From 79787cfd9785594a146cd0f29e54dfd86973cc3a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C5=A0ar=C5=ABnas=20Nejus?= <snejus@protonmail.com>
Date: Sat, 14 Sep 2024 04:11:52 +0100
Subject: [PATCH] tagging: fix list albumartists field

---
 beets/autotag/__init__.py | 23 +++++++++++------------
 beets/importer/tasks.py   | 19 +++++++++++--------
 test/plugins/test_edit.py |  9 ++-------
 3 files changed, 24 insertions(+), 27 deletions(-)

diff --git a/beets/autotag/__init__.py b/beets/autotag/__init__.py
index 216f7efee..5484edebe 100644
--- a/beets/autotag/__init__.py
+++ b/beets/autotag/__init__.py
@@ -307,21 +307,20 @@ def apply_metadata(
 
         # MusicBrainz IDs.
         item.mb_trackid = track_info.track_id
-        item.mb_releasetrackid = track_info.release_track_id
-        item.mb_albumid = album_info.album_id
-        if track_info.artist_id:
-            item.mb_artistid = track_info.artist_id
-        else:
-            item.mb_artistid = album_info.artist_id
+        item.mb_releasetrackid = track_info.release_track_id or item.mb_trackid
 
-        if track_info.artists_ids:
-            item.mb_artistids = track_info.artists_ids
-        else:
-            item.mb_artistids = album_info.artists_ids
+        item.mb_albumid = album_info.album_id
+        item.mb_releasegroupid = album_info.releasegroup_id
 
         item.mb_albumartistid = album_info.artist_id
-        item.mb_albumartistids = album_info.artists_ids
-        item.mb_releasegroupid = album_info.releasegroup_id
+        item.mb_albumartistids = album_info.artists_ids or (
+            [ai] if (ai := item.mb_albumartistid) else []
+        )
+
+        item.mb_artistid = track_info.artist_id or item.mb_albumartistid
+        item.mb_artistids = track_info.artists_ids or (
+            [iai] if (iai := item.mb_artistid) else []
+        )
 
         # Compilation flag.
         item.comp = album_info.va
diff --git a/beets/importer/tasks.py b/beets/importer/tasks.py
index e56157ed0..f0ae710ef 100644
--- a/beets/importer/tasks.py
+++ b/beets/importer/tasks.py
@@ -430,14 +430,17 @@ class ImportTask(BaseImportTask):
         elif self.choice_flag in (Action.APPLY, Action.RETAG):
             # Applying autotagged metadata. Just get AA from the first
             # item.
-            if not self.items[0].albumartist:
-                changes["albumartist"] = self.items[0].artist
-            if not self.items[0].albumartists:
-                changes["albumartists"] = self.items[0].artists
-            if not self.items[0].mb_albumartistid:
-                changes["mb_albumartistid"] = self.items[0].mb_artistid
-            if not self.items[0].mb_albumartistids:
-                changes["mb_albumartistids"] = self.items[0].mb_artistids
+            first = self.items[0]
+            if not first.albumartist:
+                changes["albumartist"] = first.artist
+            if not first.albumartists:
+                changes["albumartists"] = first.artists or [first.artist]
+            if not first.mb_albumartistid:
+                changes["mb_albumartistid"] = first.mb_artistid
+            if not first.mb_albumartistids:
+                changes["mb_albumartistids"] = first.mb_artistids or [
+                    first.mb_artistid
+                ]
 
         # Apply new metadata.
         for item in self.items:
diff --git a/test/plugins/test_edit.py b/test/plugins/test_edit.py
index 06c7cad74..6bdcafea2 100644
--- a/test/plugins/test_edit.py
+++ b/test/plugins/test_edit.py
@@ -353,13 +353,8 @@ class EditDuringImporterNonSingletonTest(EditDuringImporterTestCase):
         self.assertItemFieldsModified(
             self.lib.items(),
             self.items_orig,
-            ["title"],
-            [
-                *self.IGNORED,
-                "albumartist",
-                "mb_albumartistid",
-                "mb_albumartistids",
-            ],
+            ["title", "albumartist", "albumartists"],
+            [*self.IGNORED, "mb_albumartistid", "mb_albumartistids"],
         )
         assert all("Edited Track" in i.title for i in self.lib.items())