unable to take value of Dynamic Created Label

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I use This Code at Aspx:

XML

<asp:Button ID="BtnAdd" runat="server" Text="Add" onclick="BtnAdd_Click"  />

       <asp:Button ID="BtnTake" runat="server" Text="TakeValue"
           onclick="BtnTake_Click"  />

       <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

       <asp:Panel ID="Panel1" runat="server">

       </asp:Panel>

And At aspx.cs:

protected void BtnAdd_Click(object sender, EventArgs e)
    {
        Label lbl = new Label();
        lbl.ID = "Lbl1";
        lbl.Text = "Arun";
        Panel1.Controls.Add(lbl);
    }
    protected void BtnTake_Click(object sender, EventArgs e)
    {
        string lblName = "Lbl1";
        //Label Lbl = Panel1.FindControl(lblName) as Label;
        Label Lbl = (Label)Panel1.FindControl(lblName);
        TextBox1.Text = Lbl.Text; 
    }

When i click add button i easily create one Dynamic label,

but when i click on second button(take value)

Then it generated An error: like this:

Object reference not set to an instance of an object.

when i try Break point then i see that After click on button 2,

Label Lbl = (Label)Panel1.FindControl(lblName);

lbl return Null:

So what can i do for taking that dynemic created lables values

Posted 7-Apr-13 23:59pm

Arun kumar Gauttam

Updated 8-Apr-13 1:48am

v2

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Deependra Khangarot · Accepted Answer · 2013-04-08T00:13:00

Solution 1

Hi Arun,

After second postback (BtnTake_Click), your dynamically added controls will be lost. so you should add them in page's init event not in first button's click event.

Don't forget to set autopostback property of dropdownlist to true.

Posted 8-Apr-13 0:13am

Deependra Khangarot

_Amy · Accepted Answer · 2013-04-08T01:59:00

Always create your dynamic control in Page_Init event (Read this[^] for a detailed information).
Change your CS. Try this:

C#

//Create the controls in this page event
protected void Page_Init(object sender, EventArgs e)
{
    Label lbl = new Label();
    lbl.ID = "Lbl1";
    lbl.Text = "Arun";
    lbl.Visible = false; //Hide the control
    Panel1.Controls.Add(lbl);
}

protected void BtnAdd_Click(object sender, EventArgs e)
{
     Label Lbl = (Label)Panel1.FindControl(lblName);
     if(lbl != null)
          lbl.Visible = true;//Show if need
}
protected void BtnTake_Click(object sender, EventArgs e)
{
    string lblName = "Lbl1";
    //Label Lbl = Panel1.FindControl(lblName) as Label;
    Label Lbl = (Label)Panel1.FindControl(Lbl1);
    TextBox1.Text = Lbl.Text; 
}

--Amit