identify albums by existing MB album ID

beets/autotag/__init__.py

@@ -310,6 +310,19 @@ def apply_metadata(items, info):
         item.mb_albumid = mb_albumid
         item.mb_artistid = mb_artistid
 
+def match_by_id(items):
+    # Is there a consensus on the MB album ID?
+    albumids = [item.mb_albumid for item in items if item.mb_albumid]
+    if not albumids:
+        return None
+    
+    # If all album IDs are equal, look up the album.
+    if bool(reduce(lambda x,y: x if x==y else (), albumids)):
+        albumid = albumids[0]
+        return mb.album_for_id(albumid)
+    else:
+        return None
+
 def tag_album(items, search_artist=None, search_album=None):
     """Bundles together the functionality used to infer tags for a
     set of items comprised by an album. Returns everything relevant:
@@ -383,4 +396,3 @@ def tag_album(items, search_artist=None, search_album=None):
             rec = RECOMMEND_NONE
     
     return cur_artist, cur_album, dist_ordered_cands, rec
-

beets/autotag/mb.py

@@ -170,14 +170,14 @@ def match_album(artist, album, tracks=None):
         tracks = release_tracks(release.id)
         yield release_dict(release, tracks)
 
-def match_album_single(artist, album, tracks=None):
-    """Behaves like match_album but, instead of returning an iterator,
-    tries to get just a single result. Returns an info dictionary or
-    None if no suitable match.
+def album_for_id(albumid):
+    """Fetches an album by its MusicBrainz ID and returns an
+    information dictionary. If no match is found, returns None.
     """
-    it = match_album(artist, album, tracks)
+    query = mbws.Query()
+    inc = mbws.ReleaseIncludes(artist=True, tracks=True)
     try:
-        return it.next()
-    except StopIteration:
+        album = _query_wrap(query.getReleaseById, albumid, inc)
+    except mbws.ResourceNotFoundError:
         return None
-
+    return release_dict(album, album.tracks)

test/test_mb.py

@@ -127,19 +127,29 @@ class MBReleaseDictTest(unittest.TestCase):
 
 class MBWhiteBoxTest(unittest.TestCase):
     def test_match_album_finds_el_producto(self):
-        a = mb.match_album_single('the avalanches', 'el producto')
+        a = iter(mb.match_album('the avalanches', 'el producto')).next()
         self.assertEqual(a['album'], 'El Producto')
         self.assertEqual(a['artist'], 'The Avalanches')
         self.assertEqual(len(a['tracks']), 7)
 
     def test_match_album_tolerates_small_errors(self):
-        a = mb.match_album_single('mia', 'kala ')
+        a = iter(mb.match_album('mia', 'kala ')).next()
         self.assertEqual(a['artist'], 'M.I.A.')
         self.assertEqual(a['album'], 'Kala')
 
+class ByIDTest(unittest.TestCase):
+    def test_match_found(self):
+        a = mb.album_for_id('73677f81-86e6-4087-9255-9ee81b8e3dd3')
+        self.assertEqual(a['artist'], 'Paul Simon')
+        self.assertEqual(a['album'], 'Graceland')
+        self.assertTrue(len(a['tracks']) > 0)
+    
+    def test_no_match_returns_none(self):
+        a = mb.album_for_id('bogus-id')
+        self.assertEqual(a, None)
+
 def suite():
     return unittest.TestLoader().loadTestsFromName(__name__)
 
 if __name__ == '__main__':
     unittest.main(defaultTest='suite')
-