Dumb it down for one who's basically a beginner
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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" %>
Category:
Subcategory: -
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" %>
Category:
Subcategory:Your issue might be related to the page lifecycle and the way ASP.NET handles postbacks. The key part of your issue is likely in your 'Page_Load' method where you are clearing and populating the dropdown list only if it's not a postback. The 'Page_Load' event occurs before the 'Button1_Click' event, so when you click the button, the 'Page_Load' event is triggered again before the button click event, and the dropdowns are reinitialized, you can change the behaviour -
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
ddlCategory.Items.Add("FirstCat");
ddlCategory.Items.Add("SecondCat");
ddlCategory_SelectedIndexChanged(sender, e);
}
else
{
Label1.Text = "I posted back";
}
} -
Your issue might be related to the page lifecycle and the way ASP.NET handles postbacks. The key part of your issue is likely in your 'Page_Load' method where you are clearing and populating the dropdown list only if it's not a postback. The 'Page_Load' event occurs before the 'Button1_Click' event, so when you click the button, the 'Page_Load' event is triggered again before the button click event, and the dropdowns are reinitialized, you can change the behaviour -
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
ddlCategory.Items.Add("FirstCat");
ddlCategory.Items.Add("SecondCat");
ddlCategory_SelectedIndexChanged(sender, e);
}
else
{
Label1.Text = "I posted back";
}
}Thanks for the reply. So Page_Load always re-initializes controls every time it's invoked, and any postback always triggers Page_Load? If it's clearing and re-populating the dropdowns every time it posts back, how is it possible to code it in such a way that the SubCategory dropdown's values depend on the selected value of Category? Again, sorry if I'm not asking the right questions, I hope this makes sense. Thanks DTXCF
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Thanks for the reply. So Page_Load always re-initializes controls every time it's invoked, and any postback always triggers Page_Load? If it's clearing and re-populating the dropdowns every time it posts back, how is it possible to code it in such a way that the SubCategory dropdown's values depend on the selected value of Category? Again, sorry if I'm not asking the right questions, I hope this makes sense. Thanks DTXCF
Yes, the 'Page_Load' event is triggered on every request to the page, including postbacks. This means that any code within the 'Page_Load' method will execute during each page load, whether it's an initial request or a postback. You can try and use the 'SelectedIndexChanged' event of your Category dropdown 'ddlCategory' to dynamically populate the 'SubCategory' dropdown named 'ddlSubCategory'' based on the selected value of Category, similar to -
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
//Populate Category dropdown during the initial load...
ddlCategory.Items.Add("FirstCat");
ddlCategory.Items.Add("SecondCat");
ddlCategory_SelectedIndexChanged(sender, e); //Initial population of your SubCategory dropdown...
}
//You can optionally handle postback-specific logic here if needed...
}protected void ddlCategory_SelectedIndexChanged(object sender, EventArgs e)
{
//Populate SubCategory dropdown based on your selected value of Category...
string selectedCategory = ddlCategory.SelectedValue;//Add some logic to fetch and populate SubCategory items based on the selectedCategory... //Logic might be something like this... - ddlSubCategory.Items.Clear(); //Clear existing items... if (selectedCategory == "FirstCat") { ddlSubCategory.Items.Add("SubCat1A"); ddlSubCategory.Items.Add("SubCat1B"); } else if (selectedCategory == "SecondCat") { ddlSubCategory.Items.Add("SubCat2A"); ddlSubCategory.Items.Add("SubCat2B"); } //Add more conditions here as you see fit...}
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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" %>
Category:
Subcategory:The texture of open data, does commence, as dudgeon, of event driven.