Add support for multiple tags for multiple values

MPD supports multiple tags for some values, such as the artist, the
composer, and the performer. (See
<https://mpd.readthedocs.io/en/latest/protocol.html#tags>.) There
might be multiple artists for a track, in which case mopidy-mpd would
concatenate their names into one value, separated by a semicolon. For
some users and use cases, this can be suboptimal; when tracking the
tracks you listen to on a platform such as Listenbrainz, tracks of
multiple artists do not contribute to the total number of listens of
one of the artists.

This commit changes this behaviour when the `multiple_tags'
configuration variable is set to true, to use multiple tags for values
when applicable instead of concatenating the values.

README.rst

@@ -126,6 +126,12 @@ The following configuration values are available:
   creating a playlist from the given tracks.
   Default: ``m3u``
 
+- ``mpd/multiple_tags``:
+  Use multiple tags when a track has multiple artists, album artists, composers
+  or performers, instead of concatenating the names separated by a semicolon
+  into one tag.
+  Default: false.
+
 
 Limitations
 ===========

mopidy_mpd/__init__.py

@@ -26,6 +26,7 @@ def get_config_schema(self):
         schema["zeroconf"] = config.String(optional=True)
         schema["command_blacklist"] = config.List(optional=True)
         schema["default_playlist_scheme"] = config.String()
+        schema["multiple_tags"] = config.Boolean(optional=True)
         return schema
 
     def setup(self, registry):

mopidy_mpd/dispatcher.py

@@ -239,6 +239,9 @@ class MpdContext:
     #: The subsytems that we want to be notified about in idle mode.
     subscriptions = None
 
+    #: Whether to use multiple tags for e.g. artists.
+    multiple_tags = None
+
     _uri_map = None
 
     def __init__(
@@ -248,6 +251,7 @@ def __init__(
         self.session = session
         if config is not None:
             self.password = config["mpd"]["password"]
+            self.multiple_tags = config["mpd"]["multiple_tags"]
         self.core = core
         self.events = set()
         self.subscriptions = set()

mopidy_mpd/ext.conf

@@ -8,3 +8,4 @@ connection_timeout = 60
 zeroconf = Mopidy MPD server on $hostname
 command_blacklist = listall,listallinfo
 default_playlist_scheme = m3u
+multiple_tags = false

mopidy_mpd/protocol/current_playlist.py

@@ -188,7 +188,9 @@ def playlistfind(context, tag, needle):
         if not tl_tracks:
             return None
         position = context.core.tracklist.index(tl_tracks[0]).get()
-        return translator.track_to_mpd_format(tl_tracks[0], position=position)
+        return translator.track_to_mpd_format(
+            tl_tracks[0], position=position, multiple_tags=context.multiple_tags
+        )
     raise exceptions.MpdNotImplemented  # TODO
 
 
@@ -207,10 +209,13 @@ def playlistid(context, tlid=None):
         if not tl_tracks:
             raise exceptions.MpdNoExistError("No such song")
         position = context.core.tracklist.index(tl_tracks[0]).get()
-        return translator.track_to_mpd_format(tl_tracks[0], position=position)
+        return translator.track_to_mpd_format(
+            tl_tracks[0], position=position, multiple_tags=context.multiple_tags
+        )
     else:
         return translator.tracks_to_mpd_format(
-            context.core.tracklist.get_tl_tracks().get()
+            context.core.tracklist.get_tl_tracks().get(),
+            multiple_tags=context.multiple_tags,
         )
 
 
@@ -241,7 +246,9 @@ def playlistinfo(context, parameter=None):
         raise exceptions.MpdArgError("Bad song index")
     if end and end > len(tl_tracks):
         end = None
-    return translator.tracks_to_mpd_format(tl_tracks, start, end)
+    return translator.tracks_to_mpd_format(
+        tl_tracks, start, end, multiple_tags=context.multiple_tags
+    )
 
 
 @protocol.commands.add("playlistsearch")
@@ -281,7 +288,8 @@ def plchanges(context, version):
     tracklist_version = context.core.tracklist.get_version().get()
     if version < tracklist_version:
         return translator.tracks_to_mpd_format(
-            context.core.tracklist.get_tl_tracks().get()
+            context.core.tracklist.get_tl_tracks().get(),
+            multiple_tags=context.multiple_tags,
         )
     elif version == tracklist_version:
         # A version match could indicate this is just a metadata update, so
@@ -293,7 +301,10 @@ def plchanges(context, version):
         tl_track = context.core.playback.get_current_tl_track().get()
         position = context.core.tracklist.index(tl_track).get()
         return translator.track_to_mpd_format(
-            tl_track, position=position, stream_title=stream_title
+            tl_track,
+            position=position,
+            stream_title=stream_title,
+            multiple_tags=context.multiple_tags,
         )
 
 

mopidy_mpd/protocol/music_db.py

@@ -154,7 +154,9 @@ def find(context, *args):
     if "album" not in query:
         result_tracks += [_album_as_track(a) for a in _get_albums(results)]
     result_tracks += _get_tracks(results)
-    return translator.tracks_to_mpd_format(result_tracks)
+    return translator.tracks_to_mpd_format(
+        result_tracks, multiple_tags=context.multiple_tags
+    )
 
 
 @protocol.commands.add("findadd")
@@ -338,7 +340,11 @@ def listallinfo(context, uri=None):
         else:
             for tracks in lookup_future.get().values():
                 for track in tracks:
-                    result.extend(translator.track_to_mpd_format(track))
+                    result.extend(
+                        translator.track_to_mpd_format(
+                            track, multiple_tags=context.multiple_tags
+                        )
+                    )
     return result
 
 
@@ -390,7 +396,11 @@ def lsinfo(context, uri=None):
         else:
             for tracks in lookup_future.get().values():
                 if tracks:
-                    result.extend(translator.track_to_mpd_format(tracks[0]))
+                    result.extend(
+                        translator.track_to_mpd_format(
+                            tracks[0], multiple_tags=context.multiple_tags
+                        )
+                    )
 
     if uri in (None, "", "/"):
         result.extend(protocol.stored_playlists.listplaylists(context))
@@ -444,7 +454,9 @@ def search(context, *args):
     artists = [_artist_as_track(a) for a in _get_artists(results)]
     albums = [_album_as_track(a) for a in _get_albums(results)]
     tracks = _get_tracks(results)
-    return translator.tracks_to_mpd_format(artists + albums + tracks)
+    return translator.tracks_to_mpd_format(
+        artists + albums + tracks, multiple_tags=context.multiple_tags
+    )
 
 
 @protocol.commands.add("searchadd")

mopidy_mpd/protocol/status.py

@@ -44,7 +44,10 @@ def currentsong(context):
     if tl_track is not None:
         position = context.core.tracklist.index(tl_track).get()
         return translator.track_to_mpd_format(
-            tl_track, position=position, stream_title=stream_title
+            tl_track,
+            position=position,
+            stream_title=stream_title,
+            multiple_tags=context.multiple_tags,
         )
 
 

mopidy_mpd/protocol/stored_playlists.py

@@ -63,7 +63,9 @@ def listplaylistinfo(context, name):
     for uri in track_uris:
         tracks.extend(tracks_map[uri])
     playlist = playlist.replace(tracks=tracks)
-    return translator.playlist_to_mpd_format(playlist)
+    return translator.playlist_to_mpd_format(
+        playlist, multiple_tags=context.multiple_tags
+    )
 
 
 @protocol.commands.add("listplaylists")

mopidy_mpd/translator.py

@@ -18,7 +18,9 @@ def normalize_path(path, relative=False):
     return "/".join(parts)
 
 
-def track_to_mpd_format(track, position=None, stream_title=None):
+def track_to_mpd_format(
+    track, position=None, stream_title=None, multiple_tags=False
+):
     """
     Format track for output to MPD client.
 
@@ -28,6 +30,8 @@ def track_to_mpd_format(track, position=None, stream_title=None):
     :type position: integer
     :param stream_title: the current streams title
     :type position: string
+    :param multiple_tags: whether to use multiple tags for e.g. artists
+    :type multiple_tags: boolean
     :rtype: list of two-tuples
     """
     if isinstance(track, TlTrack):
@@ -42,10 +46,14 @@ def track_to_mpd_format(track, position=None, stream_title=None):
     result = [
         ("file", track.uri),
         ("Time", track.length and (track.length // 1000) or 0),
-        ("Artist", concat_multi_values(track.artists, "name")),
         ("Album", track.album and track.album.name or ""),
     ]
 
+    if multiple_tags:
+        result += multi_tag_list(track.artists, "name", "Artist")
+    else:
+        result.append(("Artist", concat_multi_values(track.artists, "name")))
+
     if stream_title is not None:
         result.append(("Title", stream_title))
         if track.name:
@@ -69,9 +77,16 @@ def track_to_mpd_format(track, position=None, stream_title=None):
         result.append(("MUSICBRAINZ_ALBUMID", track.album.musicbrainz_id))
 
     if track.album is not None and track.album.artists:
-        result.append(
-            ("AlbumArtist", concat_multi_values(track.album.artists, "name"))
-        )
+        if multiple_tags:
+            result += multi_tag_list(track.album.artists, "name", "AlbumArtist")
+        else:
+            result.append(
+                (
+                    "AlbumArtist",
+                    concat_multi_values(track.album.artists, "name"),
+                )
+            )
+
         musicbrainz_ids = concat_multi_values(
             track.album.artists, "musicbrainz_id"
         )
@@ -84,14 +99,20 @@ def track_to_mpd_format(track, position=None, stream_title=None):
             result.append(("MUSICBRAINZ_ARTISTID", musicbrainz_ids))
 
     if track.composers:
-        result.append(
-            ("Composer", concat_multi_values(track.composers, "name"))
-        )
+        if multiple_tags:
+            result += multi_tag_list(track.composers, "name", "Composer")
+        else:
+            result.append(
+                ("Composer", concat_multi_values(track.composers, "name"))
+            )
 
     if track.performers:
-        result.append(
-            ("Performer", concat_multi_values(track.performers, "name"))
-        )
+        if multiple_tags:
+            result += multi_tag_list(track.performers, "name", "Performer")
+        else:
+            result.append(
+                ("Performer", concat_multi_values(track.performers, "name"))
+            )
 
     if track.genre:
         result.append(("Genre", track.genre))
@@ -151,7 +172,29 @@ def concat_multi_values(models, attribute):
     )
 
 
-def tracks_to_mpd_format(tracks, start=0, end=None):
+def multi_tag_list(models, attribute, tag):
+    """
+    Format Mopidy model values for output to MPD client in a list with one tag
+    per value.
+
+    :param models: the models
+    :type models: array of :class:`mopidy.models.Artist`,
+        :class:`mopidy.models.Album` or :class:`mopidy.models.Track`
+    :param attribute: the attribute to use
+    :type attribute: string
+    :param tag: the name of the tag
+    :type tag: string
+    :rtype: list of tuples of string and attribute value
+    """
+
+    return [
+        (tag, getattr(m, attribute))
+        for m in models
+        if getattr(m, attribute, None) is not None
+    ]
+
+
+def tracks_to_mpd_format(tracks, start=0, end=None, multiple_tags=False):
     """
     Format list of tracks for output to MPD client.
 
@@ -164,6 +207,8 @@ def tracks_to_mpd_format(tracks, start=0, end=None):
     :type start: int (positive or negative)
     :param end: position after last track to include in output
     :type end: int (positive or negative) or :class:`None` for end of list
+    :param multiple_tags: whether to use multiple tags for e.g. artists
+    :type multiple_tags: boolean
     :rtype: list of lists of two-tuples
     """
     if end is None:
@@ -173,7 +218,9 @@ def tracks_to_mpd_format(tracks, start=0, end=None):
     assert len(tracks) == len(positions)
     result = []
     for track, position in zip(tracks, positions):
-        formatted_track = track_to_mpd_format(track, position)
+        formatted_track = track_to_mpd_format(
+            track, position, multiple_tags=multiple_tags
+        )
         if formatted_track:
             result.append(formatted_track)
     return result

tests/protocol/__init__.py

@@ -28,7 +28,11 @@ class BaseTestCase(unittest.TestCase):
     def get_config(self):
         return {
             "core": {"max_tracklist_length": 10000},
-            "mpd": {"password": None, "default_playlist_scheme": "dummy"},
+            "mpd": {
+                "password": None,
+                "default_playlist_scheme": "dummy",
+                "multiple_tags": False,
+            },
         }
 
     def setUp(self):  # noqa: N802

tests/test_dispatcher.py

@@ -14,7 +14,13 @@
 
 class MpdDispatcherTest(unittest.TestCase):
     def setUp(self):  # noqa: N802
-        config = {"mpd": {"password": None, "command_blacklist": ["disabled"]}}
+        config = {
+            "mpd": {
+                "password": None,
+                "command_blacklist": ["disabled"],
+                "multiple_tags": False,
+            }
+        }
         self.backend = dummy_backend.create_proxy()
         self.dispatcher = MpdDispatcher(config=config)