Cross-references Showing Part Number

Question

Is there a way to make cross references write \part number like this?

Cf. above Part 1, Page 3.

I am currently using: \here{}\label{} and \footnote{Cf. \where{}. Page \pageref{}.}

So I need something that would check in which part the label is and than write the number of that part in the footnote.

Edit: I thought that is not important re \where and \here but I am adding code for that as requested.

\makeatletter
\newcount\here@undef
\newcommand{\here}[1]{%
  \@ifundefined{here@#1@undef}{}{\global\advance\here@undef by -1}%
  \global\@namedef{here@#1}{}%
}
\newcommand{\where}[1]{%
  \@ifundefined{here@#1}{%
    below%
    \@ifundefined{here@#1@undef}{%
      \global\@namedef{here@#1@undef}{}%
      \global\advance\here@undef by 1
    }{}%
  }{%
    above%
  }%
}
\AtEndDocument{%
  \ifnum\here@undef>0
    \GenericWarning{}{There were undefined above/below labels}%
  \fi}
\makeatother%

Answer 1

The package zref is made for such tasks: Extraction of label data, if the relevant \zlabel etc. commands are used.

In order to provide the correct information, a 'property' has to be stored, in this case the property is the part number which should be connected to the label.

The command \here stores the label with the given name using \zlabel@byprops and \there extracts the information later on.

Update Version with working hyperlinks:

 \documentclass{scrbook}

\usepackage[counter,user,hyperref]{zref}




\makeatletter
\AtBeginDocument{%
\@ifpackageloaded{hyperref}{%
}{
  \providecommand{\phantomsection}{}
  \providecommand{\hyperlink}[2]{#2}
}

\zref@newlist{partpage}
\zref@newprop*{partprop}[-1]{\number\value{part}}
\zref@addprops{partpage}{partprop,page,anchor} % page is defined by default!

\newcounter{herecntr}

\newcommand{\here}[1]{%
  \phantomsection% Needed for correct hyper links
  \zref@labelbyprops{#1}{partprop,page,anchor}%
}

\newcommand{\there}[1]{%
  Part \zref[partprop]{#1}, page \hyperlink{\zref@extract{#1}{anchor}}{\zpageref{#1}}
}
}
\makeatother


\usepackage{hyperref}


\usepackage{blindtext}

\begin{document}
Now, let us see\footnote{You will find in \there{firstref} some important information, but in \there{secondref} the information is much more important. Give it a try, but do not forget the stuff in \there{somethingdifferent}}


\part{My wonderful first part} 

\blindtext[6] firstref\here{firstref}

\part{My second and yet better part}

\blindtext[7] secondref\here{secondref}


\part{My third and yet even better part}

\blindtext[3] thirdref\here{thirdref}

\chapter{Foo}\here{somethingdifferent}

\blindtext[2]

\end{document}

Update With compressed references, i.e. the \there command does not print the part number if the reference is in the same part!

\documentclass{scrbook}

\usepackage[counter,user,hyperref]{zref}




\makeatletter
\AtBeginDocument{%
\@ifpackageloaded{hyperref}{%
}{
  \providecommand{\phantomsection}{}
  \providecommand{\hyperlink}[2]{#2}
}

\zref@newlist{partpage}
\zref@newprop*{partprop}[-1]{\number\value{part}}
\zref@addprops{partpage}{partprop,page,anchor} % page is defined by default!

%\newcounter{herecntr}

\newcommand{\here}[1]{%
  \phantomsection% Needed for correct hyper links
  \zref@labelbyprops{#1}{partprop,page,anchor}%
}

\newcommand{\there}[1]{%
  \ifnum\value{part}=\zref@extract{#1}{partprop}\relax% Check whether the current part counter value is the same as the extracted part property from the label
  page \hyperlink{\zref@extract{#1}{anchor}}{\zpageref{#1}}
  \else% No, it is not the same!
  Part \zref[partprop]{#1}, page \hyperlink{\zref@extract{#1}{anchor}}{\zpageref{#1}}%
  \fi
}
}
\makeatother


\usepackage{hyperref}

\usepackage{blindtext}

\begin{document}

\part{My wonderful first part} 

Now, let us see\footnote{You will find in \there{firstref} some important information, but in \there{secondref} the information is much more important. Give it a try, but do not forget the stuff in \there{somethingdifferent}}



\blindtext[6] firstref\here{firstref}

\part{My second and yet better part}

\blindtext[7] secondref\here{secondref}


\part{My third and yet even better part}

\blindtext[3] thirdref\here{thirdref}

\chapter{Foo}\here{somethingdifferent}

\blindtext[2]

\end{document}