[Tex/LaTex] Beamer uppercase title

Question

Consider the following MWE:

\documentclass{beamer}

\setbeamerfont{title}{shape=\bfseries, size=\large}
\setbeamerfont{subtitle}{series=\mdseries}
\setbeamerfont{date}{size=\scriptsize}
\setbeamercolor{title}{fg=black}

\title[Bold title]{Uppercase bold title}
\subtitle{Uppercase subtitle}
\author[John Doe]{John Doe}
\institute[]{March 2017}
\date{}

\begin{document}

\maketitle

\end{document}

How can I get make both the \title and \subtitle uppercased but only use bold fonts for the title?
Ideally I would like directly to patchmaketitle or titlepage without defining a new titlepage (with defbeamertemplate*{title page}).

Answer 1

Hoping \setbeamertemplate does not fall in your \defbeamertemplate dislike

\documentclass{beamer}

\setbeamerfont{title}{shape=\bfseries, size=\large}
\setbeamerfont{subtitle}{series=\mdseries}
\setbeamerfont{date}{size=\scriptsize}
\setbeamercolor{title}{fg=black}

\title[Bold title]{Uppercase bold title}
\subtitle{Uppercase subtitle}
\author[John Doe]{John Doe}
\institute[]{March 2017}
\date{}

\makeatletter
\setbeamertemplate{title page}{%
  \vbox{}
  \vfill
  \begingroup
    \centering
    \begin{beamercolorbox}[sep=8pt,center]{title}
      \usebeamerfont{title}\MakeUppercase{\inserttitle}\par%
      \ifx\insertsubtitle\@empty%
      \else%
        \vskip0.25em%
        {\usebeamerfont{subtitle}\usebeamercolor[fg]{subtitle}\MakeUppercase{\insertsubtitle}\par}%
      \fi%     
    \end{beamercolorbox}%
    \vskip1em\par
    \begin{beamercolorbox}[sep=8pt,center]{author}
      \usebeamerfont{author}\insertauthor
    \end{beamercolorbox}
    \begin{beamercolorbox}[sep=8pt,center]{institute}
      \usebeamerfont{institute}\insertinstitute
    \end{beamercolorbox}
    \begin{beamercolorbox}[sep=8pt,center]{date}
      \usebeamerfont{date}\insertdate
    \end{beamercolorbox}\vskip0.5em
    {\usebeamercolor[fg]{titlegraphic}\inserttitlegraphic\par}
  \endgroup
  \vfill
}
\makeatother

\begin{document}

\maketitle

\end{document}