Btukfyl

I write in English as well as Chinese. When I cite Chinese work in English paper, I want to include both the English transcription/translation and original Chinese characters. But when I cite Chinese work in Chinese paper, I don't need to include the transcription. Is there a possible and convenient way to switch from these two circumstances, provided I make only one bibtex record for each reference, instead of two (Chinese version .bib and English version)?

I use Biblatex + TeXlive2018 + Win10

Example

When I write in English, I want output be like this:

When I write in Chinese, I want the same two references be like this:

(Biblatex-Chicago style is used)

That is to say:

English reference in English/Chinese writing --> remains English

Chinese reference in English writing --> shows both English and Chinese fields

Chinese reference in Chinese writing --> shows Chinese fields only

This is a proof of concept of a limited alternative which, I'm sure, it won't take long before someone finds an unfixable flaw. But I submit it as an idea. As it stands, it only works for literal fields (I'm using title here as example) and I'm not sure if this could be extended for names and lists. It will very likely generate some problems with biblatex's formatting directives. It is also a fragile setting, as we need to place some macros directly in the bibentry field of interest.

documentclass{article}



usepackage{filecontents}

begin{filecontents}{jobname.bib}

  @book{book1,

    author = {Author},

    title = {caseenglish{Title}casebrazilian{Título}},

    date = {2000},

    location = {Location},

    publisher = {Publisher},

    addendum = {An entry in Brazilian Portuguese, for which we want both titles

      when the language is English and Portuguese title when the langage is

      brazilian},

  }



  @book{book2,

    author = {Author},

    title = {English title},

    date = {2004},

    location = {Location},

    publisher = {Publisher},

    addendum = {An entry in English, which should always be in English},

  }



end{filecontents}



usepackage{iflang}

usepackage[brazilian,english]{babel}

usepackage{csquotes}

usepackage[style=authoryear]{biblatex}



addbibresource{jobname.bib}



newcommand*{caseenglish}[1]{#1}

newcommand*{casebrazilian}[1]{#1}



AtBeginBibliography{%

  IfLanguageName{english}{%

    renewcommand*{casebrazilian}[1]{ #1}%

  }{}%

  IfLanguageName{brazilian}{%

    renewcommand*{caseenglish}[1]{}%

  }{}%

}



begin{document}



nocite{*}



printbibliography



selectlanguage{brazilian}



printbibliography



end{document}