init method
init db
Implementation
@override
Future init({Directory? dir}) async {
if (_db != null) return;
dir ??= await getApplicationDocumentsDirectory();
await dir.create(recursive: true);
final dbPath = join(dir.path, '$dbName.db');
_db = await databaseFactoryIo.openDatabase(
dbPath,
version: 1,
onVersionChanged: (db, oldVer, newVer) {},
);
}