Merge pull request #3133 from beetbox/no_clobber

First attempt at fixing #3132.

beets/autotag/__init__.py

@@ -142,34 +142,46 @@ def apply_metadata(album_info, mapping):
         # Compilation flag.
         item.comp = album_info.va
 
-        # Miscellaneous metadata.
-        for field in ('albumtype',
-                      'label',
-                      'asin',
-                      'catalognum',
-                      'script',
-                      'language',
-                      'country',
-                      'albumstatus',
-                      'albumdisambig',
-                      'releasegroupdisambig',
-                      'data_source',):
-            value = getattr(album_info, field)
-            if value is not None:
-                item[field] = value
-        if track_info.disctitle is not None:
-            item.disctitle = track_info.disctitle
-
-        if track_info.media is not None:
-            item.media = track_info.media
-
-        if track_info.lyricist is not None:
-            item.lyricist = track_info.lyricist
-        if track_info.composer is not None:
-            item.composer = track_info.composer
-        if track_info.composer_sort is not None:
-            item.composer_sort = track_info.composer_sort
-        if track_info.arranger is not None:
-            item.arranger = track_info.arranger
-
+        # Track alt.
         item.track_alt = track_info.track_alt
+
+        # Miscellaneous/nullable metadata.
+        misc_fields = {
+            'album': (
+                'albumtype',
+                'label',
+                'asin',
+                'catalognum',
+                'script',
+                'language',
+                'country',
+                'albumstatus',
+                'albumdisambig',
+                'releasegroupdisambig',
+                'data_source',
+            ),
+            'track': (
+                'disctitle',
+                'lyricist',
+                'media',
+                'composer',
+                'composer_sort',
+                'arranger',
+            )
+        }
+
+        # Don't overwrite fields with empty values unless the
+        # field is explicitly allowed to be overwritten
+        for field in misc_fields['album']:
+            clobber = field in config['overwrite_null']['album'].as_str_seq()
+            value = getattr(album_info, field)
+            if value is None and not clobber:
+                continue
+            item[field] = value
+
+        for field in misc_fields['track']:
+            clobber = field in config['overwrite_null']['track'].as_str_seq()
+            value = getattr(track_info, field)
+            if value is None and not clobber:
+                continue
+            item[field] = value

beets/config_default.yaml

@@ -53,6 +53,9 @@ aunique:
     disambiguators: albumtype year label catalognum albumdisambig releasegroupdisambig
     bracket: '[]'
 
+overwrite_null:
+  album: []
+  track: []
 
 plugins: []
 pluginpath: []

docs/reference/config.rst

@@ -303,6 +303,7 @@ The defaults look like this::
 
 See :ref:`aunique` for more details.
 
+
 .. _terminal_encoding:
 
 terminal_encoding