Flutter how to save list data locally
To do this you'll certainly have to use the path_provider package with this tutorial on the flutter.dev website. You should then be able to register a file and read it at the start of your application.
Once you have imported the path_provider and the dart:io packages, you can do something like this :
final directory = await getApplicationDocumentsDirectory();
final File file = File('${directory.path}/jsonObjects.json');
if (await file.exists()) {
json = await file.readAsString();
} else {
file.writeAsString(json);
}
First you get the application document directory ( the path ), then you create a File with the right path. Then if the file already exist, you read it, else you create it with the json you got and you should be good to go !
Debankush Mridha
Updated on December 23, 2022Comments
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Debankush Mridha over 1 year
I am building a to-do list app and I would like to store the data locally such that every time I open the app, I get all the tasks that I had created previously. I am new to flutter and this is my first app. I already tried saving the data to a file, creating a JSON file to save the data and tried using a database. Nothing seems to work. Can someone help me with this?
This is my code: -
import 'package:flutter/material.dart'; class toDoList extends StatefulWidget { bool data = false; @override createState() { return new toDoListState(); } } class toDoListState extends State<toDoList> { List<String> tasks = []; List<bool> completedTasks = []; List<String> descriptions = []; List<bool> importance = []; @override Widget build(BuildContext context) { return new Scaffold ( body: buildToDoList(), floatingActionButton: new FloatingActionButton ( onPressed: addToDoItemScreen, tooltip: 'Add Task', child: new Icon(Icons.add), ), ); } Widget buildToDoList() { return new ListView.builder ( itemBuilder: (context, index) { if(index < tasks.length) { if(tasks[index] == "#45jiodg{}}{OHU&IEB") { tasks.removeAt(index); descriptions.removeAt(index); importance.removeAt(index); } return row(tasks[index], descriptions[index], index); }; }, ); } Widget row(String task, String description, int index) { return Dismissible( key: UniqueKey(), background: Container(color: Colors.red, child: Align(alignment: Alignment.center, child: Text('DELETE', textAlign: TextAlign.center, style: TextStyle(color: Colors.white, fontSize: 18),))), direction: DismissDirection.horizontal, onDismissed: (direction) { setState(() { tasks.removeAt(index); if(completedTasks[index]) { completedTasks.removeAt(index); } descriptions.removeAt(index); importance.removeAt(index); }); Scaffold.of(context).showSnackBar(SnackBar(content: Text(task+" dismissed"))); }, child: CheckboxListTile( controlAffinity: ListTileControlAffinity.leading, title: Text(task, style: (completedTasks[index]) ? TextStyle(decoration: TextDecoration.lineThrough) : TextStyle(),), subtitle: Text(descriptions[index], style: (completedTasks[index]) ? TextStyle(decoration: TextDecoration.lineThrough) : TextStyle(),), isThreeLine: true, secondary: (importance[index])? Icon(Icons.error, color: Colors.red,) : Text(''), value: completedTasks[index], onChanged: (bool value) { setState(() { if(completedTasks[index]) { completedTasks[index] = false; } else { completedTasks[index] = true; } }); }, )); } void addToDoItemScreen() { int index = tasks.length; while (importance.length > tasks.length) { importance.removeLast(); } importance.add(false); tasks.add("#45jiodg{}}{OHU&IEB"); descriptions.add("No Description"); completedTasks.add(false); Navigator.of(context).push(new MaterialPageRoute(builder: (context) { return StatefulBuilder(builder: (context, setState) { // this is new return new Scaffold( appBar: new AppBar(title: new Text('Add a new task')), body: Form( child: Column( children: <Widget>[ TextField( autofocus: true, onSubmitted: (name) { addToDoItem(name); //Navigator.pop(context); // Close the add todo screen }, decoration: new InputDecoration( hintText: 'Enter something to do...', contentPadding: const EdgeInsets.all(20.0), border: OutlineInputBorder()), ), TextField( //autofocus: true, //enabled: descriptions.length > desc, onSubmitted: (val) { addDescription(val, index); }, decoration: new InputDecoration( hintText: 'Enter a task decription...', contentPadding: const EdgeInsets.all(20.0), border: OutlineInputBorder()), ), Row( children: <Widget> [ Switch( value: importance[index], onChanged: (val) { setState(() { }); impTask(index); }, ), Text('Important Task', style: TextStyle(fontSize: 18)), ], ), RaisedButton(onPressed: () { Navigator.pop(context); }, child: Text('DONE', style: TextStyle(fontSize: 20)),) ], ), )); }); })); } void addToDoItem(String task) { setState(() { tasks.last = task; }); } void addDescription(String desc, int index) { setState(() { descriptions.last = desc; }); } void impTask(int index) { setState(() { if(importance[index]) { importance[index] = false; } else { importance[index] = true; } }); } }
I have 4 lists with the data. I need a simple way to save the lists such that the next time I open the app, the lists retain the data that was saved in them, the last time I had closed the app.