Underlined titles in bibliography with biblatex and ulem packages

Question

I want to underline all titles in a bibliography using the biblatex package with Biber backend and the ulem package. biblatex seems to break ulem's line breaking capabilities. Please consider the following MWE:

\documentclass{article}

\begin{filecontents}{MWE.bib}
    @book{key,
        author = {Super, Max},
        title = {An extraordinary long and meaningless example book title, but unfortunately not correctly wrapped}
    }
\end{filecontents}

\usepackage[normalem]{ulem}
\usepackage[backend=biber]{biblatex}
    \addbibresource{MWE.bib}
    \DeclareFieldFormat*{title}{\uline{#1}}

\begin{document}
    \nocite{*}
    \printbibliography
\end{document}

Is there any workaround? Any help is appreciated.

Answer 1

I found two ways. Using \usefield (biblatex.pdf, page 177)

First way: Redefine bibmacro{title}

The bibmacro{title} is defined in the file biblatex.def as follows:

\newbibmacro*{title}{%
  \ifboolexpr{
    test {\iffieldundef{title}}
    and
    test {\iffieldundef{subtitle}}
  }
    {}
    {\printtext[title]{%
       \printfield[titlecase]{title}%
       \setunit{\subtitlepunct}%
       \printfield[titlecase]{subtitle}}%
     \newunit}%
  \printfield{titleaddon}}

I redefine the bibmacro{title}, in the preamble, as:

\renewbibmacro*{title}{%
  \ifboolexpr{
    test {\iffieldundef{title}}
    and
    test {\iffieldundef{subtitle}}
  }
    {}
    {\printtext{%
     \printtext[titlecase]{\usefield{\uline}{title}}%
     \setunit{\subtitlepunct}%
     \printfield[titlecase]{subtitle}}%
     \newunit}%
  \printfield{titleaddon}}

The MWE:

\documentclass{article}

\begin{filecontents}{MWE.bib}
    @book{key,
        author = {Super, Max},
        title = {An extraordinary long and meaningless example book title, and fortunately correctly wrapped},
        subtitle={A short subtitle},
    }
\end{filecontents}

\usepackage[normalem]{ulem}
\usepackage[backend=biber]{biblatex}
\addbibresource{MWE.bib}

\renewbibmacro*{title}{%
  \ifboolexpr{
    test {\iffieldundef{title}}
    and
    test {\iffieldundef{subtitle}}
  }
    {}
    {\printtext{%
     \printtext[titlecase]{\usefield{\uline}{title}}%
     \setunit{\subtitlepunct}%
     \printfield[titlecase]{subtitle}}%
     \newunit}%
  \printfield{titleaddon}}


\begin{document}
    \nocite{*}
    \printbibliography
\end{document}

EDIT

Second way: Using \DeclareFieldFormat

I found other form using \DeclareFieldFormat and it is not necessary redefine the bibmacro{title}.

The format used in the \printfield{title} is titlecase (In the definition of bibmacro{title}). Then must be redefined this format. This is important because I use \currentfield and it is defined only when used \printfield, not with \printtext.

\DeclareFieldFormat*{titlecase}{
    \ifdef{\currentfield}
      {\ifcurrentfield{title}
         {\usefield{\uline}{\currentfield}}%
         {#1}}
      {#1}}

The \ifdef{\currentfield} is to avoid troubles if the format titlecase is used by a \printtext, for example.

The \ifcurrentfield{title} is to apply the format only to the title field.

Finally, if you would like remove the default emphasis in the title, it is necessary redefine the title format, used by printtext.

\DeclareFieldFormat*{title}{#1}

MWE:

\documentclass{article}

\begin{filecontents}{MWE.bib}
    @book{key,
        author = {Super, Max},
        title = {An extraordinary long and meaningless example book title, and fortunately correctly wrapped},
        subtitle={A short subtitle},
        year={2004},
    }
\end{filecontents}

\usepackage[normalem]{ulem}
\usepackage[backend=biber]{biblatex}
\addbibresource{MWE.bib}

\DeclareFieldFormat*{title}{#1}

\DeclareFieldFormat*{titlecase}{%
    \ifdef{\currentfield}
      {\ifcurrentfield{title}
         {\usefield{\uline}{\currentfield}}%
         {#1}}
      {#1}}

\begin{document}
    \nocite{*}
    \printbibliography
\end{document}

Answer 2

Here are some snippets from the ulem documentation that might explain what you are seeing:

Unlike regular underlining, ulem allows line breaks, and manual hyphen- ation, within the underlined text; but it is far from perfect. It is most suit- able for simple text like LATEX: A document preparation system that may need to be underlined in a manuscript submitted for publication. Again, ulem can only give underlined text for \em when the text is delimited by explicit braces.

and:

Every word is typeset in an underlined box, so automatic hyphenation is disabled, but explicit discretionary hyphens (-) will still be obeyed. Several text-formatting commands are specially supported within the un- derlining: -, \ , ~, \, \newline, \linebreak, \nolinebreak, \penalty, \hskip, \hspace, \hfil, \hfill, \hss. Displayed math is not supported. The special commands do have a problem: they end a group so any local assignments are lost.

and:

One important incompatibility with braces and macro replacement: All the text in braces or coming from a macro is typeset in a box (as if in \mbox). Consequently, braces will suppress stretching and line-breaking in the text they enclose. Moreover, the specially-handled commands -, \, \newline and \linebreak are usually ignored if they appear inside extra braces. They operate only when the braces delimit a command parameter without introducing a level of grouping. (Even though braces delimiting command parameters do not normally imply grouping, many commands will add their own grouping.) Thus, you should try to limit inner braces to short bits of text or for delimiting parameters to commands. For emergency repairs, see the sadistic ‘Marat/Sade’ example below. Syntactical spaces inside braces never cause a problem, nor do spaces in math mode.

This documentation can be found as a link to a PDF from here:

http://www.ctan.org/pkg/ulem

I came across a similar problem with underlining in a different situation. The solution I ultimately came up with, which was barely acceptable for me and may not be acceptable to you, was a kludge a found that cycles through the text to be underlined and treats each word separately. This means that each word is underlined but not the spaces between the words. In a bibliography format this may not be appropriate.

The kludge looks like this:

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%This odd bit plucks words individually
%from a group and undelines each word
%this allows for word-wrapping which otherwise
%does not work well.  The trade off is that
%spaces between words are not underlined
%
\makeatletter
\def\mboxed#1{%
    \@mboxed#1 \@empty
}
\def\@mboxed#1 #2{%
  \uline{#1}\space  % underline from package ulem
   \ifx #2\@empty\else
    \expandafter\@mboxed
   \fi
   #2%
}
\makeatother
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

(I wish I could take credit for that bit of code or even give proper credit to the actual author, but I can't find the link that lead me to it.)

Which I implement in my situation like this: \newcommand{\role}1{\mboxed{#1}}

I have very little knowledge, unfortunately, of Biblatex, so I'm don't know how or even if this solution could be of any value to you.