Cite a website with date

Question

I'm trying to create a website bibliography, but the urldate is not being shown, only the year when the website was last update.

\documentclass{article}

\usepackage[sorting=nyt,style=authoryear, backend=bibtex8]{biblatex}   
\addbibresource{Literatur} 

\DeclareCiteCommand{\parencite}
{\ifentrytype{online}{\bibopenparen}{\bibopenbracket}
\usebibmacro{prenote}}
{\usebibmacro{citeindex}
\usebibmacro{cite}}
{\multicitedelim}
{\usebibmacro{postnote}
\ifentrytype{online}{\bibcloseparen}{\bibclosebracket}}

\begin{filecontents}{\Literature.bib}
@online{Wikipedia.27.02.2017,
 author = {Wikipedia, the free encyclopedia},
 year = {2017},
 title = {MALDI-TOF},
 url = {https://de.wikipedia.org/wiki/MALDI-TOF},
 urldate = {02.06.2017}
}

\begin{document}

\parencite{Wikipedia.27.02.2017}

\newpage
\fancyhead[R]{\nouppercase{Internet Sources}}
\printbibliography[heading=bibintoc,title={ Internet Sources },type=online]

\end{document}

Answer 1

You need to specify the date in biblatex's date fields in a certain way. From the manual:

Date fields such as the default data model dates date, origdate, eventdate, and urldate adhere to EDTF (Extended Date/Time Format) specification levels 0 and 1.

This will most times mean yyyy-mm-dd, so in your case:

urldate={2017-06-02}