biblatex show urldate as full date

Question

I am trying to use biblatex to format the reference to print the urldate in long form (Australian order) to match my university's style guide. I modified all the other fields using biblatex.cfg

I want the visited date to print the full date

Soto, S. 2013, Ubuntu documentation Install CD Customization, ed. by Community Help Wiki last edited 27 February 2013, visited on 25 September 2015, url: https://help.ubuntu.com/community/InstallCDCustomization.

My biblatex.cfg is

\ProvidesFile{biblatex.cfg}
\renewbibmacro*{date+extrayear}{%
  \iffieldundef{year}
    {}
    {\printtext{%
   \addperiod\space\printfield{labelyear}%
   \printfield{extrayear}}}}
\renewcommand*{\newunitpunct}{\addcomma\space}
\DeclareFieldFormat{urldate}{\bibstring{urlseen}\space{#1}\addcomma}
\renewbibmacro*{url+urldate}{%
\iffieldundef{urlyear}
  {}
  {\setunit*{\addspace}%
   \usebibmacro{urldate}}
\usebibmacro{url}}
\endinput

In my MWE files I have the following fields set

\documentclass{article}
\usepackage[style=authoryear, natbib=true, backend=biber, dateabbrev=false]{biblatex}
\begin{filecontents}{references.bib}
@Online{ubuntu-preseed-dvd,
Title                    = {Ubuntu documentation Install CD Customization},
Author                   = {Soto, S.},
Date                     = {2013-02-27},
Editor                   = {Community Help Wiki last edited 27 February 2013},
Url                      = {https://help.ubuntu.com/community/InstallCDCustomization},
Urldate                  = {2015-09-25}
}
\end{filecontents}
\addbibresource{references.bib}
\begin{document}
\cite{ubuntu-preseed-dvd}.
\printbibliography
\end{document}

Where the date is printed as 09/25/2015.

How can I get biblatex to print as 25 September 2015?

Answer 1

Simply use urldate=long to get the expanded date format for URL dates, the default is the more compressed short you see at the moment.

If you want the months spelled out, you need dateabbrev=false as well (as commented by Florian), that option is independent of the generic abbreviate option that controls whether bibstrings are printed in full/long or short form.

\documentclass[british]{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{babel}
\usepackage{csquotes}

\usepackage[style=authoryear, backend=biber, urldate=long, dateabbrev=false]{biblatex}

\usepackage{filecontents}
\begin{filecontents}{\jobname.bib}
@online{appleby,
  author  = {Humphrey Appleby},
  title   = {On the Importance of the Civil Service},
  date    = {1980},
  url     = {https://example.com/gov/sir-humphrey/importance-civil-service},
  urldate = {2018-08-23},
}
\end{filecontents}

\addbibresource{\jobname.bib}

\begin{document}
\cite{appleby}
\printbibliography
\end{document}

Note that this example uses British and thus easily has the date order dd. mm. yyyy. See http://tex.stackexchange.com/q/129170/35864 if you want to stick to english or american or American spelling.