Dynamically Loading User Control and Maintaining its viewstate. And Getting Values from the control.

 I have a drop down which is populated on the page looad.  When i select an item from drop downlist i get to see two listboxes with add/removing the objects from one left to right listbox and below that i have a user control which should be populated dynamically based on the selectedvalue from drop down list.  So there are three sections that are seen once a selected value is consiedered from drop down list.  Now I am getting the user control using the below code given

case "42": viewRequired = "vw_AncCostSavingsByCarrier_adhoc";
                Control CostSavingReportUserControl = (User_Controls_CostSavingReport)LoadControl("~/User Controls/CostSavingReport.ascx");
                ViewState["ReportTitle"] = "Non Pharmacy Cost Savings Report";

 Which is a switch case as i have n number of user controls.  But i am unable to get the values the user entered into that control on the button click event down that user control. And when user clicks and Add/Remove button to add/remove items from one to another this controls is going visible, So i have reloaded that user control once again.  But the questions is ia m unable to get the values entered into the user control.  What could be the best way in getting the values from the user control which is added dynamically.

What i want is getting the value from user control.  Secondly i dont want to register any user control in the aspx(if possible).  Above  code (User_Controls_CostSavingReport) is the user control i casted to which is not needed as control only needs the virtual path.  So i am able to load user control, and reloading if add/remove the buttons for selecting/removing items from listbox.  And finally user enters values which i need to get.  I want the values to remain in the user control even after the button click is done which actually needs these values from user control and generate a report in a new page.

 Any Kind of help would be greatly appreciated. 



9/22/2008 1:44:56 PM
asp.net.web-forms 93655 articles. 5 followers. Follow

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which event r you using ? some time you get value in page_prerender event. and It can be solved by adding custom event/delegate to user control. well can you post ur aspx.cs code?

Anuj Patel
If this post answers your question please mark it as Answered.
9/22/2008 2:57:36 PM

Asp.Net does not maintain the control tree, if you have programmatically added controls then you have to maintain them yourself. This means you have to add them to the control tree on every round trip.
All ViewState does is keep properties of your controls and reaplly them during round trips and this is based on control ID so be carefull to give the controls the same ID's.
Please create a simple example where you have a button that creates a textbox and in the click event after creating the textbox say something like: ViewState[<key>]=<value>; then in the page load event test if that key value pair exists and if the value is what it should be and recreate the textbox. Also add another button to test the value in that textbox, you'll see this solves the problem and the value is correctly displayed.

  TextBox txt=new TextBox();

    if((bool)ViewState["txtadded"] { button1_Click(button1, EventArgs.Empty); }

Let me know if this helps, if you have any trouble I can send you an working example to see what I'm talking about.


9/22/2008 3:02:45 PM

 can you please send me some working samples.  It could be of great help for me. 

situation is i have a user control for every report which should be loaded each time that report link is selected on the same page.  How i achieved this task is by hiding all the user controls in the design and setting the visibility to false.  And used delegates and event handlers to make the button click event of that user control and also the parametres to pass to aspx from that user control.  So i think my page size is going to increase if i go on and on.  So i just want to get rid of this situation.


Please send me if you have any samples.



10/1/2008 2:45:35 PM


1    <%@ Page Language="C#" AutoEventWireup="true"  CodeFile="Default.aspx.cs" Inherits="_Default" %>
3    <%@ Register Src="HeaderMenu.ascx" TagName="HeaderMenu" TagPrefix="uc1" %>
5    <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
7    <html xmlns="http://www.w3.org/1999/xhtml" >
8    <head runat="server">
9        <title>Untitled Page</title>
10   </head>
11   <body>
12       <form id="form1" runat="server">
13       <div>
14           <div id="div_Content" runat="server"></div>
15           <asp:Button ID="Button_Insert" runat="server" Text="Insert" OnClick="Button_Insert_Click" />
16           <asp:Button ID="Button_Read" runat="server" Text="Read Value" OnClick="Button_Read_Click" /><br />
17           <asp:Label ID="Label_Value" runat="server"></asp:Label>
18        </div>
19       </form>
20   </body>
21   </html>
1    using System;
2    using System.Data;
3    using System.Configuration;
4    using System.Web;
5    using System.Web.Security;
6    using System.Web.UI;
7    using System.Web.UI.WebControls;
8    using System.Web.UI.WebControls.WebParts;
9    using System.Web.UI.HtmlControls;
11   public partial class _Default : System.Web.UI.Page 
12   {
13       protected void Page_Load(object sender, EventArgs e)
14       {
22           if (ViewState["_txt"] != null)
23           {
24               if ((bool)ViewState["_txt"]) { Button_Insert_Click(Button_Insert, EventArgs.Empty); }
25           }
26       }
27       protected void Button_Insert_Click(object sender, EventArgs e)
28       {
29           div_Content.Controls.Add(new TextBox());
30           ViewState["_txt"] = true;
31       }
32       protected void Button_Read_Click(object sender, EventArgs e)
33       {
34           Label_Value.Text = ((TextBox)div_Content.Controls[0]).Text;
35       }
36   }
10/2/2008 6:54:15 AM

 Thank You doly for the information given.  Every user control has its own button in it.  So i load that user control in a drop downlist selected index changed event. (I show two list boxes with ability to transfer data from one listbox to other like add/remove buttons between those two listboxes and also under neath that i get the user control loaded.)  Now when the user hits on add or remove buttons he should be able to see the same user control and should not loose any data if he has entered into it.

 Now i want to raise the button click event for that user control (each user control has its own submit button.) and get its values in that click event.  Suggest me if i can use a common button for all the reports or keep that in the user control.  And how can i get the values in that user control.

Generally for single user control i can use the delegates and eventargs to pass the values of that user control.

 In the code sent by you you Viewstate for _txt is always null as it is in pageload event and it means that it will always be null.

Secondly i did not understand why you are using two buttons..hope you got my situation. Please let me know if you need anything from me..I am in real hard situation to do this.

 Any help would be greatly appreciated.



10/2/2008 10:17:16 PM

This is just a simple example of how I handle programmatically created controls, this makes theese controls behave just like declarative ones.
Please insert break points in that Page_Load event and you'll see that ViewState["_txt"] is not allways null. Basically what I'm doing there is checking to see if the control has been created and if it has been created then recreate it on every roundtrip.

I will try to create an example of what you are trying to do: a DropDownList that on SelectedIndexChanged event loads a user control that contains 2 ListBoxes and 2 buttons that can move Items from one to the other and a third submit button.
I will get back to you once I'm finished with this example.


10/3/2008 7:03:22 AM

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