so basically this is my provider, what i want is how can i store the model data coming from provider to a shared preferences, and then how to decode it to show it in a bookmark page?

class bookmark extends ChangeNotifier{
  int _count = 0;
  List<bookmarkModel> bookM = [];
  
  void addCount(){
    _count  ;
   notifyListeners();
  }
  
  void addItems(bookmarkModel i){
   bookM.add(i);
   notifyListeners();
  }

  int get  count => _count;
  List<bookmarkModel> get  bookMList => bookM;

}

here is my model:

import 'package:flutter/cupertino.dart';

class bookmarkModel{
  String title;
  String subtitle;
  int ayahnum;

  bookmarkModel({this.title, this.subtitle, this.ayahnum});

  bookmarkModel.fromJson(Map<String,dynamic> json) :
  title = json['title'], 
  subtitle = json['sutitle'], 
  ayahnum = json['ayahnum'];

  Map<String, dynamic> toJson()=>{
    'title':title,
    'subtitle':subtitle,
    'ayahnum': ayahnum
  }; 
}

CodePudding user response：

SharedPreferences should only be used to store small and simple values. It's not meant to be used as a Database.

You can use sharedPreferences to store bool, String, int and simple Lists (not lists of objects or maps). As far as I know, it even cannot store doubles.

Try using a SQflite or Hive (No-SQL) to store more complex or extensive data locally.

CodePudding user response：

You already have toJosn and fromJson ready to use, you just need to convert bookM to a map josnEnode() and the get it back using josnDecode().

try the code below:

void saveBookmark() async{
    SharedPreferences prefs = await SharedPreferences.getInstance();
    final String List = jsonEncode(bookM, toEncodable: (c)=> c.toJson());        
    await prefs.setString('BookMarkList', List);
  }

  void loadBookMark() async{
    SharedPreferences prefs = await SharedPreferences.getInstance();
    final String saved = prefs.getString('BookMarkList');
    final List<dynamic> decoded = jsonDecode(saved);
    bookM = decoded.map((bookmark) => bookmarkModel.fromJson(bookmark));
  }