"LateInitializationError" - sql

Question

I'm having problems with the "non-nullable" and these errors when updated to last version.
I have this error message when run the app:
The following LateError was thrown building Builder:
LateInitializationError: Field '_rHelper#616106152' has not been initialized.
I'm trying to connect with sqlite, and this is Helper class:
class RHelper {
static late Database _database;
static late RHelper _rHelper;
RHelper._createInstance();
factory RHelper() {
if (_rHelper == null) {
_rHelper = RHelper._createInstance();
}
return _rHelper;
}
Future<Database> get database async {
if (_database == null) {
_database = await initializeDatabase();
}
return _database;
}
Future<Database> initializeDatabase() async {
var dir = await getDatabasesPath();
var path = dir + "Rminder.db";
var database =
await openDatabase(path, version: 1, onCreate: (db, version) {
db.execute('''
create table $tableReminder (
$colId integer primary key autoincrement,
$colName text not null,
$colDetails text,
$colSave int )
''');
});
return database;
}
and the initState Function:
I am just try to check if the database had initialized successfully or not!
void initState() async {
super.initState();
await helper
.initializeDatabase()
.then((value) => {print("------------donne?")}); }
Note: I also tried ".whenComplete()" but it doesn't worked!

Answer 1

You must declare
Database? _database;
RHelper? _rHelper;
instead of
static late Database _database;
static late RHelper _rHelper;
because these variables may contain null values (see your own code):
if (_rHelper == null) // <-------
Keyword late is used for non-nullable variables which will be initialized later (for example, in initState method).
UPDATE:
As _rHelper is nullable you must use ! (exclamation sign) to resolve nullable value into non-nullable value.
class RHelper {
factory RHelper() {
if (_rHelper == null) {
_rHelper = RHelper._createInstance();
}
return _rHelper!; // <--------------
}
RHelper._createInstance();
static RHelper? _rHelper;
}
P.S. Please read this article Understanding null safety.