Change language on a per field basis

Question

I am creating a bilingual (main: greek, secondary: english) document with xelatex and polyglossia and I'm using biblatex with biber for the bibliography management. As biblatex is currently setup the bibliography is output in greek which is fine. However, since most of the bibliography is english, the bibliography fields are not hyphenated properly.

If I add autolang=hyphen to the biblatex options, the hyphenation is correct, but the whole entry converts to english which is something I do not want. Is there any way to change language on a per field basis only? For now I have created a simple macro \newcommand{\en}{\selectlanguage{english}} and add \en to the fields I want in english, but this is tiresome and error-prone on a document with way too many references. Is there any way to change the language of the specified fields (title, author, journal, booktitle) but not alter the language of the whole entry?

MWE

\documentclass{book}

% Change these if you want
\newcommand{\MainFont}{Times New Roman}
\newcommand{\SansFont}{Arial}
\newcommand{\MonoFont}{Courier New}

\usepackage{filecontents}

\begin{filecontents}{bibliography.bib}
  @article{anarticle,
    author={Lathrop, J.W.},
    journal={Electron Devices, IRE Transactions on},
    title={Photolithographic fabrication techniques for transistors},
    year={1958},
    month={April},
    volume={5},
    number={2},
    pages={117},
    doi={10.1109/T-ED.1958.14395},
    ISSN={0096-2430},
    langid={english},
    hyphenation={english}
  }
\end{filecontents}

\usepackage{fontspec}
\usepackage{polyglossia}
\setmainlanguage{greek}
\setotherlanguage{english}
\usepackage[backend=biber,style=alphabetic,maxcitenames=2]{biblatex}
\setmainfont[Mapping=tex-text,Ligatures={TeX,Common}]{\MainFont}
\setsansfont[Mapping=tex-text,Ligatures={TeX,Common}]{\SansFont}
\setmonofont[Mapping=tex-text,Ligatures={TeX,Common}]{\MonoFont}
\newfontfamily\greekfont[Script=Greek,Mapping=tex-text,Ligatures={Common,TeX}]{\MainFont}
\newfontfamily\greekfontsf[Script=Greek,Mapping=tex-text,Ligatures={Common,TeX}]{\SansFont}
\newfontfamily\greekfonttt[Script=Greek,Mapping=tex-text,Ligatures={Common,TeX}]{\MonoFont}

\addbibresource{bibliography.bib}

\begin{document}

\cite{anarticle}

\printbibliography

\end{document}

Answer 1

The autolang=hyphen option does what you want. Here's your example but I've made the margins deliberately large to show the hyphenation. Because of the very big margins this still results in some bad boxes, but this is to be expected. For comparison, the example without autolang=hyphen is given also. (I also corrected the month field to a numeric field, which is what biblatex prefers.)

\documentclass[draft]{article}
\usepackage[margin=2.8in]{geometry}
% Change these if you want
\newcommand{\MainFont}{Times New Roman}
\newcommand{\SansFont}{Arial}
\newcommand{\MonoFont}{Courier New}

\usepackage{filecontents}

\begin{filecontents}{\jobname.bib}
  @article{anarticle,
    author={Lathrop, J.W.},
    journal={Electron Devices, IRE Transactions on},
    title={Photolithographic fabrication techniques for transistors},
    year={1958},
    month={4},
    volume={5},
    number={2},
    pages={117},
    doi={10.1109/T-ED.1958.14395},
    ISSN={0096-2430},
    langid={english},
    hyphenation={english}
  }
\end{filecontents}

\usepackage{fontspec}
\usepackage{polyglossia}
\setmainlanguage{greek}
\setotherlanguage{english}
\usepackage[backend=biber,style=alphabetic,maxcitenames=2,language=auto,autolang=hyphen]{biblatex}
\setmainfont[Mapping=tex-text,Ligatures={TeX,Common}]{\MainFont}
\setsansfont[Mapping=tex-text,Ligatures={TeX,Common}]{\SansFont}
\setmonofont[Mapping=tex-text,Ligatures={TeX,Common}]{\MonoFont}
\newfontfamily\greekfont[Script=Greek,Mapping=tex-text,Ligatures={Common,TeX}]{\MainFont}
\newfontfamily\greekfontsf[Script=Greek,Mapping=tex-text,Ligatures={Common,TeX}]{\SansFont}
\newfontfamily\greekfonttt[Script=Greek,Mapping=tex-text,Ligatures={Common,TeX}]{\MonoFont}

\addbibresource{\jobname.bib}

\begin{document}

\cite{anarticle}

\printbibliography

\end{document}

With the option

Without the option