db: Clear MappedPlaylists before deleting

Otherwise we end up with a bunch of (playlistid, trackid) pairs in the
map table that don't refer to a valid playlist anymore.

Signed-off-by: Anna Schumaker <Anna@NoWheyCreamery.com>

db/genre.py

@@ -25,7 +25,9 @@ class Genre(playlist.MappedPlaylist):
         playlist.MappedPlaylist.__init__(self, row, "emblem-generic", "genre_map")
         self._name = row["name"]
 
-    def delete(self): Table.delete(self)
+    def delete(self):
+        self.clear()
+        Table.delete(self)
 
     @GObject.Property
     def name(self): return self._name

db/playlist.py

@@ -50,6 +50,10 @@ class MappedPlaylist(Playlist):
                           f"({self.rowkey}, trackid) VALUES (?, ?)",
                             [ self.rowid, track.rowid ]).rowcount == 1
 
+    def clear(self):
+        sql.execute(f"DELETE FROM {self.map_table} "
+                    f"WHERE {self.rowkey}=?", [ self.rowid ])
+
     def get_n_tracks(self):
         cur = sql.execute(f"SELECT COUNT(*) FROM {self.map_table} "
                           f"WHERE {self._rowkey}=?", [ self._rowid ])

db/test_genre.py

@@ -19,8 +19,11 @@ class TestGenre(unittest.TestCase):
         self.assertEqual(genre.get_property("map-table"), "genre_map")
 
     def test_delete(self):
+        track = db.make_fake_track(1, 1, "Test Track", "/a/b/c/1.ogg")
         genre = db.genre.Table.find("Test Genre")
+        genre.add_track(track)
         genre.delete()
+        self.assertEqual(genre.get_n_tracks(), 0)
         self.assertIsNone(db.genre.Table.lookup("Test Genre"))
 
     def test_add_remove_track(self):

db/test_user.py

@@ -157,8 +157,11 @@ class TestUserPlaylist(unittest.TestCase):
         self.assertFalse(plist.plist_state.loop)
 
     def test_delete(self):
+        track = db.make_fake_track(1, 1, "Test Track", "/a/b/c/1.ogg")
         plist = db.user.Table.find("Test Playlist")
+        plist.add_track(track)
         plist.delete()
+        self.assertEqual(plist.get_n_tracks(), 0)
         self.assertIsNone(db.user.Table.lookup("Test Playlist"))
 
     def test_add_remove_track(self):

db/user.py

@@ -35,7 +35,9 @@ class UserPlaylist(playlist.MappedPlaylist):
         playlist.MappedPlaylist.__init__(self, row, icon_name, map_table)
         self._name = row["name"]
 
-    def delete(self): Table.delete(self)
+    def delete(self):
+        self.clear()
+        Table.delete(self)
 
     @GObject.Property
     def name(self): return self._name