Endless loop in firestore - firebase

Question

I'm trying to update my documents in firestore, so when I'm trying to update it keeps updating without stopping. The first time it updates using the data from the signup dart file, then the second time it updates using the data from another dart file.
Here is the code for the signup:
FirebaseAuth auth = FirebaseAuth.instance;
await auth.createUserWithEmailAndPassword(
email: emailController.text, password: passwordController.text)
.then((value) => {
Navigator.pushNamed(context, 'DialogFlow'),
user=auth.currentUser,
user.sendEmailVerification(),
DatabaseService(uid:user.uid).UpdateUserData("", emailController.text, ChatScreenState().mess)
Here is the code for the other dart file:
#override
Widget build(BuildContext context) {
WidgetsBinding.instance.addPostFrameCallback((_) => _scrollToEnd());
FirebaseAuth auth = FirebaseAuth.instance;
user=auth.currentUser;
DatabaseService db = DatabaseService(uid: user.uid);
return StreamBuilder(
stream: FirebaseFirestore.instance.collection("users").doc(user.uid).snapshots(),
builder: (context , snapshot){
print("====================================");
print(snapshot.data);
print("====================================");
if (snapshot.data != null) {
this.userTestMessage = "";
shhh = pressed ? true : false;
flag = true;
print(Retrieved_messages);
if (Retrieved_messages==false) {
this.messsages = snapshot.data['messsages'];
Retrieved_messages=true;
}
db.UpdateUserData(
user.displayName, user.email, this.messsages);
print(mess);
print(Retrieved_messages);
print("==============================");
print(snapshot.data);
print("==============================");
}
if (db.getUserMessages() == null) {
if (user != null) {
db.UpdateUserData(
user.displayName, user.email, this.messsages);
}
}
And the code for the database which sets and updates the documents is:
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:font_awesome_flutter/font_awesome_flutter.dart';
import 'package:satoshi/models/Userdata.dart';
import 'package:satoshi/widgets/dialog_flow.dart';
class DatabaseService {
//collection reference
final String uid;
List messsages=[];
DatabaseService({this.uid, this.messsages});
final CollectionReference userCollection = FirebaseFirestore.instance
.collection('users');
SetUserData(String Username, String Email,
List messsages) async
{ try {
return await FirebaseFirestore.instance.collection("users").doc(uid).set({
'Username': Username,
'Email': Email,
'messsages': messsages,
}
);
}catch(e){
print(e+" this is the error");
}
}
UpdateUserData(String Username, String Email,
List messsages) async
{ try {
return await FirebaseFirestore.instance.collection("users").doc(uid).update({
'Username': Username,
'Email': Email,
'messsages': messsages,
}
);
}catch(e){
print(e+" this is the error");
}
}
Future getUserMessages() async
{
DocumentSnapshot UserDetail = await userCollection.doc(uid).get();
var msg = UserDetail.data()['messsages'];
return await msg;
}
Stream<QuerySnapshot> get users {
return userCollection.snapshots();
}
Userdata userDataFromSnapshot(DocumentSnapshot snapshot) {
return Userdata(uid: uid,
name: snapshot.get('Username'),
email: snapshot.get('Email'),
messsages: snapshot.get('messsages'),
);
}
Stream<Userdata> get userData {
return userCollection.doc(uid).snapshots().asyncMap(userDataFromSnapshot);
}
}
Note: it keeps adding the data in the signup code, then adds the data in the other dart file, which results in an endless loop, also the snapshot isn't updating, it remains the same data as the signup

Answer 1

You are calling the Update function inside the stream builder so what it basically does is once the update function is called firebase gets notified of the document change and rebuilds the widget so again the update function is called and it turns into an infinite loop. what you can do is add any condition such that it won't get called again once the data is updated.
Example
if (<Somecondition>){
db.UpdateUserData(
user.displayName, user.email, this.messsages);
}