1) take db.clean out of metadata_single.py

2) add db.clean to shutdown func
3) add db.clean to 2 cli funcs that can delete an author
4) add db.ondevice() to return the ondevice string

src/calibre/gui2/dialogs/metadata_single.py

@@ -760,7 +760,6 @@ class MetadataSingleDialog(ResizableDialog, Ui_MetadataSingleDialog):
                         _('Could not open %s. Is it being used by another'
                         ' program?')%fname, show=True)
             raise
-        self.db.clean()
         self.save_state()
         QDialog.accept(self)
         if callable(self.accepted_callback):

src/calibre/gui2/ui.py

@@ -522,6 +522,7 @@ class Main(MainWindow, MainWindowMixin, DeviceMixin, # {{{
 
 
     def shutdown(self, write_settings=True):
+        self.db.clean()
         for action in self.iactions.values():
             if not action.shutting_down():
                 return

src/calibre/library/cli.py

@@ -324,6 +324,7 @@ def do_remove(db, ids):
                 db.delete_book(y)
 
         send_message()
+    db.clean()
 
 def remove_option_parser():
     return get_parser(_(
@@ -449,6 +450,7 @@ def command_show_metadata(args, dbpath):
 def do_set_metadata(db, id, stream):
     mi = OPF(stream)
     db.set_metadata(id, mi)
+    db.clean()
     do_show_metadata(db, id, False)
     send_message()
 

src/calibre/library/database2.py

@@ -332,7 +332,7 @@ class LibraryDatabase2(LibraryDatabase, SchemaUpgrade, CustomColumns):
 
         for prop in ('author_sort', 'authors', 'comment', 'comments', 'isbn',
                      'publisher', 'rating', 'series', 'series_index', 'tags',
-                     'title', 'timestamp', 'uuid', 'pubdate'):
+                     'title', 'timestamp', 'uuid', 'pubdate', 'ondevice'):
             setattr(self, prop, functools.partial(get_property,
                     loc=self.FIELD_MAP['comments' if prop == 'comment' else prop]))
         setattr(self, 'title_sort', functools.partial(get_property,