Detecting if controls exist in a control collection

Question

UPDATE: Apologies on lack of clarity I realise I could iterate over the controls collection, was just looking for a better/more efficient method.

I am trying to dynamically add some css and js elements into an ASP.Net page at runtime, but because this code is used in mutliple controls I need to ensure that the relevant links are only injected once.

Currently I have the folowing code in the OnPreRender event.

Dim head As HtmlControls.HtmlHead = Me.Parent.Page.Header

If Not _useCustomStyles Then

    Dim litCustomCss As New LiteralControl("<link rel=" & Chr(34) & "stylesheet" & Chr(34) & " href=" & Chr(34) & "/css/udPart_core.css" & Chr(34) & " type=" & Chr(34) & "text/css" & Chr(34) & " media=" & Chr(34) & "screen" & Chr(34) & " />" & vbCrLf)

    litCustomCss.ID = "cssCustom"

    If Not head.Controls.Contains(litCustomCss) Then
        head.Controls.Add(litCustomCss)
    End If

End If

Does .Contains look for this instance of an object (which I assume is why this is failing)?

Is there a way to check the controls collection for a specific id? Or am I going to have to write a sub to loop through the existing controls in the collection checking for the id.

Thanks

Answer 1

For external script sources you can use this :

if (!ClientScript.IsClientScriptIncludeRegistered("externalResuorce"))
{
    ClientScript.RegisterClientScriptInclude("externalResuorce", 
    "scripts/myscripts.js");
}

But for stylesheet files, you can use this :

HtmlLink link = new HtmlLink();
link.Href = "main.css";
link.Attributes["type"] = "text/css";
link.Attributes["rel"] = "stylesheet";
Page.Header.Controls.Add(link);

and to control maybe you should loop Page.Header.Controls collection and look for a HtmlLink that has main.css href.

EDIT : Also this might help for finding your literal control in header's controls collection :

Page.Header.FindControl("your_literals_id");