How to save a list to shared preferences

Question

I want to save a list to shared preferences, but it doesn't work... The goal is to add data to the variable and save it.

This is the variable I want to save:

    var savedData = [
      {'date': 0, 'testNumber': 0},
    ];

And this is the code I tried for saving and receiving the variable:

 Future<void> saveDataTest() async {
    final prefs = await SharedPreferences.getInstance();
    await prefs.setStringList(
        'dataTest', savedData.map((i) => i.toString()).toList());
  }
    
 Future<String> getDataStringTest() async {
    final prefs = await SharedPreferences.getInstance();
    savedData =
     prefs.getStringList('dataTest').map((i) => int.parse(i)).toList();
    setState(() {});
  }

This is the error I get:

A value of type 'List<int>' can't be assigned to a variable of type 'List<Map<String, int>>'.
Try changing the type of the variable, or casting the right-hand type to 'List<Map<String, int>>'.

Answer 1

Try using jsonEncode and jsonDecode from import 'dart:convert';

Like so:

 Future<void> saveDataTest() async {
    final prefs = await SharedPreferences.getInstance();
    await prefs.setString("dataTest ", jsonEncode(savedData));
  }
    
 Future<String> getDataStringTest() async {
    final prefs = await SharedPreferences.getInstance();
    savedData = List.from(jsonDecode(prefs.getString("dataTest")));
    setState(() {});
  }