Location to place Sqlite DB in Flutter

A Sqlite DB file has pre existing data, and this needs to be added to a Flutter application, ideally in a way which will work for both Android and iOS.

Have placed the file in the following location:

/assets/db/myDB.db

/assets is a folder in the root, like lib.

pubspec.yaml has:

 assets:
    - assets/db/

The code to open and query the database:

 final db = await openDatabase('myDb.db');

 final List<Map<String, dynamic>> maps = await db.rawQuery('SELECT * FROM mytable WHERE module_id = ?', [moduleId]);

An error is being thrown when trying to query the database, although none on opening the database. Even if I change the name of the db to one which does not exist, an error does not appear to be thrown. Tested this by using

await openDatabase('name.db')
          .catchError((e) => print('DB BERROR:' + e));

Nothing is printed.

What is the correct location to place the db file, so that it will be included when deployed on both Android and iOS?

Thanks

The assets is not really a folder in your filesystem.
In order to use it with sqlite, you need to copy the asset to a folder, typically the cache folder of your app.

Here is an example (add path_provider to your pubspec.yaml):

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

Future<Database> openDatabaseFromAssets() async {
  // Get the temporary directory (cache)
  final directory = await getTemporaryDirectory();
  final path = join(directory.path, 'myDB.db');
  
  // Check if the database file exists
  final exists = await File(path).exists();
  
  if (!exists) {
    // Copy from assets
    ByteData data = await rootBundle.load('assets/db/myDB.db');
    List<int> bytes = data.buffer.asUint8List(data.offsetInBytes, data.lengthInBytes);
    
    // Write and flush the bytes written
    await File(path).writeAsBytes(bytes, flush: true);
  }
  
  // Open the database
  return await openDatabase(path);
}