Where did my Dynamic Controls go?

Hi everyone. I am currently trying to do my best to learn ASP.NET /C#. I am working on trying to understand dynamic controls,post backs, and view states. I have read so many articles and I can not get past what seems to be a very simple problem. Here is the scenario. A user picks a value from the drop down list. Once the user picks an item, Im assuming the autopostback=true enables the OnTextChanged event to be fired were I create two dynamic controls 1 radiobuttonlist and 1 label. The user checks a radio value and the submit button is fired. On this event im trying to findcontrol and output to the screen. In reality I want to capture the result and store it in a DB. However when I try and find the radio_1 control on submission I am not able to find the control and out put it to the screen. On the other hand if i look for "dropdownlist 1" I can locate the static control with out any problems. I believe this issue is realated to viewstate and postbacks but i cant find any real examples. This kind of scenerio seems it would be a very common senerio in page development yet there is really no good source of examples. Can anyone please help me understand what needs to be added to the code to make this work? Thank you in advance. The code is as follows.


<head runat="server">
    <title>Untitled Pagetitle>
head>
<body>
    <form id="form1" runat="server">
        
    <div>
        <asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True" DataSourceID="QaQuestions"
            DataTextField="Role_Name" DataValueField="Role_ID" OnTextChanged="get_question">
        asp:DropDownList><asp:SqlDataSource ID="QaQuestions" runat="server" ConnectionString="<%$ ConnectionStrings:QAquestionConnectionString %>"
            SelectCommand="SELECT [Role_Name], [Role_ID] FROM [Role]">asp:SqlDataSource>
         
        <asp:Panel ID="Panel1" runat="server" Height="50px" Width="500px">
        asp:Panel>
        <asp:button ID="Button1" runat="server" text="Submit" OnClick="Button1_Click" />
        div>
    form>
body>

html>

The c# code

 protected void Page_Load(object sender, EventArgs e)
    {

    }

    protected void get_question(object sender, EventArgs e)
    {
        Label question = new Label();
        question.Text = "how do you like your job?";
        Panel1.Controls.Add(question);

        RadioButtonList radio = new RadioButtonList();
        radio.ID = "radio_1";
        radio.RepeatDirection = RepeatDirection.Horizontal;
        radio.Items.Add(new ListItem("Yes","1"));
        radio.Items.Add(new ListItem("No","2"));
        radio.Items.Add(new ListItem("N/A","3"));

        Panel1.Controls.Add(radio);
    }
    

   protected void  Button1_Click(object sender, EventArgs e)
{
    // Find control on page.
    Control myControl1 = FindControl("radio_1");
    if (myControl1 != null)
    {
        // Get control's parent.
        Control myControl2 = myControl1.Parent;
        
        Response.Write("Parent of the text box is : " + myControl2.ID);
    }
    else
    {
        Response.Write("Control not found");
    }

hey Tomasz Motyka
as u r learning asp.net and read about postback and page life cycle i suggest u to give more time on learning fundamental concepts

actually the basic problem in ur code as far as i know is dynamic control is added on textchanged event
but remember when u will get text changed event just put a breakpoint in form's load event
and u get that when page is postbacked. so now the control is on page

but what again happen when u click on button which also required post back and ur radio will be lost this time then how u can get it ??

hope u understand the thing

so add radio in page and set its style display as none and this will no longer is visible on page now on text changed just set display to not none and u get radio for user to select radio values now on button click u can get values

hope this will help u

akhil

2 Replies

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akhil17y ago
hey Tomasz Motyka
as u r learning asp.net and read about postback and page life cycle i suggest u to give more time on learning fundamental concepts

actually the basic problem in ur code as far as i know is dynamic control is added on textchanged event
but remember when u will get text changed event just put a breakpoint in form's load event
and u get that when page is postbacked. so now the control is on page

but what again happen when u click on button which also required post back and ur radio will be lost this time then how u can get it ??

hope u understand the thing

so add radio in page and set its style display as none and this will no longer is visible on page now on text changed just set display to not none and u get radio for user to select radio values now on button click u can get values

hope this will help u

akhil
0
Bechir Bejaoui17y ago
Before taking any step, I invite you to read this article

http://msdn.microsoft.com/en-us/library/1whwt1k7.aspx

I think some issues will be clear in your mind a s a beginner after reading this article
0