How to use data stored in Shared Preferences in Text Widget for Flutter-CodePudding

I am trying to display the name of a project in a new page, as a string that I had saved in a previous page using Shared Preferences. Below is the section of code where I saved this:

 onPressed: () async {
                                            SharedPreferences localStorage =
                                                await SharedPreferences
                                                    .getInstance();
                                            localStorage.setString(
                                                'project_id', nDataList.id);
                                            localStorage.setString(
                                                'project_name',
                                                nDataList.title);
                                            localStorage.setString(
                                                'project_desc',
                                                nDataList.description);
                                            localStorage.setString(
                                                'project_due',
                                                nDataList.endDate);
                                            // ignore: use_build_context_synchronously
                                            Navigator.pushNamed(
                                                context, 'activities');
                                          },
                                        )

In the new page, I am using the get string in a function and then I want to display the result in a text widget. Here is all the code for the second page:

import 'package:flutter/material.dart';
import 'package:mne/Actual Tasks/activity_widget.dart';
import 'package:mne/UserTasks/task_widget.dart';
import 'package:shared_preferences/shared_preferences.dart';

class ProjectTask extends StatefulWidget {
  const ProjectTask({Key key}) : super(key: key);

  @override
  State<ProjectTask> createState() => _ProjectTaskState();
}

class _ProjectTaskState extends State<ProjectTask> {

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


  Future<Null> _fetchData() async {
    WidgetsFlutterBinding.ensureInitialized();
    SharedPreferences localStorage = await SharedPreferences.getInstance();
    var pname = localStorage.getString('project_name');
    var pdesc = localStorage.getString('project_desc');
    var pdue = localStorage.getString('project_due');
  }

 

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
          automaticallyImplyLeading: true,
          centerTitle: true,
          title: const Text('Project Details')),
      body: SingleChildScrollView(
        child: Column(children: [
          // for image
          Container(
            child: Image.asset('assets/images/projectbanner.png'),
          ),
          //for project name
          Container(
              child: Row(children: [
            Container(
                padding: const EdgeInsets.only(right: 10, top: 8),
                child: const Icon(Icons.calendar_month_outlined)),
            RichText(
                text: TextSpan(children: [
              TextSpan(
                  text: 'Due: ',
                  style: TextStyle(
                      fontSize: 14,
                      fontWeight: FontWeight.bold,
                      color: Colors.black)),
              TextSpan(
                  text: '$pname',
                  style: TextStyle(fontSize: 14, color: Colors.black))
            ])),
          ])),
          // for description title
          Container(child: const Text('Description')),
          // for actual desc
          Container(),
          // for task title
          Container(),
          // for task widget
          Container(height: 630, child: const ActivityWidget()),
        ]),
      ),
    );
  }
}

The error that I am getting says that 'pname' is undefined and that it is of type dynamic. How can I use the information saved in the variable in the text widget? Any help is much appreciated

CodePudding user response：

Try this:

class ProjectTask extends StatefulWidget {
  const ProjectTask({Key key}) : super(key: key);

  @override
  State<ProjectTask> createState() => _ProjectTaskState();
}

class _ProjectTaskState extends State<ProjectTask> {

  String pname;
  String pdesc;
  String pdue;
  
  @override
  void initState() {
    super.initState();
    _fetchData();
  }

  Future<Null> _fetchData() async {
    WidgetsFlutterBinding.ensureInitialized();
    SharedPreferences localStorage = await SharedPreferences.getInstance();
    setState(() {
      pname = localStorage.getString('project_name');
      pdesc = localStorage.getString('project_desc');
      pdue = localStorage.getString('project_due');
    });
  }



  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
          automaticallyImplyLeading: true,
          centerTitle: true,
          title: const Text('Project Details')),
      body: SingleChildScrollView(
        child: Column(children: [
          // for image
          Container(
            child: Image.asset('assets/images/projectbanner.png'),
          ),
          //for project name
          Container(
              child: Row(children: [
                Container(
                    padding: const EdgeInsets.only(right: 10, top: 8),
                    child: const Icon(Icons.calendar_month_outlined)),
                RichText(
                    text: TextSpan(children: [
                      TextSpan(
                          text: 'Due: ',
                          style: TextStyle(
                              fontSize: 14,
                              fontWeight: FontWeight.bold,
                              color: Colors.black)),
                      TextSpan(
                          text: '$pname',
                          style: TextStyle(fontSize: 14, color: Colors.black))
                    ])),
              ])),
          // for description title
          Container(child: const Text('Description')),
          // for actual desc
          Container(),
          // for task title
          Container(),
          // for task widget
          Container(height: 630, child: const ActivityWidget()),
        ]),
      ),
    );
  }
}

CodePudding user response：

Try this

 class ProjectTask extends StatefulWidget {
  const ProjectTask({Key key}) : super(key: key);

  @override
  State<ProjectTask> createState() => _ProjectTaskState();
}

class _ProjectTaskState extends State<ProjectTask> {

  String pname;
  String pdesc;
  String pdue;
  
  @override
  void initState() {
    super.initState();
WidgetsBinding.instance.addPostFrameCallback((timeStamp) async {
      await _fetchData();
    });
  }

  Future<Null> _fetchData() async {
    WidgetsFlutterBinding.ensureInitialized();
    SharedPreferences localStorage = await SharedPreferences.getInstance();
    setState(() {
      pname = localStorage.getString('project_name');
      pdesc = localStorage.getString('project_desc');
      pdue = localStorage.getString('project_due');
    });
  }



  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
          automaticallyImplyLeading: true,
          centerTitle: true,
          title: const Text('Project Details')),
      body: SingleChildScrollView(
        child: Column(children: [
          // for image
          Container(
            child: Image.asset('assets/images/projectbanner.png'),
          ),
          //for project name
          Container(
              child: Row(children: [
                Container(
                    padding: const EdgeInsets.only(right: 10, top: 8),
                    child: const Icon(Icons.calendar_month_outlined)),
                RichText(
                    text: TextSpan(children: [
                      TextSpan(
                          text: 'Due: ',
                          style: TextStyle(
                              fontSize: 14,
                              fontWeight: FontWeight.bold,
                              color: Colors.black)),
                      TextSpan(
                          text: '${pname??''}',
                          style: TextStyle(fontSize: 14, color: Colors.black))
                    ])),
              ])),
          // for description title
          Container(child: const Text(pdesc??'')),
          // for actual desc
          Container(),
          // for task title
          Container(),
          // for task widget
          Container(height: 630, child: const ActivityWidget()),
        ]),
      ),
    );
  }
}