`beet write`: false positive for changes in fields with multiple values

celynw commented 1 month ago

Problem

It seems that for fields which allow multiple tags, the write command might incorrectly say there are changes to be made.

Backstory

I am using the albumtypes plugin to set the 'soundtrack' album type.

My relevant config looks like this:

albumtypes:
  types:
    - soundtrack: "OST"
    - ep: "EP"
    - single: "Single"
    - live: "Live"
    - compilation: "Anthology"
    - remix: "Remix"
  ignore_va: compilation
paths:
  default: $albumartist/$year - $album%aunique{}/%if{$multidisc,$paddisc-}$padtrack $title
  albumtype:soundtrack: Soundtracks/$album/%if{$multidisc,$paddisc-}$padtrack $title
  albumtypes:soundtrack: Soundtracks/$album/%if{$multidisc,$paddisc-}$padtrack $title
musicbrainz:

(I opened a related discussion, which was solved.)

Basically, if 'soundtrack' appears at all in MusicBrainz's albumtypes list, I'll set the main albumtype to soundtrack. This is because I prefer soundtrack to be the highest priority when something belongs to multiple types.

This does work; I checked the database manually, and the types are set correctly:

albumtype	albumtypes
soundtrack	album; soundtrack

I also checked the files themselves and found the data to also be correct.

RELEASETYPE     : album;soundtrack
MUSICBRAINZ_ALBUMTYPE: album;soundtrack

My issue is that when I run beet write, it tells me there are many changes to be made like:

albumtype: album -> soundtrack

This never clears; if I run the command again, it tries to do this again.

The issue seems to related to this part in mediafile:

    albumtypes = ListMediaField(
        MP3ListDescStorageStyle('MusicBrainz Album Type', split_v23=True),
        MP4ListStorageStyle('----:com.apple.iTunes:MusicBrainz Album Type'),
        ListStorageStyle('RELEASETYPE'),
        ListStorageStyle('MUSICBRAINZ_ALBUMTYPE'),
        ASFStorageStyle('MusicBrainz/Album Type'),
    )
    albumtype = albumtypes.single_field()

ListMediaField.single_field returns the first item in albumtypes.

This comes up in the write command, write_items(), where a 'clean_item` is created from the file on disk:

https://github.com/beetbox/beets/blob/b88c09720c3f0782b90f83df74e65680c050392f/beets/ui/commands.py#L2285

It's a bit tricky, because both the file and the database are already correct, but because the write command thought there is a difference, it will attempt to write the corrections anyway.

Beets' database holds both multiple (albumtypes) and single fields (albumtype) for that entry, and the single field can be configured by the user to choose which one from the multiple field
Beets reads a field with multiple values and returns the first one to the write command
Beets writes (only) the multiple values tag to the file
- I haven't investigated with other media file types - this one is an FLAC

If the above is always true, a workaround which works for me is to add

        if item.albumtype in clean_item.albumtypes:
            clean_item.albumtype = item.albumtype

before checking for the changes here:

https://github.com/beetbox/beets/blob/b88c09720c3f0782b90f83df74e65680c050392f/beets/ui/commands.py#L2293

I'm not sure if this is the most robust though.

Also, I guess it could apply to other 'multiple' fields too:

genres
catalognums
languages
mb_artistids
mb_albumartistids

Setup

OS: Ubuntu 22.04
Python version: 3.10.12
beets version: 2.0.0
Turning off plugins made problem go away (yes/no): N/A

celynw commented 1 month ago

And similarly for beet update: adding

            old_item = lib.get_item(item.id)
            if old_item.albumtype in item.albumtypes:
                item.albumtype = old_item.albumtype

before checking for the changes here:

https://github.com/beetbox/beets/blob/b88c09720c3f0782b90f83df74e65680c050392f/beets/ui/commands.py#L1685

snejus commented 3 weeks ago

Thank you, this is an amazing investigation! Linking this to the issue where this problem has been reported first: https://github.com/beetbox/beets/issues/5265

beetbox / beets