in my app i am generating forms dynamically, i want to store every form data to be stored locally so that i can use it in my app. i also want the form textfield to be filled autometically with the previous data the user has entered with initstate but i am unable to implemet it.

i am expecting to store each form data locally, to use that later. secondly i want the form fields to be filled when the app is opened with the data that user has entered previously.

CodePudding user response：

It would be more practical for you to generate a JSON from this form. This way it will save and retrieve only a single field. When retrieving the JSON you get a MAP there it's easy to find the field and restore its value. But, use it in moderation, pay attention to the limitations of the package

CodePudding user response：

You can save the data simply by storing it in the shared preference key-value store. When you can save data like this : -

pref.setString("userName", userName.text); 

In the above code, first parameter(userName) is the name of the shared preference variable and the second parameter(userName.text) is the value.

Data can be fetched in this way : -

userName.text = pref.getString("userName") ?? ''; // Pass the name of the variable

Latest shared_preferences version has some bugs in it hence use the stable version, shared_preferences: 2.0.0

Full Code : -

import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart'; // shared_preferences: 2.0.0

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

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Shared Preference',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      debugShowCheckedModeBanner: false,
      home: const SharedPreference(),
    );
  }
}

class SharedPreference extends StatefulWidget {
  const SharedPreference({Key? key}) : super(key: key);
  @override
  _SharedPreferenceState createState() => _SharedPreferenceState();
}

class _SharedPreferenceState extends State<SharedPreference> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: const Text("Shared Preference"),
          backgroundColor: Colors.green,
        ),
        body: Center(
          child: ElevatedButton(
            child: const Text("User's Data"),
            onPressed: () {
              Navigator.push(
                context,
                MaterialPageRoute(builder: (context) => const UserForm()),
              );
            },
          ),
        ));
  }
}

class UserForm extends StatefulWidget {
  const UserForm({Key? key}) : super(key: key);
  @override
  _UserFormState createState() => _UserFormState();
}

class _UserFormState extends State<UserForm> {
  TextEditingController userName = TextEditingController();
  TextEditingController userAge = TextEditingController();

  @override
  void initState() {
    super.initState();
    loadData();
  }

  loadData() {
    SharedPreferences.getInstance().then((pref) {
      setState(() {
        userName.text = pref.getString("userName") ?? '';
        userAge.text = pref.getString("userAge") ?? '';
      });
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: const Text("Shared Preference"),
          backgroundColor: Colors.green,
        ),
        body: Center(
          child: Padding(
            padding: const EdgeInsets.only(left: 20, right: 20),
            child: Column(
              mainAxisAlignment: MainAxisAlignment.center,
              crossAxisAlignment: CrossAxisAlignment.center,
              children: [
                TextField(
                  controller: userName,
                  decoration: const InputDecoration(hintText: 'Username'),
                ),
                const SizedBox(
                  height: 30,
                ),
                TextField(
                  controller: userAge,
                  decoration: const InputDecoration(hintText: 'Age'),
                ),
                const SizedBox(
                  height: 30,
                ),
                ElevatedButton(
                  child: const Text("Save"),
                  onPressed: () async {
                    Navigator.pop(context);
                    final pref = await SharedPreferences.getInstance();
                    pref.setString("userName", userName.text);
                    pref.setString("userAge", userAge.text);
                  },
                ),
              ],
            ),
          ),
        ));
  }
}