Your help needed, been on this issue for too long!

ysfkay · July 11th, 2010, 05:59 PM

I have a web form, by the left side of the webform is a menu control, when the menu control is clicked, a usercontrol is dynamically loaded. This usercontrol has two ListBoxes, when an item in the first ListBox is slected, the selected index changed event is fired, which executes code to load values into the second ListBox.That is to say, the values that should be in the second ListBox depend on the selected index of the first ListBox.That workd fine, but the problem comes in when I submit the form, I noticed that the record was not inserted into the database. I traced it to the second ListBox, this is what happens, whatever index I select in the second ListBox, when I click the submit button, the selectedIndex is set to -1 I have been trying to solve this for days, I had to abandon for a while. someone told me that this is happening becos I did not load the second ListBox at page Load so the selectedvalu is lost at postback. Yes I do not Load the second ListBox at page Load becus its content should depend on the selected index of the first Listbox, both controls are on a dynamically loaded usercontrol. Will appreciate any help, thanks...

avrail · July 11th, 2010, 06:09 PM

hay,
please be a ware that, every time your listbox will be regenerated from the beginning that because you've created it at the page load event,
you need to add your list box definition iniside

Code:

if(!IsPostBack) { //then add your listbox definition here }

ysfkay · July 11th, 2010, 07:00 PM

Please can you come clear, I need a better explanation. And yes I noticed before now that if I load the List box inside the "if(!IsPostBack)" it doesnt get loaded, maybe its cuz am working on a dynamically loaded usercontrol and not directly on a web form, am not sure, but thats what happens, so what I do is that I load it in the pageLoad and then use the Clear() method to clear its values before loading whenever a post back occurs, however, that is for the first list box, I load the second ListBox when the selectedIndex changed of the second ListBox is fired. Please see code below

//This is the page_Load of a dynamically loaded user control
protected void Page_Load(object sender, EventArgs e)
{

LoadBlocks();//Loads First ListBox

if (!IsPostBack)
{
//If I put the LoadBlocks() here,the ListBox doesnt get loaded
}

}

//LoadBlocks method
protected void LoadBlocks()
{
ListBoxBlocks.Items.Clear();

foreach (var i in ControlLoader.GetBlocks())
{

ListBoxBlocks.Items.Add(i.BlockNumber.ToString());

}

}

//Selected Index of LoadBlocks which Loads the Second ListBox called //ListBoxShops

protected void ListBoxBlocks_SelectedIndexChanged(object sender, EventArgs e)
{
ListBoxShops.Items.Clear();
GetAvailableShops(lstBlocksKeys.ElementAt(ListBoxB locks.SelectedIndex));

foreach (var i in ControlLoader.GetAvailableShops(lstBlocks.ElementA t(ListBoxBlocks.SelectedIndex)))
{

ListBoxShops.Items.Add(i.ShopNumber.ToString());
}

}

avrail · July 11th, 2010, 07:55 PM

hay,
actually your LoadBlocks should be loaded, there is something still missing,
at least the first time you visit your page load this is (!IsPostBack)
so it should be loaded

ysfkay · July 11th, 2010, 08:34 PM

I appreciate the help, but the problem isnt solved

avrail · July 11th, 2010, 08:58 PM

hay,
I understand that this is not solving your issue,
so i made a little sample, if it doesn't help then i will ask for more codes,

this is my first markup file, it contains 2 list boxes one of them are advisable

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="WebApplication1.WebForm1" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>Untitled Page</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:ListBox ID="ListBoxBlocks" runat="server" AutoPostBack="True"
onselectedindexchanged="ListBoxBlocks_SelectedInde xChanged" Width="225px"></asp:ListBox>

<asp:ListBox ID="ListBoxShops" runat="server" Visible="False" Width="373px"></asp:ListBox>
</div>
</form>
</body>
</html>

and the second one is the code file .cs

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;

namespace WebApplication1
{
public partial class WebForm1 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
LoadBlocks();
}
}

protected void LoadBlocks()
{
ListBoxBlocks.Items.Clear();
string str = "Just a Demo";
foreach (var i in str.ToCharArray())
{
ListBoxBlocks.Items.Add(i.ToString());
}
}

protected void ListBoxBlocks_SelectedIndexChanged(object sender, EventArgs e)
{
ListBoxShops.Items.Clear();
//GetAvailableShops(lstBlocksKeys.ElementAt(ListBoxB locks.SelectedIndex));
string str = "Just a Demo";
int indexSelected = ListBoxBlocks.SelectedIndex;
char[] myList = str.ToCharArray();
//foreach (var i in ControlLoader.GetAvailableShops(lstBlocks.ElementA t(ListBoxBlocks.SelectedIndex)))
//{
ListBoxShops.Items.Add(myList[indexSelected].ToString());
//}
ListBoxShops.Visible = true;
}
}
}

try to check them

ysfkay · July 12th, 2010, 01:28 AM

I tried it that way,but when I put the LoadBlocks inside (!IsPostBack) then
it does not get populated, please also be reminded that my ListBoxes are not directly on a webform, they are childs of a dynamically loaded usercontrol as I explained above, my main problem is why I get the selectedIndex of ListBoxShops set to -1 when I click on the submit button...Thanks alot.