Using xwatermark with pageref

Question

If I specify the option page of \newwatermark using \pageref, I get the following error:

Package xwatermark Error: No page specifier for watermark:

How to fix that?

\documentclass{article}
\usepackage{afterpage}
\usepackage{xwatermark} %[printwatermark]{xwatermark}
\usepackage{pdfpages}

\begin{document}

\verb|\pageref{sec:foo}| \pageref{sec:foo}  % 3, as expected

\newwatermark*[
% TODO replace
page=3
% by:
% \pageref{sec:foo} %  Package xwatermark Error: No page specifier for watermark:
]{Watermark}

\tableofcontents

\clearpage

\vspace*{\fill}
{\LARGE \begin{center}Bar\end{center}}
\vspace*{\fill}

\clearpage

\csname phantomsection \endcsname % hyperref
%\afterpage{
  \addcontentsline{toc}{section}{Foo}
%}
\label{sec:foo}
\includepdf[pages={1-}]{/home/er/Documents/essential/dev/LaTeX/toy/misc/huge/Foo.pdf} % Foo.pdf is a one page pdf


\end{document}

Answer 1

\pageref doesn't give a number, it only prints one. You can use the refcount package:

\documentclass{article}

\usepackage{xwatermark} %[printwatermark]{xwatermark}
\usepackage{pdfpages}
\usepackage{refcount}
\begin{document}

\verb|\pageref{sec:foo}| \pageref{sec:foo}  % 3, as expected

\newwatermark*[
page=\getpagerefnumber{sec:foo}
]{Watermark}

\newpage

\section{blub}\label{sec:foo}

\end{document}