How to set up sqlite database in flutter with null safety?

Question

I've been struggling for a while to set up a sqlite database with sqflite in flutter. Code is producing a new instance of the database every time I call the getter method for a database. Here is the code:

class DatabaseProvider {
  DatabaseProvider._();
  static final DatabaseProvider dbProvider = DatabaseProvider._();

  static Database? _database;

  Future<Database> get database async => _database ??= await _createDatabase();
}
...

what _createDatabase() do in your code? Does it initialize the _database ? — ישו אוהב אותך
– ישו אוהב אותך, Commented Dec 14, 2021 at 18:38
Yes, it's opening database with await openDatabase() and returning Future<Database> — Mayketi
– Mayketi, Commented Dec 14, 2021 at 18:41
then, did you set the returned object to _database?, something like: _database = await openDatabase()? — ישו אוהב אותך
– ישו אוהב אותך, Commented Dec 14, 2021 at 18:57
I didn't set returned object to _database because _database is assigned to _createDatabase() and that function is returning Database object. I tried to change getter method to if (_database != null) return _database! and _database = await _createDatabase(). But still same. Every time I try to insert to database I get new database instance with only one entry. — Mayketi
– Mayketi, Commented Dec 14, 2021 at 19:12
How about: Future<Database> get database async { if (_database == null) { _database = await _createDatabase(); } return _database; } ? — ישו אוהב אותך
– ישו אוהב אותך, Commented Dec 14, 2021 at 20:08

ישו אוהב אותך · Accepted Answer · 2021-12-14 21:22:24Z

1

You need to initialize the _database in your getter. So, change it to this:

Future<Database> get database async {
  if (_database == null) {
     // initialize database from _createDatabase result.
    _database = await _createDatabase();
  }
  // because _database have beeen initialized above, 
  // then we can use ! to tell that the _database can't be null.
  return _database!;
}

answered Dec 14, 2021 at 21:22

ישו אוהב אותך

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lolelo Over a year ago

Can late be used in some way?

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