db: Add a base class for Playlist Objects

This object inherits from the table.Row base class. It adds in
properties for name, active state, and propertyid and a rename()
function for updating the Table sort order during a rename.

Additionally, child playlists can be enabled by calling add_children().
This will set up a Gtk.FilterListModel using the provide child Table and
Filter.

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

emmental/db/playlist.py

@@ -0,0 +1,43 @@
+# Copyright 2022 (c) Anna Schumaker
+"""A customized Gio.ListStore for tracking Playlist GObjects."""
+from gi.repository import GObject
+from gi.repository import Gio
+from gi.repository import Gtk
+from . import table
+
+
+class Playlist(table.Row):
+    """Our shared Playlist Row object."""
+
+    propertyid = GObject.Property(type=int)
+
+    name = GObject.Property(type=str)
+    active = GObject.Property(type=bool, default=False)
+
+    n_tracks = GObject.Property(type=int)
+
+    children = GObject.Property(type=Gtk.FilterListModel)
+
+    def __init__(self, table: Gio.ListModel, propertyid: int,
+                 name: str = "", active: bool = False, **kwargs):
+        """Initialize a Playlist object."""
+        super().__init__(table=table, propertyid=propertyid,
+                         name=name, active=active, **kwargs)
+
+    def add_children(self, child_table: table.Table,
+                     child_filter: Gtk.Filter) -> None:
+        """Create a FilterListModel for this playlist's children."""
+        self.children = Gtk.FilterListModel.new(child_table, child_filter)
+        self.children.set_incremental(True)
+
+    def do_update(self, column: str) -> bool:
+        """Update a Playlist object."""
+        match column:
+            case "propertyid" | "name" | "n-tracks" | "children": pass
+            case _: return super().do_update(column)
+        return True
+
+    @GObject.Property(type=table.Row)
+    def parent(self) -> table.Row | None:
+        """Get this playlist's parent playlist."""
+        return None

tests/db/test_playlist.py

@@ -0,0 +1,61 @@
+# Copyright 2022 (c) Anna Schumaker
+"""Tests our ListStore and Playlist objects."""
+import unittest
+import unittest.mock
+import emmental.db.playlist
+from gi.repository import Gio
+from gi.repository import Gtk
+
+
+class TestPlaylistRow(unittest.TestCase):
+    """Tests our shared Playlist Row."""
+
+    def setUp(self):
+        """Set up common variables."""
+        self.table = Gio.ListStore()
+        self.table.update = unittest.mock.Mock(return_value=True)
+        self.playlist = emmental.db.playlist.Playlist(table=self.table,
+                                                      propertyid=0)
+
+    def test_init(self):
+        """Test that the Playlist object is configured correctly."""
+        self.assertIsInstance(self.playlist, emmental.db.table.Row)
+        self.assertEqual(self.playlist.table, self.table)
+        self.assertEqual(self.playlist.propertyid, 0)
+        self.assertEqual(self.playlist.name, "")
+        self.assertEqual(self.playlist.n_tracks, 0)
+        self.assertFalse(self.playlist.active)
+
+        playlist2 = emmental.db.playlist.Playlist(table=self.table,
+                                                  propertyid=1,
+                                                  name="Test Name", active=1)
+        self.assertEqual(playlist2.propertyid, 1)
+        self.assertEqual(playlist2.name, "Test Name")
+        self.assertTrue(playlist2.active)
+
+    def test_children(self):
+        """Test the child playlist properties."""
+        self.assertIsNone(self.playlist.children)
+
+        filter = Gtk.Filter()
+        self.playlist.add_children(self.table, filter)
+        self.assertIsInstance(self.playlist.children, Gtk.FilterListModel)
+        self.assertEqual(self.playlist.children.get_filter(), filter)
+        self.assertEqual(self.playlist.children.get_model(), self.table)
+        self.assertTrue(self.playlist.children.get_incremental())
+
+    def test_parent(self):
+        """Test the parent playlist property."""
+        self.assertIsNone(self.playlist.parent)
+
+    def test_do_update(self):
+        """Test the do_update() function."""
+        for (prop, value) in [("name", "New Name"), ("propertyid", 12345),
+                              ("children", Gtk.FilterListModel()),
+                              ("n-tracks", 42)]:
+            with self.subTest(property=prop):
+                self.playlist.set_property(prop, value)
+                self.table.update.assert_not_called()
+
+        self.playlist.active = True
+        self.table.update.assert_called_with(self.playlist, "active", True)