db: Give the database a 'loaded' property

This can be checked or connected to so other parts of the application
can easily know if all database tables have been loaded or not.

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

emmental/db/__init__.py

@@ -26,6 +26,7 @@ class Connection(connection.Connection):
     """Connect to the database."""
 
     active_playlist = GObject.Property(type=playlist.Playlist)
+    loaded = GObject.Property(type=bool, default=False)
 
     def __init__(self):
         """Initialize a sqlite connection."""
@@ -44,6 +45,12 @@ class Connection(connection.Connection):
 
         self.tracks = tracks.Table(self)
 
+    def __check_loaded(self) -> None:
+        for tbl in list(self.playlist_tables()) + [self.tracks]:
+            if tbl.loaded is False:
+                return
+        self.loaded = True
+
     def __check_version(self) -> None:
         user_version = self("PRAGMA user_version").fetchone()["user_version"]
         match user_version:
@@ -99,3 +106,4 @@ class Connection(connection.Connection):
     def table_loaded(self, tbl: table.Table) -> None:
         """Signal that a table has been loaded."""
         tbl.loaded = True
+        self.__check_loaded()

tests/db/test_db.py

@@ -72,22 +72,34 @@ class TestConnection(tests.util.TestCase):
 
     def test_load(self):
         """Check that calling load() loads the tables."""
-        idle_tables = [tbl for tbl in self.sql.playlist_tables()] + \
-                      [self.sql.tracks]
+        plist_tables = list(self.sql.playlist_tables())
+        all_tables = [self.sql.settings] + plist_tables + [self.sql.tracks]
 
         table_loaded = unittest.mock.Mock()
         self.sql.connect("table-loaded", table_loaded)
 
+        self.assertFalse(self.sql.loaded)
+        notify_loaded = unittest.mock.Mock()
+        self.sql.connect("notify::loaded", notify_loaded)
+
         self.sql.load()
         self.assertTrue(self.sql.settings.loaded)
-        for tbl in idle_tables:
+        notify_loaded.assert_not_called()
+
+        for tbl in all_tables[1:]:
             self.assertFalse(tbl.loaded)
-        for tbl in idle_tables:
+        for tbl in plist_tables:
             tbl.queue.complete()
             self.assertTrue(tbl.loaded)
+            self.assertFalse(self.sql.loaded)
+            notify_loaded.assert_not_called()
 
-        calls = [unittest.mock.call(self.sql, tbl)
-                 for tbl in [self.sql.settings] + idle_tables]
+        self.sql.tracks.queue.complete()
+        self.assertTrue(self.sql.tracks.loaded)
+        self.assertTrue(self.sql.loaded)
+        notify_loaded.assert_called()
+
+        calls = [unittest.mock.call(self.sql, tbl) for tbl in all_tables]
         table_loaded.assert_has_calls(calls)
 
     def test_filter(self):