%------------------------------------------------------------
\usepackage{navigator}
\embeddedfile{sourcecode}{\jobname.tex}
%------------------------------------------------------------

%------------------------------------------------------------
\usepackage{draftwatermark}
\SetWatermarkText{ENTWURF}
\SetWatermarkLightness{0.8}
\SetWatermarkScale{4}
%------------------------------------------------------------

 \usepackage{navigator}
 \embeddedfile{sourcecode}{\jobname.tex}

\makeatletter % We need to access some internal commands
\newcommand*{\IfDataT}[1]{% Create a macro taking one argument
  \ifx#1\empty
    \expandafter\@gobble % Empty input: ignore the next thing
  \else
    \ifx#1\DTLstringnull
      \expandafter\expandafter\expandafter
        \@gobble % NULL input: ignore the next thing
    \else
      \expandafter\expandafter\expandafter
        \@firstofone % Use the next thing unchanged
    \fi
  \fi
} 
\newcommand*{\IfDataTF}[1]{% Create a macro taking one argument
  \ifx#1\empty
    \expandafter\@secondoftwo % Empty value: use the False branch
  \else
    \ifx#1\DTLstringnull
      \expandafter\expandafter\expandafter
        \@secondoftwo % NULL value: use the False branch
    \else
      \expandafter\expandafter\expandafter
        \@firstoftwo % A real value: use the True branch
    \fi
  \fi
} 
\makeatother