How can I respond to a click event from an HTML button server-side?

Question

I'm creating a button on a Sharepoint page dynamically (in C#) in my *.ascx.cs file:

Button btnSave = null;

protected void Page_Load(object sender, EventArgs e)
{
    base.OnPreRender(e);    

    this.Controls.Add(new LiteralControl("<br />"));
    btnSave = new Button();
    btnSave.ID = "btnSave";
    btnSave.Text = "Save the Data"; 
    btnSave.Click += new EventHandler(btnSave_Click);
    btnSave.Visible = false;
    this.Controls.Add(btnSave);
}

protected void btnSave_Click(object sender, EventArgs e)
{
    btnSave.Text = "You clicked me!"; 
    PostTravelData ptd = new PostTravelData();
}

I set it visible at the right time in the client-side jQuery in the *.ascx file:

$('#btnSave').show();

However, clicking the button does not reach the btnSave_Click() event - the breakpoint there is never reached, nor is the button's text changed. Why not?

Even when I don't set the button invisible (comment out the "btnSave.Visible = false;" line), the click handler isn't reached...is Page_Load() too late? Is there an earlier page event I can use that would work?

I tried moving it from Page_Load() to OnPreRender(), too, like this:

protected void OnPreRender(EventArgs e)
{
    this.Controls.Add(new LiteralControl("<br />"));
    btnSave = new Button();
    btnSave.ID = "btnSave";
    btnSave.Text = "Save the Data";
    btnSave.Click += new EventHandler(btnSave_Click);
    //btnSave.Visible = false;
    this.Controls.Add(btnSave);
}

...(and OnRender()) but the button doesn't even display...

And, trying a different tack, I commented out the dynamic creation server-side code and tried to attach to a button created in the HTML (*.ascx file):

<button type="button" name="saveData" id="saveData" runat="server" onclick="saveData_Click">Save Data</button>

(by adding the "runat server" and the onclick handler), and then adding this "code-behind" (*.ascx.cs)):

protected void saveData_Click(object sender, EventArgs e)
{
    PostTravelData ptd = new PostTravelData();
    SaveToList(ptd);
    GeneratePDF(ptd);
}        

...but there was still no joy in Mudville -- the breakpoint in the handler is not reached.

Yet another attempt was:

In the *.ascx:

<asp:Button runat="server" id="saveData" name="saveData" onclick="saveData_Click" Text="Bla" />

In the code-behind:

saveData.Click += saveData_Click;

The "Bla" button is created, but clicking on it reaches not the breakpoint in the "saveData_Click" handler.

I even adapted some code from here like so:

Button btnSave = null;

. . .

protected override void CreateChildControls()
{
    btnSave = new Button();
    btnSave.Width = new Unit(150, UnitType.Pixel);
    btnSave.Text = "Can you see me?";
    btnSave.Click += new EventHandler(btnSave_Click);
    Controls.Add(btnSave);
}

...but I still do not reach the "protected void btnSave_Click(object sender, EventArgs e)" handler when I click the button.

Surely there's a way to get a handle on the button server-side and manipulate it (specifically, respond to its click event)...?!?

Answer 1

For it to work (for the event to fire), the button has to be an HtmlButton (not a generic (submit) Button), and the ServerClick event needs to be assigned, (not the plain old Click event). This works:

protected void Page_Load(object sender, EventArgs e)
{
    base.OnPreRender(e);

    btnSave = new HtmlButton();
    btnSave.ID = "btnSave";
    btnSave.InnerHtml = "Save";
    btnSave.ServerClick += new EventHandler(btnSave_Click);
    this.Controls.Add(btnSave);
}

protected void btnSave_Click(object sender, EventArgs e)
{
}