Do not delete the genres tag when musicbrainz.genres is False.

beetsplug/mbsync.py

@@ -16,7 +16,7 @@
 
 from collections import defaultdict
 
-from beets import library, metadata_plugins, ui, util
+from beets import config, library, metadata_plugins, ui, util
 from beets.autotag.distance import Distance
 from beets.autotag.hooks import AlbumMatch, TrackMatch
 from beets.plugins import BeetsPlugin, apply_item_changes
@@ -25,6 +25,11 @@
 class MBSyncPlugin(BeetsPlugin):
     def __init__(self):
         super().__init__()
+        self.config.add(
+            {
+                "excluded_fields": [],
+            },
+        )
 
     def commands(self):
         cmd = ui.Subcommand("mbsync", help="update metadata from musicbrainz")
@@ -69,6 +74,24 @@ def func(self, lib, opts, args):
         self.singletons(lib, args, move, pretend, write)
         self.albums(lib, args, move, pretend, write)
 
+    def _get_excluded_fields(self):
+        """Return a list of fields to be exluded from updates.
+
+        When ``musicbrainz.genres`` is False, also include the
+        ``genres`` field.
+        """
+        fields = set(self.config["excluded_fields"].as_str_seq())
+        if not config["musicbrainz"]["genres"]:
+            fields.update(["genres"])
+        return fields
+
+    def noneify_fields(self, obj):
+        """
+        Reset the given ``fields`` on an object ``obj`` to  None.
+        """
+        for field in self._get_excluded_fields():
+            setattr(obj, field, None)
+
     def singletons(self, lib, query, move, pretend, write):
         """Retrieve and apply info from the autotagger for items matched by
         query.
@@ -90,6 +113,9 @@ def singletons(self, lib, query, move, pretend, write):
                 )
                 continue
 
+            # Ignore excluded fields by setting them back to None
+            self.noneify_fields(track_info)
+
             # Apply.
             with lib.transaction():
                 TrackMatch(Distance(), track_info, item).apply_metadata()
@@ -118,12 +144,17 @@ def albums(self, lib, query, move, pretend, write):
                 )
                 continue
 
+            # Ignore excluded fields by setting them back to None
+            self.noneify_fields(album_info)
+
             # Map release track and recording MBIDs to their information.
             # Recordings can appear multiple times on a release, so each MBID
             # maps to a list of TrackInfo objects.
             releasetrack_index = {}
             track_index = defaultdict(list)
             for track_info in album_info.tracks:
+                # Ignore excluded fields by setting them back to None
+                self.noneify_fields(track_info)
                 releasetrack_index[track_info.release_track_id] = track_info
                 track_index[track_info.track_id].append(track_info)
 
@@ -164,8 +195,13 @@ def albums(self, lib, query, move, pretend, write):
                 changed = False
                 # Find any changed item to apply changes to album.
                 any_changed_item = items[0]
+
+                # Ignore any excluded fields when displaying changes
+                fields = set(library.Album.item_keys) - set(
+                    self._get_excluded_fields()
+                )
                 for item in items:
-                    item_changed = ui.show_model_changes(item)
+                    item_changed = ui.show_model_changes(item, fields=fields)
                     changed |= item_changed
                     if item_changed:
                         any_changed_item = item

docs/changelog.rst

@@ -38,6 +38,9 @@ New features
 - :doc:`plugins/replaygain`: Conflicting replay gain tags are now removed on
   write. RG_* tags are removed when setting R128_* and vice versa.
 - :doc:`plugins/fetchart`: Add support for WebP images.
+- :doc:`plugins/mbsync`: Add support excluding fields from being updated. The
+      genres tag will no longer be updated/wiped when ``musicbrainz.genres`` is
+      ``false``.
 
 Bug fixes
 ~~~~~~~~~

docs/plugins/mbsync.rst

@@ -10,6 +10,31 @@ contains correct tags, you can speed up the initial import by importing files
 "as-is" and then using ``mbsync`` to write tags according to your beets
 configuration.
 
+Configuration
+-------------
+
+This plugin can be configured like other metadata source plugins as described in
+:ref:`metadata-source-plugin-configuration`.
+
+.. code-block:: yaml
+
+    mbsync:
+        excluded_fields: []
+
+.. conf:: excluded_fields
+    :default: []
+
+    A list of fields to be excluded from updates when mbsync runs.
+
+    Example:
+
+    .. code-block:: yaml
+
+        mbsync:
+            excluded_fields:
+                - genres
+                - composer
+
 Usage
 -----
 

test/plugins/test_mbsync.py

@@ -22,6 +22,10 @@
 class MbsyncCliTest(PluginTestCase):
     plugin = "mbsync"
 
+    def setUp(self):
+        super().setUp()
+        self.config["musicbrainz"]["genres"] = True
+
     @patch(
         "beets.metadata_plugins.album_for_id",
         Mock(
@@ -88,3 +92,124 @@ def test_custom_format(self):
 
         assert "mbsync: Skipping album with no mb_albumid: 'no id'" in logs
         assert "mbsync: Skipping singleton with no mb_trackid: 'no id'" in logs
+
+    @patch(
+        "beets.metadata_plugins.album_for_id",
+        Mock(
+            side_effect=lambda *_: AlbumInfo(
+                album_id="album id",
+                album="new album",
+                tracks=[
+                    TrackInfo(
+                        track_id="track id",
+                        title="new title",
+                        genres=["new genre"],
+                    )
+                ],
+                genres=["new genre"],
+            )
+        ),
+    )
+    @patch(
+        "beets.metadata_plugins.track_for_id",
+        Mock(
+            side_effect=lambda *_: TrackInfo(
+                track_id="singleton id",
+                title="new title",
+                genres=["new genre"],
+            )
+        ),
+    )
+    def test_genres_field_is_ignored_when_musicbrainz_genres_is_false(self):
+        self.config["musicbrainz"]["genres"] = False
+        album_item = Item(
+            album="old album",
+            mb_albumid="album id",
+            mb_trackid="track id",
+            data_source="data_source",
+            genres=["old genre"],
+        )
+        self.lib.add_album([album_item])
+
+        singleton = Item(
+            title="old title",
+            mb_trackid="singleton id",
+            data_source="data_source",
+            genres=["old genre"],
+        )
+        self.lib.add(singleton)
+
+        self.run_command("mbsync")
+
+        singleton.load()
+        assert singleton.title == "new title"
+        assert singleton.genres == ["old genre"]
+
+        album_item.load()
+        assert album_item.title == "new title"
+        assert album_item.mb_trackid == "track id"
+        assert album_item.get_album().album == "new album"
+        assert album_item.get_album().genres == ["old genre"]
+
+    @patch(
+        "beets.metadata_plugins.album_for_id",
+        Mock(
+            side_effect=lambda *_: AlbumInfo(
+                album_id="album id",
+                album="new album",
+                tracks=[
+                    TrackInfo(
+                        track_id="track id",
+                        title="new title",
+                        genres=["new genre"],
+                    )
+                ],
+                genres=["new genre"],
+                script="new script",
+            )
+        ),
+    )
+    @patch(
+        "beets.metadata_plugins.track_for_id",
+        Mock(
+            side_effect=lambda *_: TrackInfo(
+                track_id="singleton id",
+                title="new title",
+                genres=["new genre"],
+                script="new script",
+            )
+        ),
+    )
+    def test_excluded_fields_are_excluded_correctly(self):
+        self.config["mbsync"]["excluded_fields"] = ["script"]
+        album_item = Item(
+            album="old album",
+            mb_albumid="album id",
+            mb_trackid="track id",
+            data_source="data_source",
+            genres=["old genre"],
+            script="old script",
+        )
+        self.lib.add_album([album_item])
+
+        singleton = Item(
+            title="old title",
+            mb_trackid="singleton id",
+            data_source="data_source",
+            script="old script",
+        )
+        self.lib.add(singleton)
+
+        self.run_command("mbsync")
+
+        singleton.load()
+        assert singleton.title == "new title"
+        assert singleton.genres == ["new genre"]
+        assert singleton.script == "old script"
+
+        album_item.load()
+        assert album_item.title == "new title"
+        assert album_item.mb_trackid == "track id"
+        assert album_item.get_album().album == "new album"
+        assert album_item.get_album().genres == ["new genre"]
+        assert album_item.get_album().script == "old script"