Path Formats
============

The ``paths:`` section of the config file (see :doc:`config`) lets you specify
the directory and file naming scheme for your music library. Templates
substitute symbols like ``$title`` (any field value prefixed by ``$``) with the
appropriate value from the track's metadata. Beets adds the filename extension
automatically.

For example, consider this path format string: ``$albumartist/$album/$track
$title``

Here are some paths this format will generate:

- ``Yeah Yeah Yeahs/It's Blitz!/01 Zero.mp3``
- ``Spank Rock/YoYoYoYoYo/11 Competition.mp3``
- ``The Magnetic Fields/Realism/01 You Must Be Out of Your Mind.mp3``

Because ``$`` is used to delineate a field reference, you can use ``$$`` to emit
a dollars sign. As with `Python template strings`_, ``${title}`` is equivalent
to ``$title``; you can use this if you need to separate a field name from the
text that follows it.

.. _python template strings: https://docs.python.org/3/library/string.html#template-strings-strings

A Note About Artists
--------------------

Note that in path formats, you almost certainly want to use ``$albumartist`` and
not ``$artist``. The latter refers to the "track artist" when it is present,
which means that albums that have tracks from different artists on them (like
`Stop Making Sense`_, for example) will be placed into different folders!
Continuing with the Stop Making Sense example, you'll end up with most of the
tracks in a "Talking Heads" directory and one in a "Tom Tom Club" directory. You
probably don't want that! So use ``$albumartist``.

.. _stop making sense: https://musicbrainz.org/release/798dcaab-0f1a-4f02-a9cb-61d5b0ddfd36

As a convenience, however, beets allows ``$albumartist`` to fall back to the
value for ``$artist`` and vice-versa if one tag is present but the other is not.

.. _template-functions:

Template Functions
------------------

Beets path formats also support *function calls*, which can be used to transform
text and perform logical manipulations. The syntax for function calls is like
this: ``%func{arg,arg}``. For example, the ``upper`` function makes its argument
upper-case, so ``%upper{beets rocks}`` will be replaced with ``BEETS ROCKS``.
You can, of course, nest function calls and place variable references in
function arguments, so ``%upper{$artist}`` becomes the upper-case version of the
track's artists.

These functions are built in to beets:

- ``%lower{text}``: Convert ``text`` to lowercase.
- ``%upper{text}``: Convert ``text`` to UPPERCASE.
- ``%capitalize{text}``: Make the first letter of ``text`` UPPERCASE and the
  rest lowercase.
- ``%title{text}``: Convert ``text`` to Title Case.
- ``%left{text,n}``: Return the first ``n`` characters of ``text``.
- ``%right{text,n}``: Return the last ``n`` characters of ``text``.
- ``%if{condition,text}`` or ``%if{condition,truetext,falsetext}``: If
  ``condition`` is not empty, and not one of the values ``0`` or ``false`` (case
  insensitive), then returns the second argument. Otherwise, returns the third
  argument if specified (or nothing if ``falsetext`` is left off).
- ``%asciify{text}``: Convert non-ASCII characters to their ASCII equivalents.
  For example, "café" becomes "cafe". Uses the mapping provided by the
  `unidecode module`_. See the :ref:`asciify-paths` configuration option.
- ``%aunique{identifiers,disambiguators,brackets}``: Provides a unique string to
  disambiguate similar albums in the database. See :ref:`aunique`, below.
- ``%sunique{identifiers,disambiguators,brackets}``: Similarly, a unique string
  to disambiguate similar singletons in the database. See :ref:`sunique`, below.
- ``%time{date_time,format}``: Return the date and time in any format accepted
  by strftime_. For example, to get the year some music was added to your
  library, use ``%time{$added,%Y}``.
- ``%first{text,count,skip,sep,join}``: Extract a subset of items from a
  delimited string. Splits ``text`` by ``sep``, skips the first ``skip`` items,
  then returns the next ``count`` items joined by ``join``.

  This is especially useful for multi-valued fields like ``artists`` or
  ``genres`` where you may only want the first artist or a limited number of
  genres in a path.

  Defaults:

  ..
      Comically, you need to follow |semicolon_space| with some punctuation to
      make sure it gets rendered correctly as '; ' in the docs.

  - **count**: 1,
  - **skip**: 0,
  - **sep**: |semicolon_space|,
  - **join**: |semicolon_space|.

  Examples:

  ::

      %first{$genres}             →  returns the first genre
      %first{$genres,2}           →  returns the first two genres, joined by "; "
      %first{$genres,2,1}         →  skips the first genre, returns the next two
      %first{$genres,2,0, , -> }  →  splits by space, joins with " -> "

- ``%ifdef{field}``, ``%ifdef{field,truetext}`` or
  ``%ifdef{field,truetext,falsetext}``: Checks if an flexible attribute
  ``field`` is defined. If it exists, then return ``truetext`` or ``field``
  (default). Otherwise, returns ``falsetext``. The ``field`` should be entered
  without ``$``. Note that this doesn't work with built-in :ref:`itemfields`, as
  they are always defined.

.. _strftime: https://docs.python.org/3/library/time.html#time.strftime

.. _unidecode module: https://pypi.org/project/Unidecode

Plugins can extend beets with more template functions (see
:ref:`templ_plugins`).

.. _aunique:

Album Disambiguation
--------------------

Occasionally, bands release two albums with the same name (c.f. Crystal Castles,
Weezer, and any situation where a single has the same name as an album or EP).
Beets ships with special support, in the form of the ``%aunique{}`` template
function, to avoid placing two identically-named albums in the same directory on
disk.

The ``aunique`` function detects situations where two albums have some identical
fields and emits text from additional fields to disambiguate the albums. For
example, if you have both Crystal Castles albums in your library, ``%aunique{}``
will expand to "[2008]" for one album and "[2010]" for the other. The function
detects that you have two albums with the same artist and title but that they
have different release years.

For full flexibility, the ``%aunique`` function takes three arguments. The first
two are whitespace-separated lists of album field names: a set of *identifiers*
and a set of *disambiguators*. The third argument is a pair of characters used
to surround the disambiguator.

Any group of albums with identical values for all the identifiers will be
considered "duplicates". Then, the function tries each disambiguator field,
looking for one that distinguishes each of the duplicate albums from each other.
The first such field is used as the result for ``%aunique``. If no field
suffices, an arbitrary number is used to distinguish the two albums.

The default identifiers are ``albumartist album`` and the default disambiguators
are ``albumtype year label catalognum albumdisambig releasegroupdisambig``. So
you can get reasonable disambiguation behavior if you just use ``%aunique{}``
with no parameters in your path forms (as in the default path formats), but you
can customize the disambiguation if, for example, you include the year by
default in path formats.

The default characters used as brackets are ``[]``. To change this, provide a
third argument to the ``%aunique`` function consisting of two characters: the
left and right brackets. Or, to turn off bracketing entirely, leave argument
blank.

One caveat: When you import an album that is named identically to one already in
your library, the *first* album—the one already in your library— will not
consider itself a duplicate at import time. This means that ``%aunique{}`` will
expand to nothing for this album and no disambiguation string will be used at
its import time. Only the second album will receive a disambiguation string. If
you want to add the disambiguation string to both albums, just run ``beet move``
(possibly restricted by a query) to update the paths for the albums.

.. _sunique:

Singleton Disambiguation
------------------------

It is also possible to have singleton tracks with the same name and the same
artist. Beets provides the ``%sunique{}`` template to avoid giving these tracks
the same file path.

It has the same arguments as the :ref:`%aunique <aunique>` template, but the
default values are different. The default identifiers are ``artist title`` and
the default disambiguators are ``year trackdisambig``.

Syntax Details
--------------

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

- ``${``, which is ambiguous with the variable reference syntax (like
  ``${title}``). To insert a ``{`` alone, it's always sufficient to just type
  ``{``. You do, however need to use ``$`` to escape a closing brace ``$}``.
- commas are used as argument separators in function calls. Inside of a
  function's argument, use ``$,`` to get a literal ``,`` character. Outside of
  any function argument, escaping is not necessary: ``,`` by itself will produce
  ``,`` in the output.

If a value or function is undefined, the syntax is simply left unreplaced. For
example, if you write ``$foo`` in a path template, this will yield ``$foo`` in
the resulting paths because "foo" is not a valid field name. The same is true of
syntax errors like unclosed ``{}`` pairs; if you ever see template syntax
constructs leaking into your paths, check your template for errors.

If an error occurs in the Python code that implements a function, the function
call will be expanded to a string that describes the exception so you can debug
your template. For example, the second parameter to ``%left`` must be an
integer; if you write ``%left{foo,bar}``, this will be expanded to something
like ``<ValueError: invalid literal for int()>``.

.. _itemfields:

Available Values
----------------

Here's a list of the different values available to path formats. The current
list can be found definitively by running the command ``beet fields``. Note that
plugins can add new (or replace existing) template values (see
:ref:`templ_plugins`).

Ordinary metadata:

- title
- artist
- artist_sort: The "sort name" of the track artist (e.g., "Beatles, The" or
  "White, Jack").
- artist_credit: The track-specific `artist credit`_ name, which may be a
  variation of the artist's "canonical" name.
- album
- albumartist: The artist for the entire album, which may be different from the
  artists for the individual tracks.
- albumartist_sort
- albumartist_credit
- genre
- composer
- grouping
- year, month, day: The release date of the specific release.
- original_year, original_month, original_day: The release date of the original
  version of the album.
- track
- tracktotal
- disc
- disctotal
- lyrics
- comments
- bpm
- comp: Compilation flag.
- albumtype: The MusicBrainz album type; the MusicBrainz wiki has a `list of
  type names`_.
- label
- asin
- catalognum
- script
- language
- country
- albumstatus
- media
- albumdisambig
- disctitle
- encoder

.. _artist credit: https://wiki.musicbrainz.org/Artist_Credit

.. _list of type names: https://musicbrainz.org/doc/Release_Group/Type

Audio information:

- length (in seconds)
- bitrate (in kilobits per second, with units: e.g., "192kbps")
- bitrate_mode (e.g., "CBR", "VBR" or "ABR", only available for the MP3 format)
- encoder_info (e.g., "LAME 3.97.0", only available for some formats)
- encoder_settings (e.g., "-V2", only available for the MP3 format)
- format (e.g., "MP3" or "FLAC")
- channels
- bitdepth (only available for some formats)
- samplerate (in kilohertz, with units: e.g., "48kHz")

MusicBrainz and fingerprint information:

- mb_trackid
- mb_releasetrackid
- mb_albumid
- mb_artistid
- mb_albumartistid
- mb_releasegroupid
- acoustid_fingerprint
- acoustid_id

Library metadata:

- mtime: The modification time of the audio file.
- added: The date and time that the music was added to your library.
- path: The item's filename.

.. _templ_plugins:

Template functions and values provided by plugins
-------------------------------------------------

Beets plugins can provide additional fields and functions to templates. See the
:doc:`/plugins/index` page for a full list of plugins. Some plugin-provided
constructs include:

- ``$missing`` by :doc:`/plugins/missing`: The number of missing tracks per
  album.
- ``$album_artist_no_feat`` by :doc:`/plugins/ftintitle`: The album artist
  without any featured artists
- ``%bucket{text}`` by :doc:`/plugins/bucket`: Substitute a string by the range
  it belongs to.
- ``%the{text}`` by :doc:`/plugins/the`: Moves English articles to ends of
  strings.

The :doc:`/plugins/inline` lets you define template fields in your beets
configuration file using Python snippets. And for more advanced processing, you
can go all-in and write a dedicated plugin to register your own fields and
functions (see :ref:`basic-plugin-setup`).
