[flutter] How to save to local storage using Flutter?

In Android, if I have the information I want to persist across sessions I know I can use SharedPreferences or create a SQLite database or even write a file to the device and read it in later.

Is there a way to save and restore data like this just using Flutter? Or would I need to write device-specific code for Android and iOS like in the services example?

There are a few options:

Moor: Persistence library for Dart

• https://pub.dev/packages/moor_flutter

Read and Write file

• https://flutter.io/reading-writing-files/

Shared preferences plugin for flutter

• https://pub.dev/packages/shared_preferences

SQlite for flutter

• https://pub.dev/packages/sqflite

If you are in a situation where you wanna save a small value that you wanna refer later. then you should store your data as key-value data using shared_preferences

• Storing key-value data on disk

but if you want to store large data you should go with SQLITE

• How to get Started with SQLITE in Flutter

however you can always use firebase database which is available offline

• how to add firebase to your flutter project
• Firebase for Flutter Codelab from google

Since we are talking about local storage you can always read and write files to the disk

• Reading and Writing Files

Other solutions :

• Simple Embedded Application Store database
• A Flutter plugin to store data in secure storage

If you need to store just simple values like API token or login data (not passwords!), here is what I used:

import 'package:shared_preferences/shared_preferences.dart';

asyncFunc() async { // Async func to handle Futures easier; or use Future.then
  SharedPreferences prefs = await SharedPreferences.getInstance();
}
...

// Set
prefs.setString('apiToken', token);

// Get
String token = prefs.getString('apiToken');

// Remove
prefs.remove('apiToken');

Don't forget to add shared_preferences dependency in your pubspec.yaml (preserve spacing format):

dependencies:

  shared_preferences: any

You can use shared preferences from flutter's official plugins. https://github.com/flutter/plugins/tree/master/packages/shared_preferences

It uses Shared Preferences for Android, NSUserDefaults for iOS.

I was looking for the same, simple local storage but also with a reasonable level of security. The two solutions I've found that make the most sense are flutter_secure_storage (as mentioned by Raouf) for the small stuff, and hive for larger datasets.

You can use Localstorage

1- Add dependency to pubspec.yaml (Change the version based on the last)

dependencies:
  ...
  localstorage: ^3.0.0

2- Then run the following command

flutter packages get

3- import the localstorage :

import 'package:localstorage/localstorage.dart';

4- create an instance

class MainApp extends StatelessWidget {
  final LocalStorage storage = new LocalStorage('localstorage_app');
  ...
}

Add item to lcoalstorage :

void addItemsToLocalStorage() {
  storage.setItem('name', 'Abolfazl');
  storage.setItem('family', 'Roshanzamir');

  final info = json.encode({'name': 'Darush', 'family': 'Roshanzami'});
  storage.setItem('info', info);
}

Get an item from lcoalstorage:

void getitemFromLocalStorage() {
  final name = storage.getItem('name'); // Abolfazl
  final family = storage.getItem('family'); // Roshanzamir
  
  Map<String, dynamic> info = json.decode(storage.getItem('info'));
  final info_name=info['name'];
  final info_family=info['family'];
}

Delete an item from localstorage :

void removeItemFromLocalStorage() {
  storage.deleteItem('name');
  storage.deleteItem('family');
  storage.deleteItem('info');
}

You can use SharedPreferences for small amount of data. But if you have large and complex data then you should use Sqlite Database for local storage in flutter applications.

A late answer but I hope it will help anyone visiting here later too..

I will provide categories to save and their respective best methods...

1. Shared Preferences Use this when storing simple values on storage e.g Color theme, app language, last scroll position(in reading apps).. these are simple settings that you would want to persist when the app restarts.. You could, however, use this to store large things(Lists, Maps, Images) but that would require serialization and deserialization.. To learn more on this deserialization and serialization go here.
2. Files This helps a lot when you have data that is defined more by you for example log files, image files and maybe you want to export csv files.. I heard that this type of persistence can be washed by storage cleaners once disk runs out of space.. Am not sure as i have never seen it.. This also can store almost anything but with the help of serialization and deserialization..
3. Saving to a database This is enormously helpful in data which is a bit complex. And I think this doesn't get washed up by disc cleaners as it is stored in AppData(for android).. In this, your data is stored in an SQLite database. Its plugin is SQFLite. Kinds of data that you might wanna put in here are like everything that can be represented by a database.

I think If you are going to store large amount of data in local storage you can use sqflite library. It is very easy to setup and I have personally used for some test project and it works fine.

https://github.com/tekartik/sqflite This a tutorial - https://proandroiddev.com/flutter-bookshelf-app-part-2-personal-notes-and-database-integration-a3b47a84c57

If you want to store data in cloud you can use firebase. It is solid service provide by google.

https://firebase.google.com/docs/flutter/setup