Bandcamp modified dates, a new option and/or a warning?

[UltimateRiff]

I don't know if it's revealed in the API, but Bandcamp shows up to at least three dates for albums in the page source, the release date, the publish date, and the modified date. I forget what the difference between the first two is, but the third is probably the most helpful, as it shows when the most recent change to the album was (for example, a tracklist change or an album art change, both of which should get a new MusicBrainz release).

I believe the modified date also includes other modifications which wouldn't likely get their own release (like editing the credits or description), so I don't know that we should automatically use that date for the release date, but having a warning and the option to use that date would be a good addition

an example release: https://vyletpony.bandcamp.com/track/alicorntwilight
and the (current) dates given (through the Bandcamp importer script

[phw]

Where did you get the "February 20, 2013" date from? I can't find this anywhere in the source.

In the metadata there are two dates (see https://validator.schema.org/#url=https%3A%2F%2Fvyletpony.bandcamp.com%2Ftrack%2Falicorntwilight), the datePublished, which is 2013-02-21 for your example, and the dateModified, which is 2024-12-27 15:07:36.

but the third is probably the most helpful,

The most helpful is the datePublished, as it is what usually corresponds to the release date. It's the date on which the release becomes available, i.e. for pre-releases this is also in the future.

The dateModified is like an editing timestamp for the entire entry. Whenever anything is edited the timestamp changes. This would also include fixing typos, purchase options or whatever.

so I don't know that we should automatically use that date for the release date

Definitely not, as it would be inaccurate in most cases.

but having a warning and the option to use that date would be a good addition

We should be careful how to phrase such warning. I understand the idea: If the release on BC got edited in a way significant enough to warrant a new release, then have the modification date being used as release date. The problem with this is:

1. It is impossible to tell, whether any release significant change has happened to the page.
2. It is impossible to tell the date of such change.

For you above example: Without further information from the time of release we can't know whether any significant change happened. If we assume there was one, it could have been any day between February 21, 2013, and December 27, 2024.

I'd say the likelihood of December 27, 2024 being incorrect as the release date is higher than February 21, 2013 being correct.

[UltimateRiff]

I don't know how the Bandcamp script handles dates, it might be converting it to my timezone tho, as I'm in the US? idk, but I've seen that several times before

you have several fair points here, as in general it's difficult or impossible to tell what changed unless you're familiar with the artist (or are the artist)

[UltimateRiff]

actually, I just found at least one example where there is no modified date update for a track removal, and I don't know how they did it

https://web.archive.org/web/20240526093045/https://flamingosis1.bandcamp.com/album/maniacs
https://musicbrainz.org/release/bab8a5c1-f6ff-4652-b9c5-828d0d0979f0

the former track 12 was removed in late 2023 or early 2024, yet the modified date wasn't updated to reflect this (it still says Feb 2021, when another track seems to have been removed). the release is still available, and still has the same modified date. (yes, I did spend a lot of time in the Wayback Machine to find this, lol)

[phw]

It all depends on what events the updated timestamp gets changed. I really suspect that is somewhat like an update column on the database level. And removing a track, which is likely in a different table, does not affect it.

I think this just underlines that we should not try to interpret too much into it. I really would stay away from making use of it in Harmony.

[UltimateRiff]

well usually a track removal does update the modified date, like this case: https://musicbrainz.org/edit/87612279

don't know how Flamingosis removed a track without affecting the modified date

[phw]

I looked at what the Bandcamp import user script is doing, see https://github.com/murdos/musicbrainz-userscripts/blob/master/bandcamp_importer.user.js#L60-L73

The metadata this script reads directly on the page from window.TralbumData contains a separate publish_date. Note how this is distinct from the mod_date. Below examples are for this release.

The metadata in the JSON+LD schema does not contain this published date. There the field datePublished equals the release_date from the JavaScript metadata. The dateModified is the same as mod_date.

That means there are separate release_date and publish_date that could be used. The JSON+LD metadata does however not contain them. But Harmony also does not use this but uses metadata from the embedded player. Not exactly sure which data this is, but maybe it also includes the separate values.

But also note how the Bandcamp importer user script only uses the publish_date if release_date is before Bandcamp was launched.

[phw]

About using the publish_date in other cases: In case of pre-releases it will be earlier, the release_date will have the actual release date. E.g. on https://willjohnson.bandcamp.com/album/diamond-city:

release_date: 04 Apr 2025 00:00:00 GMT
publish_date: 14 Jan 2025 14:12:56 GMT

[phw]

I have a patch ready that implements the same logic as the importer script to Harmony. I'll submit a PR later today.