Dynamic creation of Button OK but its event handler NOT executed?

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?

Chandu · Accepted Answer · 2011-04-01 21:28:55Z

2

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);     
}

answered Apr 1, 2011 at 21:28

Chandu

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1 Comment

LCJ Over a year ago

What if the controls are to be added on a click event as described in stackoverflow.com/questions/14338798/… ?

Community · Accepted Answer · 2017-05-23 12:14:13Z

1

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

edited May 23, 2017 at 12:14

CommunityBot

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answered Apr 1, 2011 at 21:32

Richard Friend

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