Flutter Shared Preferences Helper

shared_preferences.dart

import 'package:online_tpi_qms_mobile/model/user/user.dart';
import 'dart:convert';
import 'package:shared_preferences/shared_preferences.dart';

class SharedPrefs {
  static SharedPreferences _sharedPrefs;
  static Map<String, dynamic> _memoryPrefs = Map<String, dynamic>();

  factory SharedPrefs() => SharedPrefs._internal();

  SharedPrefs._internal();

  Future<void> init() async {
    _sharedPrefs ??= await SharedPreferences.getInstance();
    // We deleted the before user data because of we don't hold sessions.
    removeUserData();
  }

  // ---------------------------
  // User
  // ---------------------------

  final String userKey = "user";

  Future<void> setUser(User user) async {
    _memoryPrefs[userKey] = jsonEncode(user);
    await _sharedPrefs.setString(userKey, jsonEncode(user));
  }

  User getUser() {
    String userMap;
    User user;

    if (_memoryPrefs.containsKey(userKey)) {
      userMap = _sharedPrefs.getString(userKey);
      if (userMap != null) user = User.fromJson(json.decode(userMap));
    }

    if (user == null) {
      userMap = _sharedPrefs.getString(userKey);
      if (userMap != null) user = User.fromJson(json.decode(userMap));
    }

    return user;
  }

  // ---------------------------
  // General Shared Preferences Helper
  // ---------------------------

  // String
  static void setString(String key, String value) {
    _memoryPrefs[key] = value;
    _sharedPrefs.setString(key, value);
  }

  static String getString(String key, {String defaultValue}) {
    String value;

    if (_memoryPrefs.containsKey(key)) value = _memoryPrefs[key];

    if (value == null) value = _sharedPrefs.getString(key);

    if (value == null) value = defaultValue;

    return value;
  }

  // Int
  static void setInt(String key, int value) {
    _memoryPrefs[key] = value;
    _sharedPrefs.setInt(key, value);
  }

  static int getInt(String key, {int defaultValue}) {
    int value;

    if (_memoryPrefs.containsKey(key)) value = _memoryPrefs[key];

    if (value == null) value = _sharedPrefs.getInt(key);

    if (value == null) value = defaultValue;

    return value;
  }

  // Bool
  static void setBool(String key, bool value) {
    _memoryPrefs[key] = value;
    _sharedPrefs.setBool(key, value);
  }

  static bool getBool(String key, {bool defaultValue = false}) {
    bool value;

    if (_memoryPrefs.containsKey(key)) value = _memoryPrefs[key];

    if (value == null) value = _sharedPrefs.getBool(key);

    if (value == null) value = defaultValue;

    return value;
  }

  // Double
  static void setDouble(String key, double value) {
    _memoryPrefs[key] = value;
    _sharedPrefs.setDouble(key, value);
  }

  static double getDouble(String key, {double defaultValue}) {
    double value;

    if (_memoryPrefs.containsKey(key)) value = _memoryPrefs[key];

    if (value == null) value = _sharedPrefs.getDouble(key);

    if (value == null) value = defaultValue;

    return value;
  }

  // Remove user data before log-out etc.
  Future<void> removeUserData() async {
    await _sharedPrefs.remove(userKey);
  }
}