SqfliteDatabaseException (DatabaseException(database_closed)) - ios

Question

The two pages in the application are listed with database(sqlite). but when I want to switch between pages, I get such an error: SqfliteDatabaseException (DatabaseException(database_closed))
please help mee.. I don't understand why see this error.
import 'dart:async';
import 'dart:io';
import 'dart:typed_data';
import 'package:bankingapp/models/coin.dart';
import 'package:bankingapp/models/histories.dart';
import 'package:flutter/services.dart';
import 'package:sqflite/sqflite.dart';
import 'package:path/path.dart';
class DbHelper {
static Database? _db;
Future<Database> get db async {
return _db ??= await initDb();
}
Future<Database> initDb() async {
var dbFolder = await getDatabasesPath();
String path = join(dbFolder, 'app.db');
// Delete any existing database:
await deleteDatabase(path);
// Create the writable database file from the bundled demo database file:
try {
await Directory(dirname(path)).create(recursive: true);
} catch (_) {}
ByteData data =
await rootBundle.load(join("assets/database", "bankingapp.db"));
List<int> bytes =
data.buffer.asUint8List(data.offsetInBytes, data.lengthInBytes);
await new File(path).writeAsBytes(bytes, flush: true);
//open the database
return await openDatabase(path);
/*
var dbFolder = await getDatabasesPath();
String path = join(dbFolder, 'app.db');
return await openDatabase(path);*/
}
Future<List<Histories>> getHistories() async {
var dbClient = await db;
var result = await dbClient.rawQuery("SELECT * FROM Histories");
return result.map((data) => Histories.fromMap(data)).toList();
}
Future<List<Coins>> getCoins() async {
var dbClient = await db;
var result = await dbClient.rawQuery("SELECT * FROM Coins");
return result.map((data) => Coins.fromMap(data)).toList();
}
}

Answer 1

First, uninstall the app from the device and run flutter clean and then build a new app and run it again to see if the error occurs.
Then, check the device in which you are running your app has restricted your app or not, see if your device requires any particular permission.
If it still occurs according to your provided information it seems like the problem is either the database is getting closed or it's not opening it can be because of many reasons like not doing proper initialization or even just forgetting to put await. Check the database initialization code in which you are opening your database or not then check if you are by mistake closing the database somewhere, which should have been done only when the app is terminated.
If you have done both of the above steps correct check your database location and mapping.
If nothing is working please try to follow official sqflite docs and example, as your code seems different from the one shown in the plugin example.