Flutter | How to store list of int in Shared preference

Question

Here I want to store all the Ids of product in shared preference. but here when I am storing id using setInt it will store only one Id and remove previous IDs so I want that all id needs to be stored in shared preference and how to get all those ids that are stored in shared preferences.

Here is the code I've tried

 unAuthAddCart(dynamic itemId) async {
    try {
      SharedPreferences pref = await SharedPreferences.getInstance();
      var unAuthItemId = pref.setInt('unAuthItemid', itemId);
      print(unAuthItemId);
      var abc = pref.getInt('unAuthItemid');
      print("UnAuth Itme Id $abc");

    } catch (e) {
      print(e);
      print("Something went Wrong in Particular Product Cart");
    }
  }

Tungstate

It's strange that there's a setStringList method but no setIntList – Ponytail

Answer 1

Currently, there is not any option to directly save the list of ints in Sharedpreferences. You can save the list of Strings in sharedpreferences.

The easiest way for your case is to convert your List<int> values to List<String> and store them.

Also, at the time of retrieval you can fetch the List<String> stored in shared prefs and convert it to your original List<int>

For Ex :

To store your list in shared prefs.

SharedPreferences prefs=await SharedPreferences.getInstance();

// your custom int list
List<int> mList=[0,1,2,3,4];

// convert your custom list to string list
List<String> stringsList=  mList.map((i)=>i.toString()).toList();

// store your string list in shared prefs                
prefs.setStringList("stringList", stringsList);

To retrieve & convert your stored string list to your original int list

SharedPreferences prefs=await SharedPreferences.getInstance();

// fetch your string list      
List<String> mList = (prefs.getStringList('stringList') ?? List<String>());

//convert your string list to your original int list
List<int> mOriginaList = mList.map((i)=> int.parse(i)).toList();

print(mOriginaList);

Forefoot

Thank you jay for your answer. right now I have one ItemId which i am getting from the product so when i click on add to cart button id needs to store in shared pref and then if i click on another product previous id needs to remain and the new id needs to store. – Tungstate

Answer 2

You can copy paste run full code below
You can
Step 1: Convert List<int> to List<String>
Step 2: Save with prefs.setStringList
Step 3: Get it back with prefs.getStringList
Step 4: Covert to List<int>

code snippet

List<int> intProductListOriginal = [11, 22, 33, 44, 55];

  void _incrementCounter() async {
    List<String> strList = intProductListOriginal.map((i) => i.toString()).toList();
    SharedPreferences prefs = await SharedPreferences.getInstance();
    prefs.setStringList("productList", strList);

    List<String> savedStrList = prefs.getStringList('productList');
    List<int> intProductList = savedStrList.map((i) => int.parse(i)).toList();

    print("${intProductList.toString()}");

Output

I/flutter ( 4347): [11, 22, 33, 44, 55]

full code

import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;
  List<int> intProductListOriginal = [11, 22, 33, 44, 55];

  void _incrementCounter() async {
    List<String> strList = intProductListOriginal.map((i) => i.toString()).toList();
    SharedPreferences prefs = await SharedPreferences.getInstance();
    prefs.setStringList("productList", strList);

    List<String> savedStrList = prefs.getStringList('productList');
    List<int> intProductList = savedStrList.map((i) => int.parse(i)).toList();

    print("${intProductList.toString()}");

    setState(() {
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.headline4,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ),
    );
  }
}

Canicular

Answer 3

As long as you can encode your data with JSON (and if it doesn't work out of the box, you can provide your own converters, but an array of ints does work), you can store it practically directly:

await prefs.setString('yourname', json.encode(yourvar));

and read it back:

final list = json.decode(prefs.getString('yourname') ?? '[]');

Breathing