database.dart

import 'dart:io';
import 'package:sqflite/sqflite.dart';
import 'package:path_provider/path_provider.dart';
import 'package:path/path.dart';

class DBProvider {
    DBProvider._();

    static final DBProvider db = DBProvider._();
    Database _database;

    Future<Database> get database async {
        if (_database != null) {
            return _database;
        }

        _database = await initDB();
        return _database;
    }

    initDB() async {
        Directory documentsDir = await getApplicationDocumentsDirectory();
        String path = join(documentsDir.path, 'my_app.db');

        return await openDatabase(path, version: 1, onOpen: (db) {
        }, onCreate: (Database db, int version) async {
            await db.execute('''
                CREATE TABLE user(
                    id INTEGER PRIMARY KEY,
                    name TEXT NOT NULL
                )
            ''');
        });
    }
}