+ id_type: type[Any] = int
+
+ @classmethod
+ def from_table_row(cls, db_conn: DatabaseConnection,
+ row: Row | list[Any]) -> Any:
+ """Make from DB row, write to DB cache."""
+ obj = cls(*row)
+ assert isinstance(obj.id_, cls.id_type)
+ cache = getattr(db_conn, f'cached_{cls.table_name}')
+ cache[obj.id_] = obj
+ return obj
+
+ @classmethod
+ def _by_id(cls,
+ db_conn: DatabaseConnection,
+ id_: int | str) -> tuple[Any, bool]:
+ """Return instance found by ID, or None, and if from cache or not."""
+ from_cache = False
+ obj = None
+ cache = getattr(db_conn, f'cached_{cls.table_name}')
+ if id_ in cache.keys():
+ obj = cache[id_]
+ from_cache = True
+ else:
+ for row in db_conn.exec(f'SELECT * FROM {cls.table_name} '
+ 'WHERE id = ?', (id_,)):
+ obj = cls.from_table_row(db_conn, row)
+ cache[id_] = obj
+ break
+ return obj, from_cache