Storage

• Introduction to storage
• Storing and retrieving data
  • Store values
  • Retrieve values
• Storable models
  • Introduction to storable models
  • Saving a Storable model
  • Retrieve a Storable model
• Lightweight Storage
  • Backpack Storage
  • Persist Data with Backpack
• Storage keys

Introduction

In Nylo you can save data to the users device using the NyStorage class.

Under the hood, Nylo uses the flutter_secure_storage package to save and retrieve data.

Store values

To store values, you can use the below helper.

import 'package:nylo_framework/nylo_framework.dart';
...

NyStorage.store("com.company.myapp.coins", "10");

Data will persist on the user's device using NyStorage. E.g. if they exit the app, you can retrieve the same data that was stored previously.

Retrieve values

To retrieve values, you can use the below helper.

import 'package:nylo_framework/nylo_framework.dart';
...

// Default
String coins = await NyStorage.read("com.company.myapp.coins"); // 10

// String
String coins = await NyStorage.read<String>("com.company.myapp.coins"); // 10

// Integer
int coins = await NyStorage.read<int>("com.company.myapp.coins"); // 10

// double
double coins = await NyStorage.read<double>("com.company.myapp.coins"); // 10.00

Introduction to storable models

Storable models are handy for storing small-sized pieces of data on the user's device.

It's useful for storing information such as:

• Progress in a game
• API Token
• Locale preference

Here's a model that extends the Storable class.

class User extends Storable {
  String token;
  String username;
  String favouriteCity; 

  User({this.token, this.username, this.favouriteCity});

  @override
  toStorage() => {
      "token": this.token, 
      "username": this.username, 
      "favourite_city": this.favouriteCity
    };
  

  @override
  fromStorage(dynamic data) {
    this.token = data['token'];
    this.username = data['username'];
    this.favouriteCity = data['favourite_city'];
  }
}

After extending the Storable class, you then need to override the toStorage() and fromStorage methods.

• toStorage() - Creates the payload to be stored.

• fromStorage(dynamic data) - This will create the model from the data payload, the keys should match the toStorage() method.

Saving a Storable model

To save a Storable model, you can use the below helper.

import 'package:nylo_framework/nylo_framework.dart';
...

User user = new User();
user.username = "Anthony";

String key = "com.company.myapp.auth_user";

// saves to storage
user.save(key);

// or 

NyStorage.store(key, user);

Retrieve a Storable model

To retrieve a Storable model, you can use the below helper.

import 'package:nylo_framework/nylo_framework.dart';
...
String key = "com.company.myapp.auth_user";

User user = await NyStorage.read(key, model: new User());
print(user.username); // Anthony

Backpack Storage

Nylo includes a lightweight storage class called Backpack. This class is designed for storing small-sized pieces of data during a user's session.

The Backpack class isn't asynchronous so you can set/get data on the fly.

Here's the Backpack class in action.

Set data

// storing a string
Backpack.instance.set('user_api_token', 'a secure token');

// storing an object
User user = User();
Backpack.instance.set('user', user);

// storing an int
Backpack.instance.set('my_lucky_no', 7);

Read data

Backpack.instance.read('user_api_token'); // a secure token

Backpack.instance.read('user'); // User instance

Backpack.instance.read('my_lucky_no'); // 7

Real world usage

A great example for when you might want to use this class over the NyStorage class is when e.g. storing a user's api_token for authentication.

// login a user
LoginResponse loginResponse = await _apiService.loginUser('email': '...', 'password': '...');

String userToken = loginResponse.token;
// Store the user's token to NyStorage for persisted storage
await NyStorage.store('user_token', userToken);

// Store the token to the Backpack class to ensure the user is authenticated for subsequent API requests
Backpack.instance.set('user_token', userToken);

Now in our API Service, we can set the auth header from our Backpack class without having to wait on the async response.

class ApiService extends BaseApiService {
  ...
  Future<dynamic> accountDetails() async {
    return await network(
        request: (request) {
          String userToken = Backpack.instance.read('user_api_token');

          // Set auth header
          request.options.headers = {
            'Authorization': "Bearer " + userToken
          };
          
          return request.get("/account/1");
        },
    );
  }
}

Persist data with Backpack

You can use the NyStorage class to persist data but if you also need to save it to your App's Backpack storage, use the below parameter "inBackpack".

Here's an example.

// Store data in secure storage & in memory using Backpack
await NyStorage.store('user_token', 'a token 123', inBackpack: true);

// Fetch data back with Backpack
Backpack.instance.read('user_token'); // "a token 123"

By default, NyStorge will not store data in Backpack unless the inBackpack parameter is set to true

Storage Keys

This class is useful to reference Strings which you can later use in your NyStorage or Backpack class. You can use the StorageKey class to organise all the shared preference Strings in your project.

Open your Nylo project and open the "config/storage_keys.dart" file.

Please note. This file was added in Nylo v3.2.0, if it's missing, you can manually add it.

/*
|--------------------------------------------------------------------------
| Storage Keys
| Add your storage keys here and then use them later to retrieve data.
| E.g. static String userCoins = "USER_COINS";
| String coins = NyStorage.read( StorageKey.userCoins );
|
| Learn more: https://nylo.dev/docs/4.x/storage#storage-keys
|--------------------------------------------------------------------------
*/

class StorageKey {
  static String userToken = "USER_TOKEN";

  /// Add your storage keys here...

}

How to use in your project.

import 'package:flutter_app/config/storage_keys.dart';
...

class _MyHomePageState extends NyState<MyHomePage> {

  @override
  init() async {
    // Store
    await NyStorage.store( StorageKey.userToken , 'Anthony');

    // Retrieve
    String userName = await NyStorage.read( StorageKey.userToken );
  }

This simple class helps organise all your String keys for your Storage variables.