Fall back to track artist tags for genre on comps.

Commit 334eba9d28 added support for
falling back to the album artist's folksonomy tags for releases/release
groups without tags. This change adds further support to that to allow
compilation releases to use the track artists' tags since album artist
won't work.

picard/mbxml.py

@@ -281,6 +281,17 @@ def recording_to_metadata(node, track):
             m['~recordingcomment'] = nodes[0].text
         elif name == 'artist_credit':
             artist_credit_to_metadata(nodes[0], m)
+            if 'name_credit' in nodes[0].children:
+                for name_credit in nodes[0].name_credit:
+                    if 'artist' in name_credit.children:
+                        for artist in name_credit.artist:
+                            trackartist = track.append_track_artist(artist.id)
+                            if 'tag_list' in artist.children:
+                                add_folksonomy_tags(artist.tag_list[0],
+                                                    trackartist)
+                            if 'user_tag_list' in artist.children:
+                                add_user_folksonomy_tags(artist.user_tag_list[0],
+                                                         trackartist)
         elif name == 'relation_list':
             _relations_to_metadata(nodes, m)
         elif name == 'tag_list':

picard/track.py

@@ -37,6 +37,11 @@ _TRANSLATE_TAGS = {
 }
 
 
+class TrackArtist(DataObject):
+    def __init__(self, id):
+        DataObject.__init__(self, id)
+
+
 class Track(DataObject, Item):
 
     def __init__(self, id, album=None):
@@ -45,6 +50,7 @@ class Track(DataObject, Item):
         self.linked_files = []
         self.num_linked_files = 0
         self.metadata = Metadata()
+        self._track_artists = []
 
     def __repr__(self):
         return '<Track %s %r>' % (self.id, self.metadata["title"])
@@ -118,10 +124,10 @@ class Track(DataObject, Item):
 
     def is_pregap(self):
         return self.metadata['~pregap'] == '1'
-    
+
     def is_data(self):
         return self.metadata['~datatrack'] == '1'
-    
+
     def is_silence(self):
         return self.metadata['~silence'] == '1'
 
@@ -136,6 +142,13 @@ class Track(DataObject, Item):
             return True
         return False
 
+    def append_track_artist(self, id):
+        """Append artist id to the list of track artists
+        and return an TrackArtist instance"""
+        track_artist = TrackArtist(id)
+        self._track_artists.append(track_artist)
+        return track_artist
+
     def _customize_metadata(self):
         tm = self.metadata
 
@@ -163,8 +176,13 @@ class Track(DataObject, Item):
         if self.album.release_group:
             self.merge_folksonomy_tags(tags, self.album.release_group.folksonomy_tags)
         if not tags and config.setting['artists_tags']:
-            for artist in self.album.get_album_artists():
-                self.merge_folksonomy_tags(tags, artist.folksonomy_tags)
+            # For compilations use each track's artists to look up tags
+            if self.metadata['musicbrainz_albumartistid'] == VARIOUS_ARTISTS_ID:
+                for artist in self._track_artists:
+                    self.merge_folksonomy_tags(tags, artist.folksonomy_tags)
+            else:
+                for artist in self.album.get_album_artists():
+                    self.merge_folksonomy_tags(tags, artist.folksonomy_tags)
         # Ignore tags with zero or lower score
         tags = dict((name, count) for name, count in tags.items() if count > 0)
         if not tags: