Develop Reference

Flutter StreamBuilder widget Error : type ' () => Map<String, dynamic >' is not a subtype of type 'DocumentSnapshot<Object?>' in type cast

Error : type ' () => Map<String, dynamic >' is not a subtype of type 'DocumentSnapshot<Object?>' in type cast.
Below is the code sample of my chat screen which is one of the major component of my chat appllication where I wanted to build a stream of messages using the firebase but this gives an error app works completely fine till this screen but after this screen it throws an error please help me resolve this issue , I am using Streambuilder widget , please look into it
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:firebase_core/firebase_core.dart';
import 'package:flutter/material.dart';
import 'package:lets_chat/constant.dart';
import 'package:firebase_auth/firebase_auth.dart';
//final _firestore = FirebaseFirestore.instance;
//FirebaseUser = loggedInUser;
late User loggedInUser;
class ChatScreen extends StatefulWidget {
static const String id3 = 'chat_screen';
#override
_ChatScreenState createState() => _ChatScreenState();
}
class _ChatScreenState extends State<ChatScreen> {
final messageTextController = TextEditingController();
final _fireStore = FirebaseFirestore.instance;
final _auth = FirebaseAuth.instance;
late String messageText;
#override
void initState() {
// TODO: implement initState
super.initState();
getCurrentUser();
}
void getCurrentUser() async {
try {
final user = await _auth.currentUser;
if (user != null) {
loggedInUser = user;
}
} catch (e) {
print(e);
}
}
void messagesStream() async {
await for (var snapshot in _fireStore.collection('messages').snapshots()) {
for (var messages in snapshot.docs) {
print(messages.data);
}
}
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
leading: null,
actions: <Widget>[
IconButton(
icon: Icon(Icons.close),
onPressed: () {
//Implement logout functionality
}),
],
title: Text('⚡️Chat'),
backgroundColor: Colors.lightBlueAccent,
),
body: SafeArea(
child: Column(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
crossAxisAlignment: CrossAxisAlignment.stretch,
children: <Widget>[
StreamBuilder<QuerySnapshot>(
stream: _fireStore.collection('messages').snapshots(),
builder: (context, snapshot) {
if (!snapshot.hasData) {
return Center(
child: CircularProgressIndicator(),
);
}
final messages = snapshot.data?.docs;
List<MessageBubble> messageBubbles = [];
for (var message in messages!) {
final messageText =
(message.data as DocumentSnapshot)['text'];
final messageSender =
(message.data as DocumentSnapshot)['sender'];
final currentUser = loggedInUser.email;
final messageBubble = MessageBubble(
sender: messageSender,
text: messageText,
loggedUser: currentUser == messageSender,
);
messageBubbles.add(messageBubble);
}
return Expanded(
child: ListView(
children: messageBubbles,
),
);
},
),
Container(
decoration: kMessageContainerDecoration,
child: Row(
crossAxisAlignment: CrossAxisAlignment.center,
children: <Widget>[
Expanded(
child: TextField(
controller: messageTextController,
onChanged: (value) {
messageText = value;
},
decoration: kMessageTextFieldDecoration,
),
),
TextButton(
onPressed: () {
_fireStore.collection('messages').add({
'text': messageText,
'sender': loggedInUser.email,
});
},
child: Text(
'Send',
style: kSendButtonTextStyle,
),
),
],
),
),
],
),
),
);
}
}
class MessageBubble extends StatelessWidget {
MessageBubble(
{required this.sender, required this.text, required this.loggedUser});
final String sender;
final String text;
final bool loggedUser;
#override
Widget build(BuildContext context) {
return Padding(
padding: EdgeInsets.all(10.0),
child: Column(
crossAxisAlignment: CrossAxisAlignment.end,
children: [
Text(
'sender',
style: TextStyle(
color: Colors.pink,
),
),
Material(
elevation: 5.0,
borderRadius: BorderRadius.only(
topLeft: Radius.circular(20.0),
bottomLeft: Radius.circular(20.0),
bottomRight: Radius.circular(20.0)),
color: loggedUser
? Colors.pinkAccent.shade200
: Colors.blueAccent.shade200,
child: Padding(
padding:
EdgeInsets.symmetric(vertical: 10.0, horizontal: 10.0),
child: Text('$text from $sender'))),
],
),
);
}
}

Issue with your code is that you're trying to do message.data as DocumentSnapshot which is trying to cast () => Map<String, dynamic> (returned by .data) to a DocumentSnapshot, which is incorrect.
message is a QuerySnapshot and you need to use data() method to access the fields.
final messages = snapshot.data?.docs;
List<MessageBubble> messageBubbles = [];
for (var message in messages!) {
final messageText = message.data()['text'];
final messageSender = message.data()['sender'];
// ...
}

Chat app showing messages randomly when user sends a message and messages are not in proper order

I have made a basic chat app using firebase after completing my tutorial. but the app does not always show messages in order. Also, my messages are supposed to start from the bottom but they don't always do.
I have implemented firebase and firestore packages like this as I was getting error messages while mentioning the version.
dependencies:
flutter:
sdk: flutter
cupertino_icons: ^0.1.2
animated_text_kit: ^4.1.1
firebase_core:
firebase_auth:
cloud_firestore:
modal_progress_hud: ^0.1.3
In the tutorial, it's shown that you have to add .reversed after documents like the code below.
final messages = snapshot.data.documents.reversed;
But when I tried to do the same the document property doesn't exist instead we have to use .docs
and I then tried to add .reversed after docs but still, the problem persists and messages come randomly. I also tried deleting the collection from firebase as shown in the tutorial.
below is the code to fetch the stream of messages.
class streamOfMessages extends StatelessWidget {
const streamOfMessages({#required this.users,});
final CollectionReference users;
#override
Widget build(BuildContext context) {
return StreamBuilder(
stream: users.snapshots(),
// ignore: missing_return
builder: (BuildContext context, AsyncSnapshot<QuerySnapshot> snapshot){
if(!snapshot.hasData){
return Center(
child: CircularProgressIndicator(
backgroundColor: Colors.blueAccent,
),
);
}
final messages = snapshot.data.docs.reversed;
List<messageBubble> messageWidgets = [];
for(var message in messages){
final messageText = message.data()['text'];
final messageSender = message.data()['sender'];
final messageWidget = messageBubble(
message: messageText,
sender: messageSender,
isMe: userEmail == messageSender,
);
messageWidgets.add(messageWidget);
}
return Expanded(
child: ListView(
children: messageWidgets,
reverse: true,
),
);
});
}
}
I also tried to add a timestamp but I think I am doing something wrong. any help is much appreciated Thank you.
I have written a code in the ChatScreen dart file where I have defined everything like displaying messages and Text editing stuff.
Everything else is working fine just messages are being shown in the wrong order.
below is the whole code of the chat screen
any help is much appreciated.
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:flash_chat/constants.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
final _auth = FirebaseAuth.instance;
final _firestore = FirebaseFirestore.instance;
String userEmail;
class ChatScreen extends StatefulWidget {
static String id = 'chat_screen';
#override
_ChatScreenState createState() => _ChatScreenState();
}
class _ChatScreenState extends State<ChatScreen> {
final messageController = TextEditingController();
CollectionReference users = FirebaseFirestore.instance.collection('messages');
String messageText;
#override
void initState() {
super.initState();
loggeduser();
}
void loggeduser(){
try{
final user = _auth.currentUser;
if(user != null){
print(user.email);
userEmail = user.email;
}
}catch(e){
print(e);
}
}
void getMessages() async {
await for (var snapshot in _firestore.collection('messages').snapshots()){
for (var message in snapshot.docs){
print(message.data());
}
}
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
leading: null,
actions: <Widget>[
IconButton(
icon: Icon(Icons.logout),
onPressed: () {
_auth.signOut();
Navigator.pop(context);
}),
],
title: Text('⚡️Chat'),
centerTitle: true,
backgroundColor: Colors.lightBlueAccent,
),
body: SafeArea(
child: Column(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
crossAxisAlignment: CrossAxisAlignment.stretch,
children: <Widget>[
streamOfMessages(users: users),
Container(
decoration: kMessageContainerDecoration,
child: Row(
crossAxisAlignment: CrossAxisAlignment.center,
children: <Widget>[
Expanded(
child: TextField(
controller: messageController,
onChanged: (value) {
messageText = value;
},
decoration: kMessageTextFieldDecoration,
),
),
FlatButton(
onPressed: () {
messageController.clear();
_firestore.collection('messages').add({
'text' : messageText,
'sender' : userEmail,
});
},
child: Text(
'Send',
style: kSendButtonTextStyle,
),
),
],
),
),
],
),
),
);
}
}
// ignore: camel_case_types
class streamOfMessages extends StatelessWidget {
const streamOfMessages({#required this.users,});
final CollectionReference users;
#override
Widget build(BuildContext context) {
return StreamBuilder(
stream: users.snapshots(),
// ignore: missing_return
builder: (BuildContext context, AsyncSnapshot<QuerySnapshot> snapshot){
if(!snapshot.hasData){
return Center(
child: CircularProgressIndicator(
backgroundColor: Colors.blueAccent,
),
);
}
final messages = snapshot.data.docs.reversed;
List<messageBubble> messageWidgets = [];
for(var message in messages){
final messageText = message.data()['text'];
final messageSender = message.data()['sender'];
final messageWidget = messageBubble(
message: messageText,
sender: messageSender,
isMe: userEmail == messageSender,
);
messageWidgets.add(messageWidget);
}
return Expanded(
child: ListView(
children: messageWidgets,
reverse: true,
),
);
});
}
}
// ignore: camel_case_types
class messageBubble extends StatelessWidget {
final String message;
final String sender;
final bool isMe;
messageBubble({this.message, this.sender, this.isMe, this.time});
#override
Widget build(BuildContext context) {
return Padding(
padding: EdgeInsets.all(10.0),
child: Column(
crossAxisAlignment: isMe ? CrossAxisAlignment.end : CrossAxisAlignment.start,
children: [
Text('$sender',
style: TextStyle(fontSize:10.0, color: Colors.black54),
),
Material(
borderRadius: isMe ? BorderRadius.only(topLeft: Radius.circular(30.0),bottomLeft: Radius.circular(30.0),bottomRight: Radius.circular(30.0)) :
BorderRadius.only(bottomLeft: Radius.circular(30.0),bottomRight: Radius.circular(30.0),topRight: Radius.circular(30.0)),
elevation: 5.0,
color: isMe ? Colors.lightBlueAccent : Colors.white,
child: Padding(
padding: EdgeInsets.symmetric(vertical: 10.0,horizontal: 10.0),
child: Text(message,
style: TextStyle(fontSize: 16.0,
color: isMe ? Colors.white : Colors.black54),),
)
),
],
),
);
}
}

So I found the answer you have to add a timestamp to the code and sort method to the list and problem solved.
Below is the code where changes are done.
"....." = means same code no changes needed.
............
Expanded(
child: TextField(
controller: messageController,
onChanged: (value) {
messageText = value;
},
decoration: kMessageTextFieldDecoration,
),
),
FlatButton(
onPressed: () {
messageController.clear();
_firestore.collection('messages').add({
'text' : messageText,
'sender' : userEmail,
'time' : DateTime.now(), --------------> Change here
});
print(DateTime.now());
},
child: Text(
'Send',
style: kSendButtonTextStyle,
),..............
another Change below
.............
child: CircularProgressIndicator(
backgroundColor: Colors.blueAccent,
),
);
}
final messages = snapshot.data.docs.reversed;
List<messageBubble> messageWidgets = [];
for(var message in messages){
final messageText = message.data()['text'];
final messageSender = message.data()['sender'];
final messageTime = message.data()['time']; ---------> added
final messageWidget = messageBubble(
message: messageText,
sender: messageSender,
isMe: userEmail == messageSender,
time: messageTime, -----------------------------------> Add this
);
messageWidgets.add(messageWidget); -----------------------------> Add bot
messageWidgets.sort((a , b ) => b.time.compareTo(a.time)); ------> h lines
}
return Expanded(
child: ListView(
children: messageWidgets,
reverse: true,
),
);
Below another change
.............
class messageBubble extends StatelessWidget {
final String message;
final String sender;
final bool isMe;
final Timestamp time; ------------------> This is added
messageBubble({this.message, this.sender, this.isMe, this.time}); ----> add this.time
#override
Widget build(BuildContext context) {

How to take the datas from firebase in order?

I am currently developing chat app, the problem is I can not take the datas from firebase, on the chat screen nothing shown as a chat, To sort my datas on firebase to take them to my chat screen like a real chat app, I used orderBy('createAt', descending: true).snapshots() property, It sort my datas on firebase according time, but before I used this parameter I could see the messages but now I can, Thanks for your answers, Have a nice day..
import 'package:flutter/material.dart';
import'package:cloud_firestore/cloud_firestore.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:naber/constants.dart';
final _firestore=FirebaseFirestore.instance;
User loggedInUser;
class ChatScreen extends StatefulWidget {
static String id="chat_screen";
#override
_ChatScreenState createState() => _ChatScreenState();
}
class _ChatScreenState extends State<ChatScreen> {
final messageTextController = TextEditingController();
final _auth = FirebaseAuth.instance;
String messageText;
void initState(){
super.initState();
getCurrentUser();
}
void getCurrentUser()async{
try{
final currentUser = await _auth.currentUser;
if(currentUser!=null){
loggedInUser=currentUser;
}
}
catch(e){
print(e);
}
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
leading: null,
actions: <Widget>[
IconButton(
icon: Icon(Icons.close),
onPressed: () {
_auth.signOut();
Navigator.pop(context);
}),
],
title: Text('Chat'),
backgroundColor: Colors.lightBlueAccent,
),
body: SafeArea(
child: Column(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
crossAxisAlignment: CrossAxisAlignment.stretch,
children: <Widget>[
MessagesStream(),
Container(
decoration: kMessageContainerDecoration,
child: Row(
crossAxisAlignment: CrossAxisAlignment.center,
children: <Widget>[
Expanded(
child: TextField(
controller: messageTextController,
onChanged: (value) {
messageText = value;
},
decoration: kMessageTextFieldDecoration,
),
),
FlatButton(
onPressed: () {
messageTextController.clear();
_firestore.collection('messages').add({
'text': messageText,
'sender': loggedInUser.email,
'createdAt': FieldValue.serverTimestamp(),
});
},
child: Text(
'Send',
style: kSendButtonTextStyle,
),
),
],
),
),
],
),
),
);
}
}
class MessagesStream extends StatelessWidget {
#override
Widget build(BuildContext context) {
return StreamBuilder<QuerySnapshot>(
stream: _firestore.collection('messages').
orderBy('createAt', descending: true).snapshots(),
builder: (context, snapshot) {
if (!snapshot.hasData) {
return Center(
child: CircularProgressIndicator(
backgroundColor: Colors.lightBlueAccent,
),
);
}
final messages = snapshot.data.docs.reversed;
List<MessageBubble> messageBubbles = [];
for (var message in messages) {
final messageText = message.data()['text'];
final messageSender = message.data()['sender'];
final currentUser = loggedInUser.email;
final messageBubble = MessageBubble(
sender: messageSender,
text: messageText,
isMe: currentUser == messageSender,
);
messageBubbles.add(messageBubble);
}
return Expanded(
child: ListView(
reverse: true,
padding: EdgeInsets.symmetric(horizontal: 10.0, vertical: 20.0),
children: messageBubbles,
),
);
},
);
}
}
class MessageBubble extends StatelessWidget {
MessageBubble({this.sender, this.text, this.isMe});
final String sender;
final String text;
final bool isMe;
#override
Widget build(BuildContext context) {
return Padding(
padding: EdgeInsets.all(10.0),
child: Column(
crossAxisAlignment:
isMe ? CrossAxisAlignment.end : CrossAxisAlignment.start,
children: <Widget>[
Text(
sender,
style: TextStyle(
fontSize: 12.0,
color: Colors.black54,
),
),
Material(
borderRadius: isMe
? BorderRadius.only(
topLeft: Radius.circular(30.0),
bottomLeft: Radius.circular(30.0),
bottomRight: Radius.circular(30.0))
: BorderRadius.only(
bottomLeft: Radius.circular(30.0),
bottomRight: Radius.circular(30.0),
topRight: Radius.circular(30.0),
),
elevation: 5.0,
color: isMe ? Colors.lightBlueAccent : Colors.white,
child: Padding(
padding: EdgeInsets.symmetric(vertical: 10.0, horizontal: 20.0),
child: Text(
text,
style: TextStyle(
color: isMe ? Colors.white : Colors.black54,
fontSize: 15.0,
),
),
),
),
],
),
);
}
}
[![Here is my database screenshot][1]][1]

FLUTTER - Can someone help me get this post button to execute?

I hope you all are doing well today. I have another flutter issue that I have been stuck on for the past few days now. I'm attempting to upload this data to my firestore instance, but my post button never seems to be triggering. I have attempted to print a statement from the method that it evokes, but I can't seem to get that to work either. I'm attempting to create a social media app, and any and all help would be appreciated.
My main goal is to get the post button to execute in upload.dart.
I have also included home.dart since the two classes are connected in terms of performance.
upload.dart
import 'dart:io';
import 'package:cached_network_image/cached_network_image.dart';
import 'package:firebase_storage/firebase_storage.dart';
import 'package:flutter/material.dart';
import 'package:flutter_svg/flutter_svg.dart';
import 'package:fluttermedia/models/user.dart';
import 'package:fluttermedia/pages/home.dart';
import 'package:fluttermedia/widgets/progress.dart';
import 'package:image_picker/image_picker.dart';
import 'package:path_provider/path_provider.dart';
import 'package:image/image.dart' as Im;
import 'package:uuid/uuid.dart';
class Upload extends StatefulWidget {
final User currentUser;
Upload({this.currentUser});
#override
_UploadState createState() => _UploadState();
}
class _UploadState extends State<Upload> {
TextEditingController locationController = TextEditingController();
TextEditingController captionController = TextEditingController();
File file;
bool isUploading = false;
String postId = Uuid().v4();
handleChooseFromGallery() async{
Navigator.pop(context);
File file = await ImagePicker.pickImage(source: ImageSource.gallery);
setState(() {
this.file = file;
});
}
handleTakePhoto() async {
Navigator.pop(context);
File file = await ImagePicker.pickImage(source: ImageSource.camera,maxHeight: 675,maxWidth: 960);
setState(() {
this.file = file;
});
}
selectImage(parentContext){
return showDialog(
context: parentContext,
builder: (context) {
return SimpleDialog(
title: Text("Create Post"),
children: <Widget>[
SimpleDialogOption(
child: Text("Photo With Camera"),
onPressed: handleTakePhoto,
),
SimpleDialogOption(
child: Text("Image from Gallery"),
onPressed: handleChooseFromGallery,
),
SimpleDialogOption(
child: Text("Cancel"),
onPressed: () => Navigator.pop(context),
),
],
);
}
);
}
Container buildSplashScreen(){
return Container(
color: Theme.of(context).accentColor.withOpacity(0.6),
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
SvgPicture.asset('assets/images/upload.svg',height: 260.0,),
Padding(
padding: EdgeInsets.only(top:20.0),
child: RaisedButton(
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(8.0),
),
child: Text(
"Upload Image",
style: TextStyle(
color: Colors.white,
fontSize: 22.0,
),
),
color: Colors.deepOrange,
onPressed: () => selectImage(context),
),
)
],
),
);
}
clearImage(){
setState(() {
file = null;
});
}
//This compresses images for firebase
compressImage() async{
final tempDir = await getTemporaryDirectory();
final path = tempDir.path;
Im.Image imageFile = Im.decodeImage(file.readAsBytesSync());
final compressedImageFile = File('$path/img_$postId.jpg')..writeAsBytesSync(Im.encodeJpg(imageFile,quality: 85));
setState(() {
file = compressedImageFile;
});
}
Future<String> uploadImage(imageFile) async{
StorageUploadTask uploadTask = storageRef.child("post_$postId.jpg").putFile(imageFile);
StorageTaskSnapshot storageSnap = await uploadTask.onComplete;
String downloadUrl = await storageSnap.ref.getDownloadURL();
return downloadUrl;
}
//upload new info to firestore that creates a new collection
createPostInFirestore({String mediaUrl, String location, String description}){
postsRef.document(widget.currentUser.id)
.collection("userPosts")
.document(postId)
.setData({
"postId": postId,
"ownerId": widget.currentUser.id,
"username": widget.currentUser.username,
"mediaUrl": mediaUrl,
"description": description,
"location": location,
"timestamp": timeStamp,
"likes":{}
});
}
//Getting the info from the caption, location and pic
handleSubmit() async{
setState(() {
isUploading = true;
});
await compressImage();
String mediaUrl = await uploadImage(file);
createPostInFirestore(
mediaUrl: mediaUrl,
location: locationController.text,
description: captionController.text,
);
captionController.clear();
locationController.clear();
setState(() {
file = null;
isUploading = false;
});
}
Scaffold buildUploadForm(){
return Scaffold(
appBar: AppBar(
backgroundColor: Colors.white70,
leading: IconButton(
icon: Icon(Icons.arrow_back,color: Colors.black,),
onPressed: clearImage,
),
title: Text(
"Caption Post",
style: TextStyle(color: Colors.black),
),
actions: <Widget>[
FlatButton(
onPressed: () => isUploading ? null : () => handleSubmit(),
child: Text(
"Post",
style: TextStyle(
color: Colors.blueAccent,
fontWeight: FontWeight.bold,
fontSize: 20.0,
),
),
)
],
),
body: ListView(
children: <Widget>[
isUploading ? linearProgress(context):Text(""),
Container(
height: 220.0,
width: MediaQuery.of(context).size.width*0.8,
child: Center(
child: AspectRatio(
aspectRatio: 16/9,
child: Container(
decoration: BoxDecoration(
image: DecorationImage(
fit: BoxFit.cover,
image: FileImage(file),
)
),
),
),
),
),
Padding(
padding: EdgeInsets.only(top:10),
),
ListTile(
leading: CircleAvatar(
backgroundImage: CachedNetworkImageProvider(widget.currentUser.photoUrl),
),
title: Container(
width: 250.0,
child: TextField(
controller: captionController,
decoration: InputDecoration(
hintText: "Write a Caption...",
border: InputBorder.none,
),
),
),
),
Divider(),
ListTile(
leading: Icon(Icons.pin_drop,color: Colors.orange,size: 35.0),
title: Container(
width: 250.0,
child: TextField(
controller: locationController,
decoration: InputDecoration(
hintText: "Where was this photo taken",
border: InputBorder.none,
),
),
),
),
Container(
width: 200.0,
height: 100.0,
alignment: Alignment.center,
child: RaisedButton.icon(
label: Text(
"Use Current Location",
style: TextStyle(color: Colors.white),
),
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(30.0),
),
color: Colors.blue,
onPressed: () => print("Get user location"),
icon: Icon(
Icons.my_location,
color: Colors.white,
),
),
)
],
),
);
}
#override
Widget build(BuildContext context) {
return file == null ? buildSplashScreen() : buildUploadForm();
}
}
home.dart
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:firebase_storage/firebase_storage.dart';
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:fluttermedia/models/user.dart';
import 'package:fluttermedia/pages/activity_feed.dart';
import 'package:fluttermedia/pages/create_account.dart';
import 'package:fluttermedia/pages/profile.dart';
import 'package:fluttermedia/pages/search.dart';
import 'package:fluttermedia/pages/upload.dart';
import 'package:google_sign_in/google_sign_in.dart';
final GoogleSignIn googleSignIn = GoogleSignIn();
final StorageReference storageRef = FirebaseStorage.instance.ref();
final usersRef = Firestore.instance.collection('users');
final postsRef = Firestore.instance.collection('posts');
final DateTime timeStamp = DateTime.now();
User currentUser;
class Home extends StatefulWidget {
#override
_HomeState createState() => _HomeState();
}
class _HomeState extends State<Home> {
bool isAuth = false;
PageController pageController;
int pageIndex = 0;
#override
void initState() {
super.initState();
pageController = PageController();
// Detects if user signs in
googleSignIn.onCurrentUserChanged.listen((account) {
handleSignIn(account);
}, onError: (err){
print('Error sigining in: $err');
});
//Reauthenticate user when app is opened
googleSignIn.signInSilently(suppressErrors: false)
.then((account) =>
handleSignIn(account)).catchError((err){
print('Error signing in on retry: $err');
});
}
#override
Widget build(BuildContext context) {
return isAuth ? buildAuthScreen() : buildUnAuthScreen();
}
#override
void dispose(){
pageController.dispose();
super.dispose();
}
//Helper Functions
//The sign in section of the code
handleSignIn(GoogleSignInAccount account){
if(account != null){
createUserInFirestore();
setState(() {
isAuth = true;
});
}else{
setState(() {
isAuth = false;
});
}
}
login(){
googleSignIn.signIn();
}
logout(){
googleSignIn.signOut();
}
onPageChanged(int pageIndex){
setState(() {
this.pageIndex = pageIndex;
});
}
createUserInFirestore() async{
// 1) Check if user exists in users collection in database (According to id)
final GoogleSignInAccount user = googleSignIn.currentUser;
DocumentSnapshot doc = await usersRef.document(user.id).get();
if(!doc.exists){
// 2) If the user doesn't exist, take them to create account page
final username = await Navigator.push(context, MaterialPageRoute(builder: (context) => CreateAccount()));
// 3) get username from create account, use it to make new user document in users collection
usersRef.document(user.id).setData({
"id":user.id,
"username":username,
"photoUrl": user.photoUrl,
"email":user.email,
"displayName": user.displayName,
"bio":"",
"timeStamp": timeStamp,
});
doc = await usersRef.document(user.id).get();
}
currentUser = User.fromDocument(doc);
//print(currentUser);
//print(currentUser.username);
}
onTap(int pageIndex){
//This what you would use to animate in between the different screens
pageController.animateToPage(
pageIndex,
duration: Duration(milliseconds: 300),
curve: Curves.easeInOut
);
}
//UI Code
Widget buildAuthScreen() {
return Scaffold(
body: PageView(
children: <Widget>[
//Timeline(),
RaisedButton(
child: Text('Logout'),
onPressed: logout,
),
ActivityFeed(),
Upload(currentUser: currentUser),
Search(),
Profile(),
],
controller: pageController,
onPageChanged: onPageChanged,
physics: NeverScrollableScrollPhysics(),
),
bottomNavigationBar: CupertinoTabBar(
currentIndex: pageIndex,
onTap: onTap,
activeColor: Theme.of(context).primaryColor,
items: [
BottomNavigationBarItem(icon: Icon(Icons.whatshot),),
BottomNavigationBarItem(icon: Icon(Icons.notifications_active),),
BottomNavigationBarItem(icon: Icon(Icons.photo_camera, size: 34.0,),),
BottomNavigationBarItem(icon: Icon(Icons.search),),
BottomNavigationBarItem(icon: Icon(Icons.account_circle),),
],
),
);
/*return RaisedButton(
child: Text('Logout'),
onPressed: logout,
);*/
}
Scaffold buildUnAuthScreen() {
return Scaffold(
body: Container(
width: MediaQuery.of(context).size.width,
height: MediaQuery.of(context).size.height,
decoration: BoxDecoration(
gradient: LinearGradient(
begin: Alignment.topRight,
end: Alignment.bottomLeft,
colors: [
Theme.of(context).primaryColor,
Theme.of(context).accentColor,
]
)
),
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
crossAxisAlignment: CrossAxisAlignment.center,
children: <Widget>[
Text('FlutterMedia',
style: TextStyle(
fontFamily: "Signatra",
fontSize: 90.0,
color: Colors.white
),
),
GestureDetector(
onTap:() => login(),
child: Container(
width: 260,
height: 60,
decoration: BoxDecoration(
image: DecorationImage(
image: AssetImage('assets/images/google_signin_button.png'),
fit: BoxFit.cover,
),
),
),
)
],
),
),
);
}
}

onPressed: () => isUploading ? null : () => handleSubmit(),
Well, there's your problem. You meant to have a tertiary condition that makes onPressed call handleSubmit when isUploading is false. Instead, you have made onPressed into a function that returns a function.
To hopefully make that more clear, let's blow this function up into proper non-lambda functions and if/else blocks:
onPressed: () {
if (isUploading) {
return null;
} else {
return () {
handleUpload();
}
}
}
So consider what happens when the button is pressed. It calls the outer function, which checks isUploading. If true, the function returns null, and if false, it returns another function that, if called, calls handleUpload. So how this plays out is that onPressed will never be null (it just returns null sometimes) and handleUpload never gets called (since the inner function that is returned is never then called itself).
Remove the outer lambda and it will work:
onPressed: isUploading ? null : () => handleSubmit(),

Cloud Firebase list reversal

i am creating a simple chat app using Cloud Firebase, but sometime when i am adding text it is getting added in random position, although I have used reversed to reverse the list, can anyone have some idea to solve it...
hers's my code...
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:flash_chat/constants.dart';
import 'package:flutter/material.dart';
final _firestore = FirebaseFirestore.instance;
User loggedinUser;
class ChatScreen extends StatefulWidget {
static const String route = '/chat';
#override
_ChatScreenState createState() => _ChatScreenState();
}
class _ChatScreenState extends State<ChatScreen> {
final _auth = FirebaseAuth.instance;
final messageTextController =
TextEditingController(); // to remove the sent message from the textbox
String messageText;
void getCurrentUser() async {
/*
* Default is null; as user logs in it contains some value
* */
try {
final user = await _auth.currentUser;
if (user != null) {
loggedinUser = user;
loggedinUser.email;
//print('res************************************: $recentLoggedInUser');
}
} catch (e) {}
}
// void getMessages() async {
// final messages = await _firestore.collection('messages').get();
// for (var message in messages.docs) {
// print(message.data());
// }
// }
// void messagesStream() async {
// await for (var snapshot in _firestore.collection('messages').snapshots()) {
// for (var message in snapshot.docs) {
// print(message.data());
// }
// }
// }
#override
void initState() {
// TODO: implement initState
super.initState();
getCurrentUser();
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
leading: null,
actions: <Widget>[
IconButton(
icon: Icon(Icons.close),
onPressed: () {
// messagesStream();
_auth.signOut();
Navigator.pop(context);
}),
],
title: Text('⚡️Chat'),
backgroundColor: Colors.lightBlueAccent,
),
body: SafeArea(
child: Column(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
crossAxisAlignment: CrossAxisAlignment.stretch,
children: <Widget>[
messageStreams(), // Just get the stream here to populate
Container(
decoration: kMessageContainerDecoration,
child: Row(
crossAxisAlignment: CrossAxisAlignment.center,
children: <Widget>[
Expanded(
child: TextField(
controller:
messageTextController, // this controller handels the text after being sent
onChanged: (value) {
messageText = value;
},
decoration: kMessageTextFieldDecoration,
),
),
FlatButton(
onPressed: () {
/*
* add method receives a map that accepts <String, dynamic> format;
* field name should be same as defined into firebase portal
* */
// use the controller to clear the text box as soon as it is sent
messageTextController.clear();
_firestore.collection('messages').add({
'text': messageText,
'sender': loggedinUser.email,
});
},
child: Text(
'Send',
style: kSendButtonTextStyle,
),
),
],
),
),
],
),
),
);
}
}
class messageStreams extends StatelessWidget {
#override
Widget build(BuildContext context) {
return StreamBuilder<QuerySnapshot>(
stream: _firestore.collection('messages').snapshots(),
builder: (context, snapshot) {
if (!snapshot.hasData) {
return Center(
child: CircularProgressIndicator(
backgroundColor: Colors.lightBlueAccent,
),
);
}
final messages = snapshot.data.docs.reversed;
// .reversed; // reversed make a list in reversed order, so newest will appear at lowest
List<messageBubble> messagewidgets = [];
for (var m in messages) {
final messageText = m.get('text');
final senderText = m.get('sender'); // get sender email from DB
var recentLogger = loggedinUser.email;
CrossAxisAlignment c = recentLogger == senderText
? CrossAxisAlignment.end
: CrossAxisAlignment.start;
final messageWidgit = messageBubble(
sender: senderText,
text: messageText,
crossAxisAlignments: c,
);
messagewidgets.add(messageWidgit);
}
/*
* As we have Container, we will use expanded, this way it will take only the part that is necessary
* */
return Expanded(
child: ListView(
reverse: true,
padding: EdgeInsets.symmetric(
horizontal: 10.0,
vertical: 20.0,
),
children: messagewidgets,
),
);
},
);
}
}
class messageBubble extends StatelessWidget {
final sender;
final text;
CrossAxisAlignment crossAxisAlignments;
messageBubble({this.sender, this.text, this.crossAxisAlignments});
#override
Widget build(BuildContext context) {
BorderRadius br;
Color clr;
if (crossAxisAlignments == CrossAxisAlignment.start) {
br = BorderRadius.only(
topRight: Radius.circular(30.0),
bottomLeft: Radius.circular(30.0),
bottomRight: Radius.circular(30.0),
);
clr = Colors.lightBlueAccent;
} else if (crossAxisAlignments == CrossAxisAlignment.end) {
br = BorderRadius.only(
topLeft: Radius.circular(30.0),
bottomLeft: Radius.circular(30.0),
bottomRight: Radius.circular(30.0),
);
clr = Colors.blueAccent;
}
return Padding(
padding: EdgeInsets.all(10.0),
child: Column(
crossAxisAlignment: crossAxisAlignments,
children: <Widget>[
Text(
sender,
style: TextStyle(
fontSize: 12.0,
color: Colors.black54,
),
),
BuildChatList(br, clr),
],
),
);
}
Material BuildChatList(BorderRadius br, Color clr) {
return Material(
borderRadius: br,
elevation: 5.0,
color: clr,
child: Padding(
padding: const EdgeInsets.symmetric(vertical: 10.0, horizontal: 20.0),
child: Text(
'$text',
style: TextStyle(
color: Colors.white,
fontSize: 15.0,
),
),
),
);
}
}
//BorderRadius.only(
//topLeft: Radius.circular(30.0),
//bottomLeft: Radius.circular(30.0),
//bottomRight: Radius.circular(30.0),
//)
Please follow the image:
here i have got what's up on the top, rather I did it after 2 messages.
Can anyone help me to solve the issue, thanks in advance.

You can add orderBy() to descend sorting the message. for example firestore.collection('messages').orderBy("created_at", descending: true).snapshots().