Loading a listbox from a Dropdownlist

G

gv

Ok,

Hi all, new to asp.net. Simple question

with web forms

I have a Dropdownlist and a listbox, I want to click on and item in the
dropdownlist and show items in listbox. that simple

I have this: I have two items in Dropdownlist. The Reportlist doesn't show
the items ?

I tried to set the Autopostback to true. This does work but, the page
flickers

Private Sub Databaselist_SelectedIndexChanged(ByVal sender As
System.Object, ByVal e As System.EventArgs) Handles
Databaselist.SelectedIndexChanged
If Databaselist.SelectedValue = "Test1" Then

ReportList.Items.Clear()
ReportList.Items.Add("Test1Totals by Date Range")
ReportList.Items.Add("Test1Totals by name and Date Range")

ElseIf Databaselist.SelectedValue = "Test2" Then

ReportList.Items.Clear()
ReportList.Items.Add("Test2Totals by Date Range")
ReportList.Items.Add("Test2 Totals by name and Date Range")

End If
End Sub
 
C

Curt_C [MVP]

are you clearing them/setting them in the page_load? You may be blanking
them out each time.
look at the IsPostBack() to differentiate
 
G

gv

Thanks for your help, I'm only clearing the listbox before I load the new
values based on what is selected in the dropdownlist.
The values load fine when the page first opens. Not when the
controls SelectedIndexChanged event fires.

GV
 
K

Karl Seguin

Gv:
It works fine for me. Are you sure you have the AutoPostBack=true for the
dropdownlist?

karl
 
G

gv

If I do that, it works fine like I said but, flickers?

I don't want it to flicker when I do this.

thanks
gv
 
K

Karl Seguin

Geez..so much for reading through everything....i didn't catch that at all.

One solution is to do everything on the client-side...which has its up and
down side.

Another one is to turn on SmartNavigation which only works in IE and some
people have a lot of problems with it. Try putting SmartNaviation=true in
the <%@ Page directive...
You should check out:
http://weblogs.asp.net/ksamaschke/archive/2003/04/27/6085.aspx or just do a
google search for SmartNavigation

Other that that, it's the nature of doing web programming...

Karl
 
C

Curt_C [MVP]

you cant avoid the flicker. That is the page making a round trip to the
server, its unavoidable unless you do it all with clientside code
 
K

Karl Seguin

GV:
There's no magic bullet to achieve this...it involves knowing a lot about
javascript, cross browser issues and using whatever ASP.Net offers to make
it easier (which really isn't too much, sadly).

One slightly clean solution is outlined here:
http://www.15seconds.com/issue/010205.htm

hope this sends you in the right direction.

Karl
 

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