Dynamic creation of Button OK but its event handler NOT executed? - asp.net

Question

I have following simple controls on a page
WebForm1.aspx
<asp:Panel ID="Panel1" runat="server">
</asp:Panel>
<br />
<asp:Label ID="lblContent" runat="server" ></asp:Label>
Some code behind in WebForm1.aspx.cs :
protected void Page_Load(object sender, EventArgs e)
{
Button btn = new Button();
btn.ID = "btnTest";
btn.Text = "I was dynamically created";
btn.Click += new EventHandler(btnTest_Click);
Panel1.Controls.Add(btn);
}
void btnTest_Click(object sender, EventArgs e)
{
lblContent.Text = "btnTest_Click: " + DateTime.Now.ToString();
}
In short, when I dynamically create a Button (btnTest) in the Page_Load event and assign event handler btnTest_Click to the button. Click event then, when loading the page I see btnTest appearing and when clicking on it the event handler btnTest_Click is invoked. OK, No problem.
I have a problem though when I try following scenario... first, I add a button to the page in designer mode.
<asp:Panel ID="Panel1" runat="server">
</asp:Panel>
<asp:Button ID="btnCreateDynamically" runat="server"
Text="Create Button Dynamically"
onclick="btnCreateDynamically_Click" />
<br />
<asp:Label ID="lblContent" runat="server" ></asp:Label>
I move the code from Page_Load to the button event handler of btnCreateDynamically as follows
protected void btnCreateDynamically_Click(object sender, EventArgs e)
{
Button btn = new Button();
btn.ID = "btnTest";
btn.Text = "I was dynamically created";
btn.Click += new EventHandler(btnTest_Click);
Panel1.Controls.Add(btn);
}
When running the WebApp now and clicking on btnCreateDynamically, btnTest is created but when I click on btnTest its event handler is NOT invoked ???
Why not?
How can I make this work?

Answer 1

You should add the dynamic controls in the Page's Init event handler so that the ViewState and Events are triggered appropriately.
Try doing this:
protected void Page_Init(object sender, EventArgs e)
{
Button btn = new Button();
btn.ID = "btnTest";
btn.Text = "I was dynamically created";
btn.Click += new EventHandler(btnTest_Click);
Panel1.Controls.Add(btn);
}

Answer 2

You need to re-create dynamic control on each postback, see my previous answer to a similar question here