db: Create a database Row base class

This will be shared between settings, playlists, and tracks so we have a
common interface for working with database rows.

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

emmental/db/table.py

@@ -0,0 +1,33 @@
+# Copyright 2022 (c) Anna Schumaker
+"""Base classes for database objects."""
+from gi.repository import GObject
+from gi.repository import Gio
+
+
+class Row(GObject.GObject):
+    """A single row in a database table."""
+
+    table = GObject.Property(type=Gio.ListModel)
+
+    def __init__(self, table: Gio.ListModel, **kwargs):
+        """Initialize a database Row."""
+        super().__init__(table=table, **kwargs)
+        self.connect("notify", self.__notify)
+
+    def __notify(self, row: GObject.GObject, param: GObject.ParamSpec) -> None:
+        match param.name:
+            case "table": pass
+            case _: self.do_update(param.name)
+
+    def do_update(self, column: str) -> bool:
+        """Update a Row in the database."""
+        return self.table.update(self, column, self.get_property(column))
+
+    def delete(self) -> bool:
+        """Delete this Row."""
+        return self.table.delete(self)
+
+    @property
+    def primary_key(self) -> None:
+        """Get the primary key for this row."""
+        raise NotImplementedError

tests/db/test_table.py

@@ -0,0 +1,47 @@
+# Copyright 2022 (c) Anna Schumaker
+"""Tests our database object base classes."""
+import unittest
+import unittest.mock
+import emmental.db.table
+import tests.util.table
+from gi.repository import GObject
+from gi.repository import Gio
+
+
+class TestRow(unittest.TestCase):
+    """Tests our common database Row object."""
+
+    def setUp(self):
+        """Set up common variables."""
+        self.table = Gio.ListStore()
+        self.table.delete = unittest.mock.Mock(return_value=True)
+        self.table.update = unittest.mock.Mock(return_value=True)
+        self.row = tests.util.table.MockRow(table=self.table)
+
+    def test_init(self):
+        """Test that the database Row is configured correctly."""
+        self.assertIsInstance(self.row, emmental.db.table.Row)
+        self.assertIsInstance(self.row, GObject.GObject)
+        self.assertEqual(self.row.table, self.table)
+
+    def test_primary_key(self):
+        """Test the primary_key property."""
+        with self.assertRaises(NotImplementedError):
+            emmental.db.table.Row(self.table).primary_key
+
+        self.row.number = 2
+        self.assertEqual(self.row.primary_key, 2)
+
+    def test_do_update(self):
+        """Test updating a Row attribute."""
+        self.row.number = 1
+        self.table.update.assert_called_with(self.row, "number", 1)
+
+        self.table.update.reset_mock()
+        self.row.table = None
+        self.table.update.assert_not_called()
+
+    def test_delete(self):
+        """Test deleting a Row."""
+        self.assertTrue(self.row.delete())
+        self.table.delete.assert_called_with(self.row)

tests/util/table.py

@@ -0,0 +1,15 @@
+# Copyright 2023 (c) Anna Schumaker.
+"""Mock Row and Table objects for testing."""
+import emmental.db.table
+from gi.repository import GObject
+
+
+class MockRow(emmental.db.table.Row):
+    """A fake Row customized for testing."""
+
+    number = GObject.Property(type=int)
+
+    @property
+    def primary_key(self) -> int:
+        """Get the primary key for this MockRow."""
+        return self.number