First attempt at fixing #3132.

Add a new `no_clobber` config option that contains a list of
"miscellaneous" metadata fields not to be overwritten by empty values.

I'm not entirely happy with the `no_clobber` name. Suggestions welcome.

beets/autotag/__init__.py

@@ -154,9 +154,14 @@ def apply_metadata(album_info, mapping):
                       'albumdisambig',
                       'releasegroupdisambig',
                       'data_source',):
+            # Don't overwrite fields with empty values unless the
+            # field is explicitly allowed to be overwritten
+            clobber = field not in config['no_clobber'].get()
             value = getattr(album_info, field)
-            if value is not None:
-                item[field] = value
+            if value is None and not clobber:
+                continue
+            item[field] = value
+
         if track_info.disctitle is not None:
             item.disctitle = track_info.disctitle
 

beets/config_default.yaml

@@ -30,6 +30,19 @@ import:
     bell: no
     set_fields: {}
 
+no_clobber:
+  - albumtype
+  - label
+  - asin
+  - catalognum
+  - script
+  - language
+  - country
+  - albumstatus
+  - albumdisambig
+  - releasegroupdisambig
+  - data_source
+
 clutter: ["Thumbs.DB", ".DS_Store"]
 ignore: [".*", "*~", "System Volume Information", "lost+found"]
 ignore_hidden: yes

docs/changelog.rst

@@ -63,6 +63,9 @@ New features:
   provider: you can match tracks and albums using the Spotify database.
   Thanks to :user:`rhlahuja`.
   :bug:`3123`
+* A new ``no_clobber`` configuration option allows setting a list of
+  fields not to be overwritten by empty values upon re-importing items.
+  :bug:`3132`
 
 
 Changes:

docs/reference/config.rst

@@ -303,6 +303,31 @@ The defaults look like this::
 
 See :ref:`aunique` for more details.
 
+
+.. _no_clobber:
+
+no_clobber
+~~~~~~~~~~
+
+A list of fields that should not be overwritten by empty values when
+re-importing items.
+
+The default is::
+
+    no_clobber:
+      - albumtype
+      - label
+      - asin
+      - catalognum
+      - script
+      - language
+      - country
+      - albumstatus
+      - albumdisambig
+      - releasegroupdisambig
+      - data_source
+
+
 .. _terminal_encoding:
 
 terminal_encoding