Bibliography: group references with same title; do not print title field if repeated (or empty)

Question

I have the following MWE with my custom bibliography, but I find myself with many talks with the same title (and author) that I want to group together... I guess I would need to use \iffieldundef and/or \iffieldsequal... this is my best attempt (commenting repeated title and author fields in my bib file):

\documentclass{article}

%%%%%%%%%%%%%%%%
% Bibliography %
%%%%%%%%%%%%%%%%

\RequirePackage[style=verbose, maxnames=99, sorting=ydnt, backend=biber]{biblatex}

\DeclareFieldFormat[article]{title}{#1\par}
\DeclareFieldFormat[misc]{title}{#1\par}
\DeclareFieldFormat[thesis]{title}{#1\par}

\DeclareBibliographyDriver{article}{%
  \printfield{title}%
  \newblock%
  \printnames{author}%
  \par%
  \newblock%
  {%
    \usebibmacro{journal+issuetitle}%
    \setunit{\space}%
    \printfield{pages}%
    \newunit%
    \printlist{publisher}%
    %\setunit*{\addcomma\space}%
    %\printfield{year}%included in issuetitle
    \newunit%
  }
  \par\vspace{0.3\baselineskip}
}

\DeclareBibliographyDriver{misc}{%
  \printfield{title}%
  \newblock%
  \printnames{author}%
  \par%
  \newblock%
  {%
    \printfield{type} (\printfield{month} \printfield{year})
    \setunit{\addperiod\space}%
    \printfield{note}%
    \setunit*{\addcomma\space}%
    \printlist{location}%
    \newunit%
  }
  \par\vspace{0.3\baselineskip}
}

\DeclareBibliographyDriver{thesis}{%
  \printfield{title}%
  \newblock%
  \printnames{author}%
  \par%
  \newblock%
  {%
    \printfield{type}
    \setunit{\addperiod\space}%
    \usebibmacro{institution+location+date}%includes year
    \setunit{\addperiod\space}%
    \printfield{url}%
    \newunit%
  }
  \par\vspace{0.3\baselineskip}
}

\DeclareNameFormat{author}{%
  \ifblank{#3}{}{#3\space}#1%
  \ifthenelse{\value{listcount}<\value{liststop}}
    {\addcomma\space}
    {}%
}

\newcommand{\printbibsection}[1]{
  \begin{refsection}
    \nocite{*}
    \printbibliography[sorting=chronological, type={#1}, heading=none]
  \end{refsection}
}

\DeclareSortingScheme{chronological}{
  \sort[direction=descending]{\field{year}}
  \sort[direction=descending]{\field{month}}
  \sort[direction=descending]{\field{day}} %I include the day in entries in the same month and year
}

\begin{filecontents}{\jobname.bib}
@misc{Doe2013b,
location = {This University},
note = {Poster Symposium},
author = {Doe, John},
title = {{Investigating tissue-specificity}},
type = {POSTER},
month = {Sep},
year = {2013}
}
@misc{Doe2014c,
location = {This Other Center},
author = {Doe, John},
title = {{Variability in gene expression}},
type = {TALK},
month = {Sep},
year = {2014}
}
@misc{Doe2014b,
location = {This School},
%author = {Doe, John},
%title = {{Variability in gene expression}},
type = {TALK},
day = 30, %I include the day in entries in the same month and year
month = {Jul},
year = {2014}
}
@misc{Doe2014a,
location = {This Center},
%author = {Doe, John},
%title = {{Variability in gene expression}},
type = {TALK},
day = 23, %I include the day in entries in the same month and year
month = {Jul},
year = {2014}
}
@misc{Doe2014,
location = {This College},
note = {Annual International Symposium},
%author = {Doe, John},
%title = {{Variability in gene expression}},
type = {POSTER},
month = {May},
year = {2014}
}
\end{filecontents}

\addbibresource{\jobname.bib}
\begin{document}

\printbibsection{misc}
\end{document}

Which produces the following:

I would like to remove the \newblocks between TALKS/POSTERS, including a hyphen before them... Anybody? Thanks!

EDIT

commenting repeated titles and using \iffieldundef I produced the following MWE:

\documentclass{article}

\usepackage{fontawesome}
\newfontfamily{\FA}{FontAwesome}

%%%%%%%%%%%%%%%%
% Bibliography %
%%%%%%%%%%%%%%%%

\RequirePackage[style=verbose, maxnames=99, sorting=ydnt, backend=biber]{biblatex}

\DeclareFieldFormat[misc]{title}{#1\par}

\newbibmacro*{newtitle}{%
  \iffieldundef{title}
  {}
  {\printfield{title}%
  \newblock
  \printnames{author}%
  \par
  \newblock
  }
}

\DeclareBibliographyDriver{misc}{%
  \usebibmacro{newtitle}%
  {%
    \faCaretRight \hspace{1px}%
    \printfield{type} (\printfield{month} \printfield{year})%
    \setunit{\addperiod\space}%
    \printfield{note}%
    \setunit*{\addcomma\space}%
    \printlist{location}%
    \newunit%
  }
  \par\vspace{0.3\baselineskip}
}

\DeclareNameFormat{author}{%
  \ifblank{#3}{}{#3\space}#1%
  \ifthenelse{\value{listcount}<\value{liststop}}
    {\addcomma\space}
    {}%
}

\newcommand{\printbibsection}[1]{
  \begin{refsection}
    \nocite{*}
    \printbibliography[sorting=chronological, type={#1}, heading=none]
  \end{refsection}
}

\DeclareSortingScheme{chronological}{
  \sort[direction=descending]{\field{year}}
  \sort[direction=descending]{\field{month}}
  \sort[direction=descending]{\field{day}} %I include the day in entries in the same month and year
}

\begin{filecontents}{\jobname.bib}
@misc{Doe2013b,
location = {This University},
note = {Poster Symposium},
author = {Doe, John},
title = {{Investigating tissue-specificity}},
type = {POSTER},
month = {Sep},
year = {2013}
}
@misc{Doe2014c,
location = {This Other Center},
author = {Doe, John},
title = {{Variability in gene expression}},
type = {TALK},
month = {Sep},
year = {2014}
}
@misc{Doe2014b,
location = {This School},
author = {Doe, John},
%title = {{Variability in gene expression}},
type = {TALK},
day = 30, %I include the day in entries in the same month and year
month = {Jul},
year = {2014}
}
@misc{Doe2014a,
location = {This Center},
author = {Doe, John},
%title = {{Variability in gene expression}},
type = {TALK},
day = 23, %I include the day in entries in the same month and year
month = {Jul},
year = {2014}
}
@misc{Doe2014,
location = {This College},
note = {Annual International Symposium},
author = {Doe, John},
%title = {{Variability in gene expression}},
type = {POSTER},
month = {May},
year = {2014}
}
\end{filecontents}

\addbibresource{\jobname.bib}
\begin{document}

\printbibsection{misc}
\end{document}

Which produces this:

Which is more or less what I want, but now I face the problem of INDENTATIONS!! How can I get the new TALK/POSTER lines to have the same indentation as the first one?? One weird thing I noticed is that if I remove the % after

 \newbibmacro*{newtitle}{

or

 \DeclareBibliographyDriver{misc}{

the indentation changes... WHY IS THAT?? However, I never get to have the same indentation with the new lines as with the first line... Besides, the space between TALKS/POSTERS should also be the same as the space between the author and the first TALK...

Thanks again!

Answer 1

Maybe it is not the most elegant solution, as it requires to comment title fields of bibliography entries, and adjust manually the indent with hspace... besides, I cannot manage to have a bigger space after the last entry in a group. But here is a MWE:

\documentclass{article}

\usepackage{fontawesome}
\newfontfamily{\FA}{FontAwesome}

%%%%%%%%%%%%%%%%
% Bibliography %
%%%%%%%%%%%%%%%%

\RequirePackage[style=verbose, maxnames=99, sorting=ydnt, backend=biber]{biblatex}

\DeclareFieldFormat[misc]{title}{#1\par}

\newbibmacro*{newtitle}{%
  \iffieldundef{title}
  {\hspace{11.65px}%
  }
  {\printfield{title}%
  \par\vspace{0.1\baselineskip}%
  \newblock
  \printnames{author}%
  \par\vspace{0.1\baselineskip}%
  \newblock
  }
}

\DeclareBibliographyDriver{misc}{%
  \usebibmacro{newtitle}%
  {\scriptsize \faCaretRight}
  {%
    \footnotesize
    \printfield{type} (\printfield{month} \printfield{year})%
    \setunit{\addperiod\space}%
    \printfield{note}%
    \setunit*{\addcomma\space}%
    \printlist{location}%
    \newunit
  }
  \par\vspace{0.1\baselineskip}
}

\DeclareNameFormat{author}{%
  \ifblank{#3}{}{#3\space}#1%
  \ifthenelse{\value{listcount}<\value{liststop}}
    {\addcomma\space}
    {}%
}

\newcommand{\printbibsection}[1]{
  \begin{refsection}
    \nocite{*}
    \printbibliography[sorting=chronological, type={#1}, heading=none]
  \end{refsection}
}

\DeclareSortingScheme{chronological}{
  \sort[direction=descending]{\field{year}}
  \sort[direction=descending]{\field{month}}
  \sort[direction=descending]{\field{day}} %I include the day in entries in the same month and year
}

\begin{filecontents}{\jobname.bib}
@misc{Doe2013b,
location = {This University},
note = {Poster Symposium},
author = {Doe, John},
title = {{Investigating tissue-specificity}},
type = {POSTER},
month = {Sep},
year = {2013}
}
@misc{Doe2014c,
location = {This Other Center},
author = {Doe, John},
title = {{Variability in gene expression}},
type = {TALK},
month = {Sep},
year = {2014}
}
@misc{Doe2014b,
location = {This School},
author = {Doe, John},
%title = {{Variability in gene expression}},
type = {TALK},
day = 30, %I include the day in entries in the same month and year
month = {Jul},
year = {2014}
}
@misc{Doe2014a,
location = {This Center},
author = {Doe, John},
%title = {{Variability in gene expression}},
type = {TALK},
day = 23, %I include the day in entries in the same month and year
month = {Jul},
year = {2014}
}
@misc{Doe2014,
location = {This College},
note = {Annual International Symposium},
author = {Doe, John},
%title = {{Variability in gene expression}},
type = {POSTER},
month = {May},
year = {2014}
}
\end{filecontents}

\addbibresource{\jobname.bib}
\begin{document}

\printbibsection{misc}
\end{document}

Which produces:

Answer 2

You can sorting the bibliography entries using title - author - date fields. In this way, equal titles will be treated one after another and you can save the first title (\savefield) and compare with the others. If equals, no titles will be printed, if different will be printed.

The same logic is applied to author field, but in second priority and using \savename.

Below a MWE using your bibtex entries that have the same author name.

    \documentclass{article}
\RequirePackage[style=verbose, maxnames=99, sorting=ydnt, backend=biber]{biblatex}
%%%%%%%%%%%%%%%%
% Bibliography %
%%%%%%%%%%%%%%%%
\DeclareFieldFormat[misc]{title}{#1\}
\newbibmacro*{bib:svtitle}{%
  \savefield{title}{\lasttitle}}
\newbibmacro*{bib:svauthor}{%
  \savename{author}{\lastauthor}}
\newbibmacro*{verifytitle}{%
    \iffieldequals{title}{\lasttitle}{\hspace{\bibhang}}{%
        \printfield{title}\undef\lastauthor}%
    \usebibmacro{bib:svtitle}%
}
\renewbibmacro*{finentry}{\adddot\finentry}
\newbibmacro*{verifyauthor}{%
    \ifnameequals{author}{\lastauthor}
        {}
        {\printnames{author}\}%
    \usebibmacro{bib:svauthor}}
\newbibmacro*{newtitle}{%
    \usebibmacro{verifytitle}}
\newbibmacro*{newauthor}{%
    \usebibmacro{verifyauthor}}
\DeclareBibliographyDriver{misc}{%
  \usebibmacro{newtitle}%
  \usebibmacro{newauthor}%
  {%
    \printtext{--\space}\printfield{type} (\printfield{month} \printfield{year})%
    \setunit{\addperiod\space}%
    \printfield{note}%
    \setunit*{\addcomma\space}%
    \printlist{location}%
  }
  \usebibmacro{finentry}%
}
\DeclareSortingScheme{chronological}{
  \sort{\field{title}}
  \sort{\name{author}}
  \sort[direction=descending]{\field{year}}
  \sort[direction=descending]{\field{month}}
  \sort[direction=descending]{\field{day}} 
}
\newcommand{\printbibsection}[1]{
  \begin{refsection}
    \nocite{*}
    \printbibliography[sorting=chronological, type={#1}, heading=none]
  \end{refsection}
}
\begin{filecontents}{\jobname.bib}
@misc{Doe2013b,
location = {This University},
note = {Poster Symposium},
author = {Doe, John},
title = {{Investigating tissue-specificity}},
type = {POSTER},
month = {Sep},
year = {2013}
}
@misc{Doe2014c,
location = {This Other Center},
author = {Doe, John},
title = {{Variability in gene expression}},
type = {TALK},
month = {Sep},
year = {2014}
}
@misc{Doe2014b,
location = {This School},
author = {Doe, John},
title = {{Variability in gene expression}},
type = {TALK},
day = 30, %I include the day in entries in the same month and year
month = {Jul},
year = {2014}
}
@misc{Doe2014a,
location = {This Center},
author = {Doe, John},
title = {{Variability in gene expression}},
type = {TALK},
day = 23, %I include the day in entries in the same month and year
month = {Jul},
year = {2014}
}
@misc{Doe2014,
location = {This College},
note = {Annual International Symposium},
author = {Doe, John},
title = {{Variability in gene expression}},
type = {POSTER},
month = {May},
year = {2014}
}
\end{filecontents}
\addbibresource{\jobname.bib}
\begin{document}
    \printbibsection{misc}
\end{document}

Below a MWE with more bibtex entries that have entries with the same title, but different author.

\documentclass{article}
\RequirePackage[style=verbose, maxnames=99, sorting=ydnt, backend=biber]{biblatex}
%%%%%%%%%%%%%%%%
% Bibliography %
%%%%%%%%%%%%%%%%
\DeclareFieldFormat[misc]{title}{#1\}
\DeclareFieldFormat[misc]{type}{#1}
\newbibmacro*{bib:svtitle}{%
  \savefield{title}{\lasttitle}}
\newbibmacro*{bib:svauthor}{%
  \savename{author}{\lastauthor}}
\newbibmacro*{verifytitle}{%
    \iffieldequals{title}{\lasttitle}{\hspace{\bibhang}}{%
        \printfield{title}}%
    \usebibmacro{bib:svtitle}%
}
\renewbibmacro*{finentry}{\adddot\finentry}
\newbibmacro*{verifyauthor}{%
    \ifnameequals{author}{\lastauthor}
        {}
        {\printnames{author}\}%
    \usebibmacro{bib:svauthor}}
\newbibmacro*{newtitle}{%
    \usebibmacro{verifytitle}}
\newbibmacro*{newauthor}{%
    \usebibmacro{verifyauthor}}
\DeclareBibliographyDriver{misc}{%
  \usebibmacro{newtitle}%
  \usebibmacro{newauthor}%
  {%
    \printtext{--\space}\printfield{type} (\printfield{month} \printfield{year})%
    \setunit{\addperiod\space}%
    \printfield{note}%
    \setunit*{\addcomma\space}%
    \printlist{location}%
  }
  \usebibmacro{finentry}%
}
\DeclareSortingScheme{chronological}{
  \sort{\field{title}}
  \sort{\name{author}}
  \sort[direction=descending]{\field{year}}
  \sort[direction=descending]{\field{month}}
  \sort[direction=descending]{\field{day}} 
}
\newcommand{\printbibsection}[1]{
  \begin{refsection}
    \nocite{*}
    \printbibliography[sorting=chronological, type={#1}, heading=none]
  \end{refsection}
}
\begin{filecontents}{\jobname.bib}
@misc{Doe2013,
location = {This University},
note = {Poster Symposium},
author = {Doe, John First},
title = {{Investigating tissue-specificity}},
type = {POSTER},
month = {Sep},
year = {2013}
}
@misc{Doe2014a,
location = {This Other Center},
author = {Doe, John Second},
title = {{Variability in gene expression}},
type = {TALK},
month = {Sep},
year = {2014}
}
@misc{Doe2014b,
location = {This School},
author = {Moe, John},
title = {{Variability in gene expression}},
type = {TALK},
day = 30, %I include the day in entries in the same month and year
month = {Jul},
year = {2014}
}
@misc{Doe2014c,
location = {This School},
author = {Moe, John},
title = {{Variability in gene expression}},
type = {TALK},
day = 30, %I include the day in entries in the same month and year
month = {Jul},
year = {2014}
}
@misc{Moe2014d,
location = {This School},
author = {Moe, John},
title = {{Other title in gene expression}},
type = {TALK},
day = 30, %I include the day in entries in the same month and year
month = {Jul},
year = {2014}
}
@misc{Doe2014e,
location = {This Center},
author = {Doe, John},
title = {{Variability in gene expression}},
type = {TALK},
day = 23, %I include the day in entries in the same month and year
month = {Jul},
year = {2014}
}
@misc{Doe2014f,
location = {This College},
note = {Annual International Symposium},
author = {Doe, John},
title = {{Other title in gene expression}},
type = {POSTER},
month = {May},
year = {2014}
}
\end{filecontents}
\addbibresource{\jobname.bib}
\begin{document}
    \printbibsection{misc}
\end{document}

EDIT

It was changed the 'Variability' author name to 'Moe' and fixed the point '2' in the @DaniCee comment. For this was added undef\lasttitle every time that is printed a new title. To fix the problem with the entries order was changed the sorting to year-month-title-day.

\documentclass{article}
\RequirePackage[style=verbose, maxnames=99, sorting=ydnt, backend=biber]{biblatex}
%%%%%%%%%%%%%%%%
% Bibliography %
%%%%%%%%%%%%%%%%
\DeclareFieldFormat[misc]{title}{#1\}
\DeclareFieldFormat[misc]{type}{#1}
\newbibmacro*{bib:svtitle}{%
  \savefield{title}{\lasttitle}}
\newbibmacro*{bib:svauthor}{%
  \savename{author}{\lastauthor}}
\newbibmacro*{verifytitle}{%
    \iffieldequals{title}{\lasttitle}{\hspace{\bibhang}}{%
        \printfield{title}%
        \undef\lastauthor}%
    \usebibmacro{bib:svtitle}%
}
\renewbibmacro*{finentry}{\adddot\finentry}
\newbibmacro*{verifyauthor}{%
    \ifnameequals{author}{\lastauthor}
        {}
        {\printnames{author}\}%
    \usebibmacro{bib:svauthor}}
\newbibmacro*{newtitle}{%
    \usebibmacro{verifytitle}}
\newbibmacro*{newauthor}{%
    \usebibmacro{verifyauthor}}
\DeclareBibliographyDriver{misc}{%
  \usebibmacro{newtitle}%
  \usebibmacro{newauthor}%
  {%
    \printtext{--\space}\printfield{type} (\printfield{month} \printfield{year})%
    \setunit{\addperiod\space}%
    \printfield{note}%
    \setunit*{\addcomma\space}%
    \printlist{location}%
  }
  \usebibmacro{finentry}%
}
\DeclareSortingScheme{chronological}{
  \sort[direction=descending]{\field{year}}
  \sort[direction=descending]{\field{month}}
  \sort{\field{title}}
  \sort[direction=descending]{\field{day}} 
}
\newcommand{\printbibsection}[1]{
  \begin{refsection}
    \nocite{*}
    \printbibliography[sorting=chronological, type={#1}, heading=none]
  \end{refsection}
}
\begin{filecontents}{\jobname.bib}
@misc{Doe2013,
location = {This University},
note = {Poster Symposium},
author = {Doe, John First},
title = {{Investigating tissue-specificity}},
type = {POSTER},
month = {Sep},
year = {2013}
}
@misc{Doe2014a,
location = {This Other Center},
author = {Moe, John Second},
title = {{Variability in gene expression}},
type = {TALK},
month = {Sep},
year = {2014}
}
@misc{Doe2014b,
location = {This School},
author = {Moe, John},
title = {{Variability in gene expression}},
type = {TALK},
day = 30, %I include the day in entries in the same month and year
month = {apr},
year = {2014}
}
@misc{Doe2014c,
location = {This School},
author = {Moe, John},
title = {{Variability in gene expression}},
type = {TALK},
day = 30, %I include the day in entries in the same month and year
month = {June},
year = {2014}
}
@misc{Moe2014d,
location = {This School},
author = {Moe, John},
title = {{Other title in gene expression}},
type = {TALK},
day = 30, %I include the day in entries in the same month and year
month = {oct},
year = {2012}
}
@misc{Doe2014e,
location = {This Center},
author = {Moe, John},
title = {{Variability in gene expression}},
type = {TALK},
day = 23, %I include the day in entries in the same month and year
month = {Jul},
year = {2014}
}
@misc{Doe2014f,
location = {This College},
note = {Annual International Symposium},
author = {Doe, John},
title = {{Other title in gene expression}},
type = {POSTER},
month = {May},
year = {2014}
}
\end{filecontents}
\addbibresource{\jobname.bib}
\begin{document}
    \printbibsection{misc}
\end{document}