The problem
I'd like to display conference presentations with a different preposition introducing them. E.g., in English, it would be preferable to have "At: Conference Name" than "In: Conference Name". The latter appears because I've been recording conferences as articles, and the name of the conference as a journal—perhaps there is a better way?
MWE
Here's an MWE for the normal behaviour:
\documentclass{article}
\usepackage{filecontents}
\begin{filecontents}{\jobname.bib}
@article{public2000,
author = {Sam Public},
year = {2000},
journal = {Journal of Amazing Ideas},
title = {Some Hargle Bargle},
pubtype = {peerreviewied}
}
@article{public2001,
author = {Sam Public},
year = {2001},
journal = {Conference of Amazing Ideas},
title = {Some Hargle Bargle},
pubtype = {presentation}
}
\end{filecontents}
\usepackage[backend=biber,style=authoryear-comp]{biblatex}
\addbibresource{\jobname.bib}
\begin{document}
\cite{public2000}, \cite{public2001}
\printbibliography
\end{document}
And here's what it results in:

Attempts at a solution
To obtain the desired behaviour, I've added a pubtype field (see MWE), and I've tried hardcoding the output to "At:" based on the value of pubtype:
\renewbibmacro{in:}{%
\ifentrytype{article}{
\iffieldequalstr{pubtype}{presentation}{%
\printtext{At:\intitlepunct}%
}{%
\printtext{\bibstring{in}\intitlepunct}%
}%
}{\printtext{\bibstring{in}\intitlepunct}}
}
However, it doesn't seem to consider pubtype a valid field—or at least, it doesn't seem to be able to test its value. (The output is unchanged, though it does print "At:" if take it out of the if block.)
I've tried defining pubtype as a field a few different ways based on answers that appeared to be related, but nothing seemed to change anything.


public2001really an@articleor rather an@inprocedings? Note that there already is the fieldentrysubtypewhich you could use instead of a self-definedpubtype. – moewe May 25 '18 at 05:24@articles and@inproceedingses :) Are you implying thatentrysubtypeis limited to just@inproceedings, or does it work for anything? – Jonathan W. May 25 '18 at 06:04entrysubtypecan be used for all entry types. I was just thrown off by the@article, with the intended code what is normally thejournal/journaltitlewould end up after the "At:" and I could not imagine that making sense (a conference is not a journal and vice versa), so I suggested@inproceedingswhere it could make sense. – moewe May 25 '18 at 06:15@inproceedingsfor a conference presentation, then the conference would end up as thebooktitle, which probably makes as much sense asjournalorjournaltitle. And proceedings papers and presentations are different beasts anyway—you might want to cite one or the other, even when they have the same title, author, and year. (Of course the proceedings paper would be preferable as a tangible source of information.) – Jonathan W. May 25 '18 at 06:21@articletype. Using@inproceedingsis probably also a bit of a stretch over the intended meaning (published paper version), but it comes closer in meaning and has the additional advantage ofvenueandeventdatefields. In fact@unpublishedmight be an ever better possibility (that is what the talk is, after all), especially since it supportseventtitle,eventdateandvenuesincebiblatex3.11. – moewe May 25 '18 at 06:26@unpublishedindeed looks like a good fit. Thanks! – Jonathan W. May 25 '18 at 06:51