# In biblatex, make title sentence case but not journal name

To force reference titles to a sentence case I use the following line in my .bbx style file:

\DeclareFieldFormat[article,inbook,incollection,inproceedings,patent,thesis,unpublished]{titlecase}{\MakeSentenceCase*{#1}}

But this also causes the journal name to be written in sentence case, which is unwanted.
Why is that and how can I circumvent that?

A minimal example:

\documentclass{article}

\usepackage{filecontents}

\begin{filecontents}{\jobname.bib}
@article{ref1,
author = {Doe, J. and Dane, D., and Dewy, R.},
year = {2000},
title = {This and That},
journal = {Journal of Deep Understanding of Things},
}

@article{ref2,
author = {Doe, J. and Dewy, D., and Dane, R.},
year = {2000},
title = {The Other},
journal = {Journal of deep understanding of things},
}
\end{filecontents}

\usepackage[style=authoryear-comp,natbib=true,
maxcitenames = 2,
mincitenames = 1,
firstinits = true,
labelyear=true,
uniquename=false,
uniquelist=false,
terseinits = false,
backend=biber]{biblatex}
\DeclareFieldFormat[article,inbook,incollection,inproceedings,patent,thesis,unpublished]{titlecase}{\MakeSentenceCase*{#1}}

\begin{document}

Some text and a ref \citep{ref1}.
Then another ref with same first author and year \citep{ref2}

\printbibliography

\end{document}


gives:

-
Closely related: tex.stackexchange.com/q/22980 –  Audrey Dec 8 '12 at 3:05

The original definition of the bibmacro used to print the journal information is

\newbibmacro*{journal}{%
\iffieldundef{journaltitle}
{}
{\printtext[journaltitle]{%
\printfield[titlecase]{journaltitle}%
\setunit{\subtitlepunct}%
\printfield[titlecase]{journalsubtitle}}}}


Thus the instruction \DeclareFieldFormat[article]{titlecase}{\MakeSentenceCase*{#1}} impact the journal title as well. The solution is to modify the definition of the journal bib macro

\newbibmacro*{journal}{%
\iffieldundef{journaltitle}
{}
{\printtext[journaltitle]{%
\printfield[myplain]{journaltitle}%
\setunit{\subtitlepunct}%
\printfield[myplain]{journalsubtitle}}}}


where we can define a myplain field format that just produce an unformatted value.

\DeclareFieldFormat{myplain}{#1}


-
A directive identical to myplain comes predefined in biblatex.def - it's called noformat. –  Audrey Dec 8 '12 at 16:34