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QuestionSelectedIndexChanged for DropDown not fired when first item selected Pin
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QuestionDumb it down for one who's basically a beginner Pin
DalTXColtsFan15-Nov-23 6:31
DalTXColtsFan15-Nov-23 6:31 
OK, I'll put this in as few words as possible, and please bear with me if I am not clear, I'm still relatively new to this stuff:

So my company has a website we roll out to our customers, and the developers provided a base class to the consultants to use to create custom web parts. The website has a "design mode" built into it where an admin can divide the page up into sections, and basically assign a custom web part to that section of the page. The ascx and dll for the web part obviously have to be on the IIS server where the website can "see" it. I'm not sure exactly how that works technologically, i.e. if it's a master page with individual pages or if it's like a div or whatever.

Anyway, I tried to create a simple webpart with two dropdowns, one of which depends on the other, and a button. The labels and dropdowns appear to be initializing correctly. When I click the button, it correctly updates the label but it clears the dropdowns. Changing the selection in either dropdown appears to re-initialize the entire form including clearing the dropdowns.

Lastly, I could be wrong but I don't believe that the code in ddlCategory_SelectedIndexChanged is getting fired as a result of the dropdown getting clicked - I think it's only getting ran when I call it explicitly. Again, I could be wrong, but I feel like any time a "postback" is issued, only Page_Load is getting fired off, and the controls are all getting cleared/initialized before any of the code in Page_Load is actually run.

I'll pause there for a moment - does anyone see anything in *my* code that could be causing this incorrect result? Before I talk about how I could troubleshoot it within the framework of the rest of my company's website let's establish that.

Thanks
DTXCF

<%@ Control Language="C#" AutoEventWireup="true" CodeBehind="First2023WebUserControl.ascx.cs" Inherits="First2023Control.UserControls.First2023WebUserControl" %>
<asp:Label ID="Label1" runat="server" Text="Hello Year 2023"></asp:Label>
<p>
     </p>
Category:<asp:DropDownList ID="ddlCategory" runat="server" AutoPostBack="True" OnSelectedIndexChanged="ddlCategory_SelectedIndexChanged">
</asp:DropDownList>
<p>
    Subcategory:
    <asp:DropDownList ID="ddlSubcategory" runat="server" AutoPostBack="True">
    </asp:DropDownList>
</p>
<p>
    <asp:Label ID="Label2" runat="server" Text="Label"></asp:Label>
</p>
<asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="Button" />
<asp:Label ID="Label3" runat="server" Text="Label"></asp:Label>



using System;
using System.Collections.Generic;
using System.Data;
using System.Data.Common;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using Custom1.Custom2.Web.Framework;

namespace First2023Control.UserControls
{
//public partial class First2023WebUserControl : System.Web.UI.UserControl
public partial class First2023WebUserControl : Custom1.Custom2.Web.Framework.UserControlBase
{
[Property(DisplayName = "Message Text")]
public string MessageText
{
get
{
return Label1.Text;
}
set
{
Label1.Text = value;
}
}
protected void Page_Load(object sender, EventArgs e)
{

if (IsPostBack == false)
{
ddlCategory.Items.Add("FirstCat");
ddlCategory.Items.Add("SecondCat");
ddlCategory_SelectedIndexChanged(sender, e);
}
else
{
Label1.Text = "I posted back";
}
}

protected void ddlCategory_SelectedIndexChanged(object sender, EventArgs e)
{
Label2.Text = "The selected index changed";
if (ddlCategory.SelectedValue == "FirstCat")
{
ddlSubcategory.Items.Clear();
ddlSubcategory.Items.Add("FirstCatFirstSubCat");
ddlSubcategory.Items.Add("FirstCatSecondSubCat");
}
else
{
ddlSubcategory.Items.Clear();
ddlSubcategory.Items.Add("SecondCatFirstSubCat");
ddlSubcategory.Items.Add("SecondCatSecondSubCat");
}

}

protected void Button1_Click(object sender, EventArgs e)
{
Label3.Text = "Someone clicked the button";
}
}
}
AnswerRe: Dumb it down for one who's basically a beginner Pin
Andre Oosthuizen15-Nov-23 8:25
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GeneralRe: Dumb it down for one who's basically a beginner Pin
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GeneralRe: Dumb it down for one who's basically a beginner Pin
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Questioncan't build blazor library in azure pipeline Pin
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