Add an additional label control to an <ItemTemplate> dynamically in certain cases - asp.net

Question

How can I add an extra label control dynamically (should be added only on certain conditions).
I am trying to do something like this:
<asp:DataGrid id="dg" runat="server" AutoGenerateColumns="false">
<Columns>
<asp:TemplateColumn SortExpression="Column1">
<HeaderTemplate>
<asp:LinkButton Runat="server" text="Column1 Hdr" ID="col1Hdr">
</asp:LinkButton>
</HeaderTemplate>
<ItemTemplate>
<asp:Label ID="col1Label" runat="server" Text='<%# Method1(DataBinder.Eval(Container.DataItem, "Column1").ToString(), DataBinder.Eval(Container.DataItem, "Column2").ToString()) %>' >
<asp:PlaceHolder ID="col2Holder" runat="server"></asp:PlaceHolder>
</asp:Label>
</ItemTemplate>
</asp:TemplateColumn>
</Columns>
</asp:DataGrid>
Alternatively, I tried putting the placeholder in a seperate template:
<EditItemTemplate>
<asp:PlaceHolder ID="col2Holder" runat="server"></asp:PlaceHolder>
</EditItemTemplate>
but to no avail.
Any tips on how I can create the Placeholder only in some cases (like for some values of Column1/Column2), rather than opt for a repeater approach...
I get a null reference exception but that was solved when I had to explicitly mention:
protected PlaceHolder col2Holder = new Placeholder();
instead of
protected PlaceHolder col2Holder;
But though method1 is able to set the 'Column1's text value correctly, it does nothing for the Column2's value...
Is there something I'm missing or is there a different way to do this?
Here's method1's defn:
public string Method1(string col1, string col2)
{
col1 += "Called method1";
Label col2label= new Label();
col2label.Visible = true;
col2label.Text = col2;
col2Holder.Controls.Add(col2label);
col2Holder.DataBind();
return col1;
}

Answer 1

Where and when do you need the extra control to be inserted?
You should most likely hookup a method to the OnItemDataBound event and in there decide whether to add a control or not. The event gives you a reference to the item being bound so you can say e.Item.Controls.Add(your_control)
Update
Ah, now i get it what you're asking for. You need to add another argument to your Method1 that takes a DataGridItem. When you call Method1 you add it like this Method1(Container) where Container refers to the DataGridItem in question. Then you can say in the Method1
public string Method1(DataGridItem item)
{
string col1 = DataBinder.Eval(item.DataItem, "Column1").ToString();
string col2 = DataBinder.Eval(item.DataItem, "Column2").ToString();
var col2label = new Label() { Visible = true, Text = col2 };
var col2Holder = item.FindControl("col2Holder");
col2Holder.Controls.Add(col2label);
return col1 + "Called method1";
}
Btw, you can't add any controls to a Label, your ItemTemplate should look like this
<ItemTemplate>
<asp:Label ID="col1Label" runat="server" Text="<%# Method1(Container) %>" />
<asp:PlaceHolder ID="col2Holder" runat="server" />
</ItemTemplate>
If you want the new Label to be nested inside the first label, you should do that explicit in the method, and leave out the placeholder:
<ItemTemplate>
<asp:Label ID="label" runat="server" Text="<%# Method1(Container) %>" />
</ItemTemplate>
public string Method1(DataGridItem item)
{
string col1 = DataBinder.Eval(item.DataItem, "Column1").ToString();
string col2 = DataBinder.Eval(item.DataItem, "Column2").ToString();
var label = item.FindControl("label");
var col2label = new Label() { Visible = true, Text = col2 };
col1Holder.Controls.Add(col2label);
return col1 + "Called method1";
}