Add album template value in ftintitle plugin (#6164)

## Description

I was hoping to use the functionality from `ftintitle` to set the path's
album artist as the main artist, but that wasn't possible, so I added a
template value `album_artist_no_feat`.

beets/plugins.py

@@ -151,9 +151,9 @@ class BeetsPlugin(metaclass=abc.ABCMeta):
         list
     )
     listeners: ClassVar[dict[EventType, list[Listener]]] = defaultdict(list)
-    template_funcs: TFuncMap[str] | None = None
-    template_fields: TFuncMap[Item] | None = None
-    album_template_fields: TFuncMap[Album] | None = None
+    template_funcs: ClassVar[TFuncMap[str]] | TFuncMap[str] = {}  # type: ignore[valid-type]
+    template_fields: ClassVar[TFuncMap[Item]] | TFuncMap[Item] = {}  # type: ignore[valid-type]
+    album_template_fields: ClassVar[TFuncMap[Album]] | TFuncMap[Album] = {}  # type: ignore[valid-type]
 
     name: str
     config: ConfigView
@@ -219,8 +219,8 @@ class BeetsPlugin(metaclass=abc.ABCMeta):
         self.name = name or self.__module__.split(".")[-1]
         self.config = beets.config[self.name]
 
-        # Set class attributes if they are not already set
-        # for the type of plugin.
+        # If the class attributes are not set, initialize as instance attributes.
+        # TODO: Revise with v3.0.0, see also type: ignore[valid-type] above
         if not self.template_funcs:
             self.template_funcs = {}
         if not self.template_fields:
@@ -368,8 +368,6 @@ class BeetsPlugin(metaclass=abc.ABCMeta):
         """
 
         def helper(func: TFunc[str]) -> TFunc[str]:
-            if cls.template_funcs is None:
-                cls.template_funcs = {}
             cls.template_funcs[name] = func
             return func
 
@@ -384,8 +382,6 @@ class BeetsPlugin(metaclass=abc.ABCMeta):
         """
 
         def helper(func: TFunc[Item]) -> TFunc[Item]:
-            if cls.template_fields is None:
-                cls.template_fields = {}
             cls.template_fields[name] = func
             return func
 
@@ -565,8 +561,7 @@ def template_funcs() -> TFuncMap[str]:
     """
     funcs: TFuncMap[str] = {}
     for plugin in find_plugins():
-        if plugin.template_funcs:
-            funcs.update(plugin.template_funcs)
+        funcs.update(plugin.template_funcs)
     return funcs
 
 
@@ -592,21 +587,20 @@ F = TypeVar("F")
 
 
 def _check_conflicts_and_merge(
-    plugin: BeetsPlugin, plugin_funcs: dict[str, F] | None, funcs: dict[str, F]
+    plugin: BeetsPlugin, plugin_funcs: dict[str, F], funcs: dict[str, F]
 ) -> None:
     """Check the provided template functions for conflicts and merge into funcs.
 
     Raises a `PluginConflictError` if a plugin defines template functions
     for fields that another plugin has already defined template functions for.
     """
-    if plugin_funcs:
-        if not plugin_funcs.keys().isdisjoint(funcs.keys()):
-            conflicted_fields = ", ".join(plugin_funcs.keys() & funcs.keys())
-            raise PluginConflictError(
-                f"Plugin {plugin.name} defines template functions for "
-                f"{conflicted_fields} that conflict with another plugin."
-            )
-        funcs.update(plugin_funcs)
+    if not plugin_funcs.keys().isdisjoint(funcs.keys()):
+        conflicted_fields = ", ".join(plugin_funcs.keys() & funcs.keys())
+        raise PluginConflictError(
+            f"Plugin {plugin.name} defines template functions for "
+            f"{conflicted_fields} that conflict with another plugin."
+        )
+    funcs.update(plugin_funcs)
 
 
 def item_field_getters() -> TFuncMap[Item]:

beetsplug/ftintitle.py

@@ -19,11 +19,11 @@ from __future__ import annotations
 import re
 from typing import TYPE_CHECKING
 
-from beets import plugins, ui
+from beets import config, plugins, ui
 
 if TYPE_CHECKING:
     from beets.importer import ImportSession, ImportTask
-    from beets.library import Item
+    from beets.library import Album, Item
 
 
 def split_on_feat(
@@ -98,6 +98,11 @@ def find_feat_part(
     return feat_part
 
 
+def _album_artist_no_feat(album: Album) -> str:
+    custom_words = config["ftintitle"]["custom_words"].as_str_seq()
+    return split_on_feat(album["albumartist"], False, list(custom_words))[0]
+
+
 class FtInTitlePlugin(plugins.BeetsPlugin):
     def __init__(self) -> None:
         super().__init__()
@@ -129,6 +134,10 @@ class FtInTitlePlugin(plugins.BeetsPlugin):
         if self.config["auto"]:
             self.import_stages = [self.imported]
 
+        self.album_template_fields["album_artist_no_feat"] = (
+            _album_artist_no_feat
+        )
+
     def commands(self) -> list[ui.Subcommand]:
         def func(lib, opts, args):
             self.config.set_args(opts)

docs/changelog.rst

@@ -13,6 +13,7 @@ been dropped.
 New features:
 
 - :doc:`plugins/ftintitle`: Added argument for custom feat. words in ftintitle.
+- :doc:`plugins/ftintitle`: Added album template value ``album_artist_no_feat``.
 - :doc:`plugins/musicbrainz`: Allow selecting tags or genres to populate the
   genres tag.
 - :doc:`plugins/ftintitle`: Added argument to skip the processing of artist and

docs/plugins/ftintitle.rst

@@ -33,6 +33,14 @@ file. The available options are:
 - **custom_words**: List of additional words that will be treated as a marker
   for artist features. Default: ``[]``.
 
+Path Template Values
+--------------------
+
+This plugin provides the ``album_artist_no_feat`` :ref:`template value
+<templ_plugins>` that you can use in your :ref:`path-format-config` in
+``paths.default``. Any ``custom_words`` in the configuration are taken into
+account.
+
 Running Manually
 ----------------
 

docs/reference/pathformat.rst

@@ -281,6 +281,8 @@ 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

test/plugins/test_ftintitle.py

@@ -18,7 +18,7 @@ from collections.abc import Generator
 
 import pytest
 
-from beets.library.models import Item
+from beets.library.models import Album, Item
 from beets.test.helper import PluginTestCase
 from beetsplug import ftintitle
 
@@ -364,3 +364,12 @@ def test_custom_words(
     if custom_words is None:
         custom_words = []
     assert ftintitle.contains_feat(given, custom_words) is expected
+
+
+def test_album_template_value():
+    album = Album()
+    album["albumartist"] = "Foo ft. Bar"
+    assert ftintitle._album_artist_no_feat(album) == "Foo"
+
+    album["albumartist"] = "Foobar"
+    assert ftintitle._album_artist_no_feat(album) == "Foobar"