sharedp references Getting Stored Data in Another Flutter Page - flutter

Question

I want to get user details such as id, email, username in my HomePage when the user login into the login page. I was able to get the data via this
SPUtil.putString('user', user);
print(user);
Now, the issue is how should I pick it up in another page for usage or display those data. I have a file called sputils.dart where all the code that I used to get the data.
class AuthService {
Future<String> login({
required String username,
required String password,
}) async {
try {
final body = {
'username': username,
'password': password,
};
final response = await http.post(
Uri.parse('$BASE_URL/login'),
headers: {'Content-Type': 'application/json; charset=UTF-8'},
body: jsonEncode(body),
);
if (response.statusCode != 200) {
throw LoginError.unexpected;
}
Map<String, dynamic> data = jsonDecode(response.body);
User loggedInUser = User.fromJson(data['user']);
String user = jsonEncode(loggedInUser);
SPUtil.putString('user', user);
print(user);
return jsonDecode(response.body)['token'];
} on LoginError {
print('login error');
rethrow;
} catch (e) {
print(e);
throw LoginError.unexpected;
}
}
import 'dart:async';
import 'dart:convert';
import 'package:shared_preferences/shared_preferences.dart';
import 'package:synchronized/synchronized.dart';
// SharedPreferences
class SPUtil {
static SPUtil? _singleton;
static SharedPreferences? _prefs;
static final Lock _lock = Lock();
static Future<SPUtil> getInstance() async {
if (_singleton == null) {
await _lock.synchronized(() async {
if (_singleton == null) {
// keep local instance till it is fully initialized.
final singleton = SPUtil._();
await singleton._init();
_singleton = singleton;
}
});
}
return _singleton!;
}
SPUtil._();
Future _init() async {
_prefs = await SharedPreferences.getInstance();
}
// put object
static Future<bool> putObject(String key, Object value) {
return _prefs!.setString(key, json.encode(value));
}
// get string
static String getString(String key, {String defValue = ''}) {
if (_prefs == null) return defValue;
return _prefs!.getString(key) ?? defValue;
}
// put string
static Future<bool> putString(String key, String value) async {
return _prefs!.setString(key, value);
}
// get bool
static bool getBool(String key, {bool defValue = false}) {
if (_prefs == null) return defValue;
return _prefs!.getBool(key) ?? defValue;
}
// put bool
static Future<bool> putBool(String key, {bool value = false}) {
return _prefs!.setBool(key, value);
}
// get int
static int getInt(String key, {int defValue = 0}) {
if (_prefs == null) return defValue;
return _prefs!.getInt(key) ?? defValue;
}
// put int.
static Future<bool> putInt(String key, int value) {
return _prefs!.setInt(key, value);
}
// get double
static double getDouble(String key, {double defValue = 0.0}) {
if (_prefs == null) return defValue;
return _prefs!.getDouble(key) ?? defValue;
}
// put double
static Future<bool> putDouble(String key, double value) {
return _prefs!.setDouble(key, value);
}
// get string list
static List<String> getStringList(String key,
{List<String> defValue = const []}) {
if (_prefs == null) return defValue;
return _prefs!.getStringList(key) ?? defValue;
}
// put string list
static Future<bool> putStringList(String key, List<String> value) {
return _prefs!.setStringList(key, value);
}
// clear
static Future<bool> clear() {
return _prefs!.clear();
}
// clear a string
static Future<bool> clearString(String key) {
return _prefs!.remove(key);
}
//Sp is initialized
static bool isInitialized() {
return _prefs != null;
}
}

Answer 1

To use saved data from another page,
make your data instance to global(static)
save the data inside of static class
If your application is simple and just test something, go to No.1.
Or else, go to No.2.
make class static : https://dev.to/lucianojung/global-variable-access-in-flutter-3ijm
Using getController is easier to make it global : https://pub.dev/packages/get