Add support for Biber date format

[laurentperrinet]

The previous code was generating invalid dates such as 2018-01-01-01.

[gcushen]

Please describe the problem which you are trying to solve along with an example BibTeX excerpt.

[laurentperrinet]

Description of the problem:

The biblatex has extended support for producing datestamps, as outputed for instance by a bibliography manager like zotero.

This could be a problem in this script as it assumes the standard bibtex format.

Description of the changes:

In the more general case, if a date entry was present in the input bibtex which also contained the month (like "2017-08") or the day (as in ("2019-03-14"), the date field is used in preference.

example BibTeX excerpt

for instance,

@article{BoutinFranciosiniRuffierPerrinet19,
 author = {Boutin, Victor and Franciosini, Angelo and Ruffier, Franck and Perrinet, Laurent U},
 date = {2019-02-20},
 date-modified = {2019-02-25 23:21:37 +0100},
 journal = {submitted to Neural Networks},
 keywords = {sparse coding},
 preprint = {https://arxiv.org/abs/1902.07651},
 title = {Meaningful representations emerge from Sparse Deep Predictive Coding},
 url = {https://arxiv.org/abs/1902.07651},
 year = {2019}
}

transforms into:

+++
title = "Meaningful representations emerge from Sparse Deep Predictive Coding"
date = 2019-02-20
authors = [ "Victor Boutin", "Angelo Franciosini", "Franck Ruffier", "Laurent U Perrinet",]
publication_types = [ "2",]
featured = false
publication = "*submitted to Neural Networks*"
url_pdf = "https://arxiv.org/abs/1902.07651"
tags = [ "sparse coding",]
+++

[gcushen]

So you are suggesting to increase the scope of the tool from just the BibTeX format to consider both the BibTeX and Biber formats?

P.S. I found a nice comparison at https://tex.stackexchange.com/a/25702

[laurentperrinet]

Exactly. The advantage I see in using biblatex are mainly the unicode encoding (for instance for authors) and the format of the date which follows iso 8601.

Maybe the tool could parse a new boolean variable to switch behavior from the old to the new scheme?

[gcushen]

This project uses https://bibtexparser.readthedocs.io/en/master/ to parse references. I can't immediately see that it officially supports the Biber format?

[laurentperrinet]

Indeed, I see no trace of the biblatex format used by biber - it could have been useful to be able to support it fully. The proposed solution in this PR was more to propose to support the timestamp from biblatex without breaking compatibility with the classical bibtex format.

[laurentperrinet]

Do you want me to add a warning about the fact that the library does not aim to fully support ```biblatex`` but that this serves as a working solution?

[cgxeiji]

I would like this feature, as all my references are in biblatex format.

[laurentperrinet]

for the moment, it does not provide with a fully compliance with biblatex, but at least it provides with a fix to not mess with the date ...

[cgxeiji]

for the moment, it does not provide with a fully compliance with biblatex, but at least it provides with a fix to not mess with the date ...

Well, at least it will let me automate the process, because, right now, my references fail to load as I don't have a year entry, but date.