Flutter shared prefernce return NULL-CodePudding

I have next piece of flutter code, to get shared preference key-value

I do understand why _blueUriInit is always NULL

CodePudding user response：

I assume that you are forgot to provide the value for that key before call to get its value, you need to first assign value to it first:

Future<bool> saveData(String key, dynamic value) async {
  final prefs = await SharedPreferences.getInstance();
  return prefs.setString(key, value);
}

and call it like this:

void initState() {
   saveData('blueUri', 'test');

   setState(() {
     _blueUriInit = getValue('blueUri');
   });
   super.initState();
}

now next time you open your app, getValue should return you test.

CodePudding user response：

you can create this function for setting value

static setUserID(String key, String value) async {
   final SharedPreferences preferences = await SharedPreferences.getInstance();
   preferences.setString(key, value);
}

Use case :

await SharedValue.setUserID("Email", "[email protected]");

And For getting value from shared preference you can use this function

static Future<String?> getUserID(String key) async {
    final SharedPreferences preferences = await SharedPreferences.getInstance();
    return preferences.getString(key);
}

Use case :

userName = await SharedValue.getUserID("Email");

CodePudding user response：

First you need to setString with key and value (name is key)

Future setValue() async {
  final prefs = await SharedPreferences.getInstance();
  prefs.setString("name", "Hitarth");
}

getString with key (here i took "name" as key)

Future getValue(String key) async {
  final prefs = await SharedPreferences.getInstance();
  String value = prefs.getString(key) ?? "NULL";
  return value;
}

store in variable callin getValue

void initState() {
  setState(() {
    _blueUriInit = getValue("name");
  });
  super.initState();
}