How to create a date and time plot with TikZ and pgfplots

Question

What I want to achieve is a graph, which shows the working hours per day. Input should be the triple of date, arrival time and leaving time. The x-axis holds the dates and the y-axis shows the working time - maybe as a bar somehow. Following code works so far with dates in x-axis and floats in the y-axis.

\documentclass{standalone}
\usepackage{tikz}
\usepackage{pgfcalendar}
\usepackage{pgfplotstable}
\usetikzlibrary{pgfplots.dateplot}
\usepgfplotslibrary{dateplot}
% File content zeiten_float.dat
%   datum kommt geht
%   2016-01-04 6.30 16.10
%   2016-01-05 6.40 16.20
%   2016-01-07 6.20 16.30
%   2016-01-08 6.10 16.40
%   2016-01-11 6.30 16.50
%   2016-01-12 6.50 16.10
%   2016-01-13 6.40 16.20
%   2016-01-14 6.10 16.30
\begin{document}
    \begin{tikzpicture}
        \begin{axis}[
            date coordinates in=x,
            xticklabel={\day.\month.}
            ]
            \addplot table[x=datum,y=kommt] {zeiten_float.dat};
            \addplot table[x=datum,y=geht]  {zeiten_float.dat};
        \end{axis}
    \end{tikzpicture}
\end{document}

Now the code, which fails. The difference compared to the ybove code is that I replaced the floats with the natural time format (refer to the comment block in the code) and I added the line to convert this time format for the y-axis, but there is the bug.

\documentclass{standalone}
\usepackage{tikz}
\usepackage{pgfcalendar}
\usetikzlibrary{pgfplots.dateplot}
\usepgfplotslibrary{dateplot}
% File content zeiten.dat
%   datum kommt geht
%   2016-01-04 06:30 16:10
%   2016-01-05 06:40 16:20
%   2016-01-07 06:20 16:30
%   2016-01-08 06:10 16:40
%   2016-01-11 06:30 16:50
%   2016-01-12 06:50 16:10
%   2016-01-13 06:40 16:20
%   2016-01-14 06:10 16:30
\begin{document}
    \begin{tikzpicture}
        \begin{axis}[
            date coordinates in=x,
            xticklabel={\day.\month.},
            date coordinates in=y,
            yticklabel={\hour:\minute}
            ]
            \addplot table[x=datum,y=kommt] {zeiten.dat};
            \addplot table[x=datum,y=geht]  {zeiten.dat};
        \end{axis}
    \end{tikzpicture}
\end{document}

It results in the error messages:

Answer 1

First of all, about packages/libraries you loaded: both \usetikzlibrary{pgfplots.dateplot} and \usepgfplotslibrary{dateplot} loads tikzlibrarypgfplots.dateplot.code.tex, which then loads pgfcalendar.code.tex, which \usepackage{pgfcalendar} loads. And you need pgfplots, which pgfplotstable loads.

Anyway, dateplot expects "complete" time stamp. It likes 2016-01-04 06:30 but dislikes 06:30. So... we could just write our own! (The structure is basically copied from the definition of date coordinates in in tikzlibrarypgfplots.dateplot.code.tex)

\documentclass[tikz]{standalone}
\usepackage{filecontents,pgfplots}
\usepgfplotslibrary{dateplot}

\begin{filecontents}{zeiten.dat}
    datum kommt geht
    2016-01-04 06:30 16:10
    2016-01-05 06:40 16:20
    2016-01-07 06:20 16:30
    2016-01-08 06:10 16:40
    2016-01-11 06:30 16:50
    2016-01-12 06:50 16:10
    2016-01-13 06:40 16:20
    2016-01-14 06:10 16:30
\end{filecontents}

\def\pgfplotslibdateplothour:minutetofloat#1:#2.{
    \pgfmathparse{#1+#2/60}
}
\def\pgfplotslibdateplofloattothour:minute#1.{
    \pgfmathsetmacro\hour{int(floor(#1))}
    \pgfmathsetmacro\minute{int((#1-\hour)*60)}
    \ifnum\hour<10\edef\hour{0\hour}\fi
    \ifnum\minute<10\edef\minute{0\minute}\fi
}
\pgfplotsset{
    /pgfplots/time coordinates in/.code={%
        \pgfkeysdef{/pgfplots/#1 coord trafo}{%
            \pgfplotslibdateplothour:minutetofloat##1.
        }
        \pgfkeysdef{/pgfplots/#1 coord inv trafo}{
            \pgfplotslibdateplofloattothour:minute##1.
        }
    }
}
\begin{document}
    \begin{tikzpicture}
        \begin{axis}[
            date coordinates in=x,
            xticklabel={\day.\month.},
            time coordinates in=y,
            yticklabel={\hour:\minute}
            ]
            \addplot table[x=datum,y=kommt] {zeiten.dat};
            \addplot table[x=datum,y=geht]  {zeiten.dat};
        \end{axis}
    \end{tikzpicture}
\end{document}