SharePreferences Handler
========================
I have created a `LocalStorageRepository` class, that is responsible to handle local data using `SharedPreferences`.
The class is dynamic and can work with any type of data (int, double, bool, String, and Object) using generics and JSON decoding and encoding.
In order to prevent pron errors, I added the `LocalStorageKeys` enum to handle the supported keys. Feel free to add more keys to that enum.
enum LocalStorageKeys { tutorialCompleted, user }
@singleton
class LocalStorageRepository {
const LocalStorageRepository(SharedPreferences prefs) : _prefs = prefs;
final SharedPreferences _prefs;
bool keyExists(String key) => _prefs.containsKey(key);
T? getValue<T>(
LocalStorageKeys key, [
T Function(Map<String, dynamic>)? fromJson,
]) {
switch (T) {
case int:
return _prefs.getInt(key.name) as T?;
case double:
return _prefs.getDouble(key.name) as T?;
case String:
return _prefs.getString(key.name) as T?;
case bool:
return _prefs.getBool(key.name) as T?;
default:
assert(fromJson != null, 'fromJson must be provided for Object values');
if (fromJson != null) {
final stringObject = _prefs.getString(key.name);
if (stringObject == null) return null;
final jsonObject = jsonDecode(stringObject) as Map<String, dynamic>;
return fromJson(jsonObject);
}
}
return null;
}
void setValue<T>(LocalStorageKeys key, T value) {
switch (T) {
case int:
_prefs.setInt(key.name, value as int);
break;
case double:
_prefs.setDouble(key.name, value as double);
break;
case String:
_prefs.setString(key.name, value as String);
break;
case bool:
_prefs.setBool(key.name, value as bool);
break;
default:
assert(
value is Map<String, dynamic>,
'value must be int, double, String, bool or Map<String, dynamic>',
);
final stringObject = jsonEncode(value);
_prefs.setString(key.name, stringObject);
}
}
}
In case you want to get an Object value from `LocalStorageRepository`, you will need to provide its `fromJson` decoder.
final user = _localStorage.getValue(LocalStorageKeys.user, User.fromJson);
Hope that hence example will help others out there.
Feel free to edit this question and suggest any changes.