Error while retrieving data from FireBase into flutter project - firebase

Question

I am working with Flutter sdk version 2.12.0.I am creating a chat app which can be used to chat with other users. The chat history will be stored in fireBase . I am trying to retrieve the data of what I chatted and display it on the screen using Stream Builder widget.
As i keep chatting the data should get automatically added.
I am getting the following error:
Closure call with mismatched arguments: function '[]'
Receiver: Closure: () => Map<String, dynamic> from Function 'data':.
Tried calling: []("text")
Found: []() => Map<String, dynamic>
I am not able to figure out which function has mis Matched arguments. Can you please me with it. Here is my code:
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:flashchat1/constants.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
class ChatScreen extends StatefulWidget {
static String id='Chat_Screen';
#override
_ChatScreenState createState() => _ChatScreenState();
}
class _ChatScreenState extends State<ChatScreen> {
final _fireStore = FirebaseFirestore.instance;//an instance of fireBase store that stored data created
final _auth = FirebaseAuth.instance;//instance/object of fireBase auth that authorizes users is created
late User loggedInUser;//LoggedInUser is of type FireBase user(now changed to user)
late String messageText;
#override
void initState()
{
super.initState();
getCurrentUser();//calling the getCurrentUser
}
void getCurrentUser()
async{
try
{
final user= await _auth.currentUser;//get the current user id/name/email.Also currentUser return a future so make it async by adding await and async keywords
if(user!=null)
{
loggedInUser=user ;//LoggedInUser = user contains email of the info
print(loggedInUser.email);
}
}
catch(e)
{
print(e);
}
}// Under collection there is documents.Inside documents there are fields like type ,values etc.These fields contain our information
Future<void> messageStream()//Using a stream it becomes very easy .U just need to click once after you run the app .Then u will be done.
async {//The snapShot here is FireBase's Query SnapShot
await for(var snapshot in _fireStore.collection('messages').snapshots()){//make a variable snapshot to store the entire items of the collection in fireBase (Look at the fireBase console there is a collection called messages).This collection takes the snapshot of all the iteams (not literal snapshot .Think it like a snapShot)
for(var message in snapshot.docs)//make a variable message to access the snapShot.docs .(docs stands for Documentation.Look at the fireBase console)
print(message.data());
}
}
void getMessages()//(The problem with this is that we need to keep clicking on the onPressed button every single time the new message is sent .So it is not convinient
async {
final messages = await _fireStore.collection('messages').get();//to retrieve the data from fire base we are creating a variable message
messages.docs;//retreive the data from document section under the collection in firestore
for(var message in messages.docs)//since it is a messages.docs is a list we need to loop through it
{
print(message.data());//print the data its messge.data()
}
}
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
leading: null,
actions: <Widget>[
IconButton(
icon: Icon(Icons.close),
onPressed: () {
messageStream();
//_auth.signOut();
//Navigator.pop(context);
//Implement logout functionality
}),
],
title: Text('⚡️Chat'),
backgroundColor: Colors.lightBlueAccent,
),
body: SafeArea(
child: Column(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
crossAxisAlignment: CrossAxisAlignment.stretch,
children: <Widget>[
Expanded(
child: StreamBuilder(
stream:_fireStore.collection('messages').snapshots(),
builder: (context, AsyncSnapshot snapshot) {
//This is Flutter's Async snapShot
//if(!snapshot.data)
// {
// return Center(
//child: CircularProgressIndicator(
//backgroundColor:Colors.lightBlueAccent,
//),
//);
//}
if(snapshot.hasData){//flutters async snapshot contains a query snapshot
final messages = snapshot.data.docs;
List<Text> messageWidgets = [];
for(var message in messages)//Loop through the messages
{
final messageText = message.data['text'];//retrieve the data under the text field in message collection
final messageSender = message.data['Sender'];//retrieve the data under the Sender field in message collection
final messageWidget = Text('$messageText from $messageSender');
messageWidgets.add(messageWidget);//add the text to the List messageWidget
}
return Column(//
children: messageWidgets,//if u don't write else with a return it will show an error as null returned and null safety broken
);
}
else{
return Column();
}
},
),
),
Container(
decoration: kMessageContainerDecoration,
child: Row(
crossAxisAlignment: CrossAxisAlignment.center,
children: <Widget>[
Expanded(
child: TextField(
onChanged: (value) {
messageText=value;//Whatever you chat will be stored in the variable String variable messageText
},
decoration: kMessageTextFieldDecoration,
),
),
FlatButton(
onPressed: () {
_fireStore.collection('messages').add({
'text': messageText,//add the messages sent to fireStore under the messages object that we created manually
'Sender': loggedInUser.email,//add the current users email to the sender field
},);
},//goal is to send the data that we type here to the fireStore cloud
child: Text(
'Send',
style: kSendButtonTextStyle,
),
),
],
),
),
],
),
),
);
}
}

Answer 1

Change this:
final messageText = message.data['text'];
final messageSender = message.data['Sender'];
into this:
final messageText = message.data()['text'];
final messageSender = message.data()['Sender'];