Dynamically adding a commandbutton in ASP.NET

Question

I have a page with a dynamically created command button.

I need to dynamically wire up a click event so I can grab the CommandArgument of the clicked button.

Button b = new Button(); b.ID = "btnTrigger2"; b.CssClass = "hiddenBtn"; b.CommandName = "lbl3"; b.Click += new EventHandler(btnTrigger_Click);

The problem is the last line - I can't wire up an EventHandler this way - I need to use the standard EventArgs instead of CommandEventArgs.

Anyone have any suggestions on getting this to work? There's got to be a way...

EDIT

Figured I'd post the code that finally worked in case anyone else tries to do the same thing.

`string tabLoadedScript = string.Empty; string postBackScript = string.Empty;

string script = " <script language='javascript' type='text/javascript'>" + System.Environment.NewLine; script += "function clientActiveTabChanged(sender, args) {" + System.Environment.NewLine; int i = 0; foreach(TabPanel tp in tc1.Tabs) { Button b = new Button(); b.ID = "btn" + tp.ClientID; b.CssClass = "hiddenBtn"; b.CommandName = tp.ID; b.Command += btnTrigger_Click; this.form1.Controls.Add(b); AsyncPostBackTrigger trg = new AsyncPostBackTrigger(); trg.ControlID = "btn" + tp.ClientID; tabLoadedScript += "var isTab" + tp.ClientID + "loaded=$get('" + tp.Controls[0].ClientID + "');" + System.Environment.NewLine; postBackScript += "if(!isTab" + tp.ClientID + "loaded && sender.get_activeTabIndex() == " + i + ") {" + System.Environment.NewLine; postBackScript += "__doPostBack('" + b.ClientID + "','');}" + System.Environment.NewLine; i++; } script += tabLoadedScript; script += postBackScript; script += "}" + System.Environment.NewLine; script += "</script>";

this.ClientScript.RegisterClientScriptBlock(this.GetType(), "cs", script, false);

protected void btnTrigger_Click(object sender, CommandEventArgs e) { System.Threading.Thread.Sleep(2500); Panel ctrl = (Panel) FindControlRecursive(this, "pnl" + e.CommandName); ctrl.Visible = true; }

public static Control FindControlRecursive(Control Root, string Id) { if(Root.ID == Id) return Root; foreach(Control Ctl in Root.Controls) { Control FoundCtl = FindControlRecursive(Ctl, Id); if(FoundCtl != null) return FoundCtl; } return null; }

`

Chandu · Accepted Answer · 2011-04-01 20:54:23Z

You can still access the CommandArgument using the the first argument passed to the click handler.

Something like:

protected void btnTrigger_Click(object sender, EventArgs e) { Button btnTrigger = sender as Button; String commandArgument = btnTrigger.CommandArgument; . . . . //Other code.... }

Jonas Høgh · Accepted Answer · 2011-04-01 21:08:21Z

You need to use the Command event instead of the Click event. Also, assuming you're using a recent version of Visual Studio and .Net, you can simply change the event registration from

b.Click += new EventHandler(btnTrigger_Click);

to

b.Command += btnTrigger_Click

The explicit typing of the delegate is redundant and will be inferred by the compiler. You can now change the signature of your event handler to:

protected void btnTrigger_Click(object sender, CommandEventArgs e)

And the code should work as desired.

Unfortunately, the default code snippets in Visual Studio still generate this old-style event listener code.

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