSFT]]

Hi,

It's because using client-side code, the ViewState cannot be modified, so
when the ListBox is rebuilt on postback, it won't have the information in
the ViewState about the new items.

A workaround is: when adding the items client-side, also save the info to a
hidden input field. In Page_Load, get the information from the hidden input
field and add the items. This will put it into the ViewState.

For a complete working sample, you can refer to following URL:

http://metabuilders.com/Tools/DynamicListBox.aspx

It contains a ASP.NET 1.1 custom control DynamicListBox which can add items
at client-side using javascript and still retain them on postback.

I hope this helps. Please feel free to post here if anything is unclear.

Sincerely,
Walter Wang (wa****@online. microsoft.com, remove 'online.')
Microsoft Online Community Support

=============== =============== =============== =====
Get notification to my posts through email? Please refer to
http://msdn.microsoft.com/subscripti...ult.aspx#notif
ications.

Note: The MSDN Managed Newsgroup support offering is for non-urgent issues
where an initial response from the community or a Microsoft Support
Engineer within 1 business day is acceptable. Please note that each follow
up response may take approximately 2 business days as the support
professional working with you may need further investigation to reach the
most efficient resolution. The offering is not appropriate for situations
that require urgent, real-time or phone-based interactions or complex
project analysis and dump analysis issues. Issues of this nature are best
handled working with a dedicated Microsoft Support Engineer by contacting
Microsoft Customer Support Services (CSS) at
http://msdn.microsoft.com/subscripti...t/default.aspx.
=============== =============== =============== =====

This posting is provided "AS IS" with no warranties, and confers no rights.