Beets: Template doesn't format at all when contains a comma

[miblodelcarpio]

Problem

Including a comma in a path yields incorrect path.

Running this command in verbose (-vv) mode:

$ beet -vv ls -f 'Music/Pajo, David/%the{$albumartist_sort}/$releasedate. $album%aunique{}/$disc_and_track. $title' Pajo

Led to this problem:

Music/Pajo, David/%the{$albumartist_sort}/$releasedate. $album%aunique{}/$disc_and_track. $title

Simply removing the comma in Pajo, David yields the expected result.

Setup

• OS: Arch Linux
• Python version: 2.7.12-1
• beets version: 1.3.18
• Turning off plugins made problem go away (yes/no): No

My configuration (output of beet config) is:

paths:
    default: Music/%the{$albumartist_sort}/$releasedate. $album%aunique{}/$disc_and_track. $title
    comp: Music/%the{$albumartist_sort}/$releasedate. $album%aunique{}/$disc_and_track. $artist - $title
    albumartist:Aerial M: Music/Pajo, David/%the{$albumartist_sort}/$releasedate. $album%aunique{}/$disc_and_track. $title
    albumartist:Papa M: Music/Pajo, David/%the{$albumartist_sort}/$releasedate. $album%aunique{}/$disc_and_track. $title
    albumartist:Pajo: Music/Pajo, David/%the{$albumartist_sort}/$releasedate. $album%aunique{}/$disc_and_track. $title
    albumtype:soundtrack: Soundtrack/Game/%the{$albumartist_sort}/$releasedate. $album%aunique{}/$disc_and_track. $title
    albumtype:soundtrack comp: Soundtrack/Game/%the{$albumartist_sort}/$releasedate. $album%aunique{}/$disc_and_track. $artist - $title
    albumstatus:bootleg: Music/%the{$albumartist_sort}/Bootlegs/$album%aunique{}/$disc_and_track. $title
item_fields:
    disc_and_track: u'%02i' % (track) if disctotal == 1 else u'%i-%02i' % (disc, track)
    releasedate: u'%02i-%02i-%02i' % (year, month, day) if day else u'%02i-%02i' % (year, month) if month else u'%02i' % (year)
asciify_paths: yes
library: ~/.config/beets/library.db

replace:
    '[\\/]': _
    ^\.: _
    \s+$: ''
    ^\s+: ''

plugins: inline mbsubmit rewrite the
directory: ~/Media/Audio

import:
    move: yes
    write: yes
pathfields: {}
album_fields: {}
the:
    a: yes
    patterns: []
    the: yes
    strip: no
    format: '{0}, {1}'
mbsubmit:
    threshold: medium
    format: $track. $title - $artist ($length)
rewrite: {}

[sampsyo]

Thanks! This looks like a nasty bug in our template parser. Here's an easy way to see what's wrong:

$ beet ls -f '$artist'
$ beet ls -f ',$artist'

Curiously, a comma _following_ the field works fine:

$ beet ls -f '$artist,'

[diego-plan9]

Following a longer than expected _beets-hiatus_, I was looking through the recent issues in order to try to slowly get back into active development - and stumbled upon this issue!

After looking at the syntax details docs (emphasis mine):

The characters $, %, {, }, and , are "special" in the path
template syntax. This means that, for example, if you want a % character to
appear in your paths, you'll need to be careful that you don't accidentally
write a function call. To escape any of these characters (except {), prefix
it with a $.

I believe miblodelcarpio's problem (and the other examples on the followup comment) could be fixed by simply escaping the comma?

$ beet -vv ls -f 'Music/Pajo$, David/%the{$albumartist_sort} ...'
$ beet ls -f '$, $artist'

However, I'm wondering if it would be worth to try to improve the handling of commas in order to reduce confusion: comma (ARG_SEP) seems to be the only Parser.special_char that has a special meaning depending on specific circumstances (ie. only when used inside a group, _if I'm not mistaken_), and arguably the special character that is more likely to be part of a legitimate string (although it might be a stretch - I might not have solid data to backup that assumption :smirk:).

Would it be a good idea to revise the behaviour of the parser, trying to treat ARG_SEP as a special character only when inside a group?

[sampsyo]

Hi, @diego-plan9, and welcome back!

I agree with your analysis here 100%. You can get the comma back by escaping it, but it's likely enough to be used "incorrectly" that I think we can do better. And yes, I think the right solution is pretty much exactly that: the , character shouldn't be "special" when it appears outside of a function's argument (i.e., %f{here} in a function call).

[diego-plan9]

Thanks, sampsyo!

I'll start working with that solution in mind and move the discussion to a pull request whenever a first draft is ready.

[miblodelcarpio]

Oh wow, yes, this does solve my problem! Thank you, @diego-plan9.

Should we close this issue, then, since my problem is essentially fixed (user error!), or leave it open to keep track of the parser development?

[sampsyo]

Let's leave it open. Thanks for checking back in!

[diego-plan9]

Closed after being fixed at #2213