将快照数据从一个 dart 文件传递到 flutter 项目中的另一个文件

Question

In my flutter project their are 2 dart files. In the 1st dart page their is an initstate func that fetches snapshot data from firebase database[from line 19 onwards]. The first page is further routes to the second page[at line 71]. While routing it must also send the snapshot data to the 2nd dart page. In the second page the data is extracted from snapshot and used as initial value of the TextField in the 2nd dart page. Here is the code of both the dart file.

1st dart file:

import 'package:firebase_auth/firebase_auth.dart';
import 'package:firebase_database/firebase_database.dart';
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:flutter/widgets.dart';
import 'package:udharibook/Screens/UserProfile.dart';
import 'package:udharibook/services/authservice.dart';
import 'Customer_Support.dart';

class DashboardPage extends StatefulWidget {
  @override
  _DashboardPageState createState() => _DashboardPageState();
}

class _DashboardPageState extends State<DashboardPage> {

  String userName;
  @override
  void initState()
  {
    super.initState();
    FirebaseAuth _auth = FirebaseAuth.instance;
    DatabaseReference DBRef = FirebaseDatabase.instance.reference().child('Users');
    _auth.currentUser().then((curUser){
      DBRef.child(curUser.uid).once().then((DataSnapshot user){
        userName = user.value['Name'];
        setState(() {
          print('Username is:'+userName);
        });
      });
    });

  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('$userName'),
        backgroundColor: Color.fromRGBO(162, 42, 43, 1.0),
        actions: <Widget>[
          IconButton(
              icon: Icon(Icons.search),
              onPressed: () {
                print("Search Clicked");
              }),
          IconButton(
              icon: Icon(Icons.sort),
              onPressed: () {
                print("Sort Clicked");
              }),
        ],
      ),
      drawer: Drawer(
        child: ListView(
          children: <Widget>[
            DrawerHeader(
              child: Text('$userName'),
              decoration: BoxDecoration(
                color: Color.fromRGBO(162, 42, 43, 1.0),
              ),
            ),
            CustomMenu(
                Icons.person,
                'Profile',() => {

                      Navigator.pop(context),
                      Navigator.push(
                          context,
                          new MaterialPageRoute(
                              builder: (context) => UserProfile()))
                    }),
            CustomMenu(Icons.assessment, 'Reports', () => {}),
            CustomMenu(Icons.settings, 'Settings', () => {}),
            CustomMenu(
                Icons.perm_phone_msg,
                'Customer Support',
                () => {
                      Navigator.pop(context),
                      Navigator.push(
                          context,
                          new MaterialPageRoute(
                              builder: (context) => CustSupport()))
                    }),
            CustomMenu(Icons.lock, 'Log Out', () => {AuthService().signOut()}),
          ],
        ),
      ),
    );
  }
}

class CustomMenu extends StatelessWidget {
  IconData icon;
  String text;
  Function onTap;

  CustomMenu(this.icon, this.text, this.onTap);

  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return Padding(
        padding: EdgeInsets.fromLTRB(8.0, 0.0, 8.0, 0.0),
        child: Container(
            decoration: BoxDecoration(
                border:
                    Border(bottom: BorderSide(color: Colors.grey.shade400))),
            child: InkWell(
                splashColor: Colors.redAccent,
                onTap: onTap,
                child: Container(
                  height: 60.0,
                  child: Row(
                    mainAxisAlignment: MainAxisAlignment.spaceBetween,
                    children: <Widget>[
                      Row(
                        children: <Widget>[
                          Icon(icon),
                          Padding(
                              padding: const EdgeInsets.all(8.0),
                              child: Text(
                                text,
                                style: TextStyle(
                                    fontSize: 17.0, fontFamily: 'Exo2'),
                              )),
                        ],
                      ),
                      Icon(Icons.arrow_right),
                    ],
                  ),
                ))));
  }
}

2nd Dart file:

import 'dart:io';
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:flutter/widgets.dart';
import 'package:image_picker/image_picker.dart';
import 'package:firebase_storage/firebase_storage.dart';
import 'package:path/path.dart';

class UserProfile extends StatefulWidget {
  @override
  _UserProfileState createState() => _UserProfileState();
}
class _UserProfileState extends State<UserProfile> {
  File _image;
  TextEditingController nameController = TextEditingController(text: 'abc');
  TextEditingController mobileController = TextEditingController(text: '88888888');
  TextEditingController emailController =TextEditingController()..text='abc@gmail.com';
  TextEditingController addressController =TextEditingController()..text='India';

  @override
  Widget build(BuildContext context) {

    Future getImage() async{
      var image=await ImagePicker.pickImage(source: ImageSource.gallery);

      setState(() {
        _image=image;
        print('Image Path $_image');
      });
    }

    Future uploadPic(BuildContext context) async{

      String fileName = basename(_image.path);
      StorageReference firebaseStorageRef = FirebaseStorage.instance.ref().child(fileName);
      StorageUploadTask uploadTask = firebaseStorageRef.putFile(_image);
      StorageTaskSnapshot taskSnapshot = await uploadTask.onComplete;
      setState(() {
        print("Profile Picture Uploaded");
        Scaffold.of(context).showSnackBar(SnackBar(content:Text('Profile Updated')));
      });
    }
    return Scaffold(
      resizeToAvoidBottomPadding: false,
      appBar: AppBar(
        title: Text('User Profile'),
        backgroundColor: Color.fromRGBO(162, 42, 43, 1.0),
      ),
      body: Builder(
        builder: (context) => Container(
          child: Column(
            children: <Widget>[
              SizedBox(
                height: 20.0,
              ),
              Row(
                mainAxisAlignment: MainAxisAlignment.center,
                children: <Widget>[
                  Align(
                    alignment: Alignment.center,
                    child: CircleAvatar(
                      radius: 70,
                      backgroundColor: Colors.white,
                      child: ClipOval(
                        child: SizedBox(
                            height: 120.0,
                            width:120.0,
                            child:_image!=null?Image.file(_image,fit: BoxFit.fill):
                            Image.network(
                              'https://firebasestorage.googleapis.com/v0/b/udhari-book.appspot.com/o/DefaultImage.png?alt=media&token=06bddd3e-7f11-476b-a982-dfb21096f9c7',
                              fit: BoxFit.fitWidth,
                            ),
                        ),
                      ),
                    ),
                  ),
                  Padding(
                    padding: EdgeInsets.only( ),
                    child: IconButton(
                        icon: Icon(Icons.camera_alt), onPressed: () {
                          getImage();
                    }),
                  )
                ],
              ),
              Padding(
                  padding: EdgeInsets.only(top:20.0,left: 10.0,right: 10.0),
                  child:SizedBox(
                    height: 40.0,
                  child: TextField(
                    controller: nameController,
                    decoration: InputDecoration(
                        labelText: 'Full Name',
                        labelStyle:
                            TextStyle(fontFamily: 'Exo2', color: Colors.grey),
                        border: OutlineInputBorder(
                            borderRadius: BorderRadius.circular(5.0)
                        ),
                        focusedBorder: OutlineInputBorder(
                            borderRadius: BorderRadius.circular(5.0),
                            borderSide: BorderSide(
                                color:
                                Color.fromRGBO(162, 42, 43, 1.0)
                            )

                        )
                    ),
                  ),
              )),
              Padding(
                padding: EdgeInsets.only(top:15.0,left: 10.0,right: 10.0),
                child:SizedBox(
                  height: 40.0,
                child: TextField(
                  controller: mobileController,
                  enabled: false,
                  keyboardType:TextInputType.phone,
                  decoration: InputDecoration(
                      labelText: 'Mobile Number',
                      labelStyle:
                      TextStyle(fontFamily: 'Exo2', color: Colors.grey),
                      border: OutlineInputBorder(
                          borderRadius: BorderRadius.circular(5.0)),
                      focusedBorder: OutlineInputBorder(
                          borderRadius: BorderRadius.circular(5.0),
                          borderSide: BorderSide(
                              color:
                              Color.fromRGBO(162, 42, 43, 1.0)
                          )
                      )
                  ),
                ),
              )),
              Padding(
                padding: EdgeInsets.only(top:15.0,left: 10.0,right: 10.0),
                child:SizedBox(
                  height: 40.0,
                child: TextField(
                  controller: emailController,
                  keyboardType: TextInputType.emailAddress,
                  decoration: InputDecoration(
                      labelText: 'Email (Optional)',
                      labelStyle:
                      TextStyle(fontFamily: 'Exo2', color: Colors.grey),
                      border: OutlineInputBorder(
                        borderRadius: BorderRadius.circular(5.0)
                      ),
                      focusedBorder: OutlineInputBorder(
                          borderRadius: BorderRadius.circular(5.0),
                          borderSide: BorderSide(
                              color:
                              Color.fromRGBO(162, 42, 43, 1.0)
                          )

                      )
                  ),
                ),
              )),
              Padding(
                padding: EdgeInsets.only(top:15.0,left: 10.0,right: 10.0,bottom: 30.0),
                child: TextField(
                  maxLines: 3,
                  maxLengthEnforced: true,
                  controller: addressController,
                  keyboardType: TextInputType.emailAddress,
                  decoration: InputDecoration(
                      labelText: 'Address (Optional)',
                      labelStyle:
                      TextStyle(fontFamily: 'Exo2', color: Colors.grey),
                      border: OutlineInputBorder(
                          borderRadius: BorderRadius.circular(5.0)
                      ),
                      focusedBorder: OutlineInputBorder(
                          borderRadius: BorderRadius.circular(5.0),
                          borderSide: BorderSide(
                              color:
                              Color.fromRGBO(162, 42, 43, 1.0)
                          )
                      )
                  ),
                ),
              ),
              Row(
                mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                children: <Widget>[
                  SizedBox(
                    width:130.0,
                  height: 50.0,
                  child:RaisedButton(
                    color: Color.fromRGBO(162, 42, 43, 1.0),
                    shape: RoundedRectangleBorder(
                      borderRadius: BorderRadius.circular(18.0)
                    ),
                    onPressed: (){
                      uploadPic(context);
                      //readUSerData();
                      Navigator.of(context).pop();
                    },
                    elevation: 4.0,
                    splashColor: Colors.blueGrey,
                    child: Text(
                      'Save',
                      style: TextStyle(
                        color:Colors.white,fontSize: 22.0,fontFamily: 'Exo2'
                      ),
                    ),
                  )),
                  SizedBox(
                    width:130.0,
                  height:50.0,
                  child:RaisedButton(
                    color: Color.fromRGBO(162, 42, 43, 1.0),
                    shape: RoundedRectangleBorder(
                        borderRadius: BorderRadius.circular(18.0)
                    ),
                    onPressed: (){
                      Navigator.of(context).pop();
                    },
                    elevation: 4.0,
                    splashColor: Colors.blueGrey,
                    child: Text(
                      'Cancel',
                      style: TextStyle(
                          color:Colors.white,fontSize: 22.0,fontFamily: 'Exo2'
                      ),
                    ),
                  ))
                ],
              )
            ],
          ),
        ),
      ),
    );
  }
}

Answer 1

You can create a constructor for your second page that takes in the data you need. You then pass that data into the page when you call the Navigator eg

class UserProfile extends StatefulWidget {

  final String username;

  const UserProfile({Key key, this.username}) : super(key: key);

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

Then in your first page when navigating you call:

Navigator.push(context, MaterialPageRoute(builder: 
    (context) => UserProfile(username: userName)))