Kentico 7 create content placeholder in Portal Master to use in ASCX in inherited page - ascx

Question

Working in Kentico 7 on an Ad-Hoc page that inherits from Portal Master. I want to insert some literal script or code right before the </body> tag in the rendered ad-hoc page.
I thought I'd have to do this by editing the portal master and adding the following:
<cms:CMSPagePlaceholder ID="plcBodyEnd" runat="server">
<LayoutTemplate>
</LayoutTemplate>
</cms:CMSPagePlaceholder>
and then in the layout of the Ad-Hoc page do this:
<cms:CMSContent runat="server" id="cntLeft" PagePlaceholderID="plcBodyEnd">
<script type="text/javascript">
ProviderConnections.Transparency.initializeWidget({ });
</script>
</cms:CMSContent>
This worked fine until I went to the design tab on the Ad-Hoc page, where I got the following error:
Object reference not set to an instance of an object.
I don't want to register script blocks. I just want to put text in the Ad-Hoc page that goes there before the </body> tag, which is controlled by Portal Master.
What am I doing wrong?

Answer 1

I'm not 100% sure what you are trying to achieve. Giving an example or attaching a screenshot would be very helpful.
Here are the ways of attaching JavaScript in Kentico:
Through portal engine:
Use JavaScript web part - that gives you an option of choosing where the script should be located
Programmatically from code-behind:
Use CMS.Helpers.ScriptHelper API (wrapper around ASP.NET's ClientScriptManager)
ScriptHelper.RegisterStartupScript() to put the script at the end of the page
ScriptHelper.RegisterClientScriptBlock() to put the script before page's elements
The difference between the two is well explained here.
Programmatically from ASPX markup:
Put your <script> block to a desired location in your .aspx / .ascx files
Evaluate a code-behind variable containing script
<asp:Button ID="btnOK" runat="server" Text="OK" />
<script type="text/javascript">
<%= fieldWithActualScript %>
</script>