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Stream returning null even though EVERY print statement is getting printed

I have a Stream which seems to work perfectly fine: Every print statement you see in the stream is getting printed. Also when calling if(snapshot.hasData) it apparently is true. But still, my stream only returns the following: AsyncSnapshot<List<dynamic>>(ConnectionState.done, [], null, null).
What do I need to change in order to be able to access the Data in my retVal variable?
Stream<List>? roomsListStream() {
try {
List<RoomsListModel> retVal = [];
print("userId: $userId");
var rooms = FirebaseFirestore.instance
.collection("rooms")
.where("users", arrayContains: userId)
.orderBy("latestMessageTime", descending: true)
.snapshots();
print("rooms: $rooms");
rooms.forEach((element) {
element.docs.forEach((element) {
print("element: $element");
var room = element.data();
print("room: $room");
var roomId = room["roomId"];
var otherUserId =
room["users"].firstWhere((element) => element != userId);
var lastMessage = room["latestMessage"];
var lastMessageTime = room["latestMessageTime"];
print("otherUserId: $otherUserId");
getOtherUser(otherUserId).then((value) {
print("value: $value");
var avatar = value["photoUrl"];
var name = value["name"];
retVal.add(RoomsListModel(
roomId: roomId,
otherUserId: otherUserId,
avatar: avatar,
name: name,
lastMessage: lastMessage,
lastMessageTime: lastMessageTime));
});
});
});
return Stream.value(retVal);
} catch (e) {
print("Error: $e");
}
}

Try:
var rooms = await FirebaseFirestore.instance
.collection("rooms")
.where("users", arrayContains: userId)
.orderBy("latestMessageTime", descending: true)
.snapshots();

Fetching data from firebase error happen flutter

while building whatsapp clone status uploading to database perfectly done , no issues in that case . But while displaying from DB to screen error found :- I/flutter (11808): RangeError (index): Invalid value: Valid value range is empty: 0
code of getstatus function
Future<List> getStatus(BuildContext context) async {
List statusData = [];
try {
List<Contact> contacts = [];
if (await FlutterContacts.requestPermission()) {
contacts = await FlutterContacts.getContacts(withProperties: true);
}
for (int i = 0; i < contacts.length; i++) {
var statusesSnapshot = await firestore
.collection('status')
.where(
'phoneNumber',
isEqualTo: contacts[i].phones[0].number.replaceAll(
' ',
'',
),
)
.where(
'createdAt',
isGreaterThan: DateTime.now()
.subtract(const Duration(hours: 24))
.microsecondsSinceEpoch,
)
.get();
for (var tempData in statusesSnapshot.docs) {
Status tempStatus = Status.fromMap(tempData.data());
if (tempStatus.whoCanSee.contains(auth.currentUser!.uid)) {
statusData.add(tempStatus);
}
}
}
} catch (e) {
if (kDebugMode) print(e);
showSnackBar(context: context, content: e.toString());
}
return statusData;
}

need some processing to do before cloud function returns a promise. But promise is return before the processing

i have a cloud function where i pass an array of numbers and compare those numbers with collection in the firestore . And if the numbers are present than return an array with those numbers. But before comparing those numbers the function return empty value in the promise.
I've tried using async await but the execution sequence remained same.
//sort contact list
export const addMessage= functions.https.onCall(async (data:any, context) => {
const col=admin.firestore().collection("joshua");
var match:[]
match=data.list
var perm1=new Array()
res11.push("454675556")
console.log("above resolve")
for(let val in match){
var inter=await Promise.all([getValues(col,val)])
console.log("inside resolve"+inter)
}
perm1.push("23432")
console.log("just before resolve")
return new Promise((res,rej)=>{
res(perm1)
})
});
//the async function which is suppose to process on every iteration
function getValues(col1:any,val1:any)
{
return new Promise(async(res,rej)=>{
var query= await col1.where('Listed','array-contains',val1)
var value=await query.get()
res(value)
})
.catch(err=>{
console.log(err)
})
}
i want the sequence to be asynchronous where the return value from getValues is waited upon and inside getValues result of query.get is waited upon.
so that at last return only be sent when all process is finished.

I think this is what you are looking for
export const addMessage= functions.https.onCall(async (data:any, context) => {
const col = admin.firestore().collection("joshua");
var match:[]
match = data.list
var perm1 = []
// res11.push("454675556") // ? undefined
for(let val in match){
var inter = await getValues(col,val)
console.log("inside resolve" + inter)
}
perm1.push("23432") // ??
// console.log("just before resolve")
return Promise.resolve(perm1)
});
const getValues = async (col1:any, val1:any) => {
const query = col1.where('Listed','array-contains', val1)
var value = await query.get().then(getAllDocs)
return value
}
const getAllDocs = function(data: any) {
const temp: Array<any> = []
data.forEach(function (doc: any) {
temp.push(doc.data())
})
return temp
}

Passing custom object through method channel flutter

I am trying to pass a custom object which is of type User from native platform to Flutter. The User class is part of a library and not accessible directly for editing. Here is my android and iOS code implementation for the same. Problem is I am not able to find a solution on how to pass this object through method channels in such a way that I can parse it in the Dart code easily.
Android part:
private fun loginUser(uid: String, apiKey: String, result: MethodChannel.Result) {
MyChat.login(uid, apiKey, object : MyChat.CallbackListener<User>() {
override fun onSuccess(user: User) {
Log.e(TAG, user.toString())
result.success(hashMapOf("RESULT" to true, "AVATAR" to user.avatar,
"CREDITS" to user.credits,
"EMAIL" to user.email,
"LAST_ACTIVE" to user.lastActiveAt,
"NAME" to user.name,
"ROLE" to user.role,
"STATUS" to user.status,
"STATUS_MESSAGE" to user.statusMessage).toString())
}
override fun onError(p0: MyChatException?) {
Log.e(TAG, p0?.message)
result.error("FAILED", "Unable to create login", null)
}
})
}
iOS implementation:
func loginUser(result: #escaping FlutterResult, uid: String, apiKey: String){
MyChat.login(UID: uid, apiKey: apiKey, onSuccess: { (user) in
// Login Successful
let data: [String: Any] = ["RESULT":true,
"AVATAR":user.avatar!,
"CREDITS": user.credits,
"EMAIL": user.email!,
"LAST_ACTIVE":String(user.lastActiveAt),
"NAME":user.name!,
"ROLE":user.role!,
"STATUS":user.status.rawValue,
"STATUS_MESSAGE":user.statusMessage]
let jsonData = try? JSONSerialization.data(withJSONObject: data, options: [.prettyPrinted])
result(String(data: jsonData!, encoding: .ascii))
}) { (error) in
// Login error
result(FlutterError(code: "FAILED", message:"Login failed with exception: " + error.errorDescription, details: nil))
}
}
My dart code:
Future<String> isUserLoggedIn() async {
String status = "";
try {
final String result = await platform
.invokeMethod('loginUser', {"UID": UID, "API_KEY": API_KEY});
print(result); //How to parse?
status = "Hello";
} on PlatformException catch (e) {
print("Exception");
status = e.message;
}
return status;
}

You can pass data in hash map.
In Android:
result.success(hashMapOf(
"CREDITS" to user.credits,
"EMAIL" to user.email,
...
))
In iOS:
let data: [String: Any] = [...]
result(data)
In Flutter:
final result = await platform.invokeMethod<Map<String, dynamic>>('loginUser', ...);
final credits = result['CREDITS'] as String;
final email = result['EMAIL'] as String;
...

you can use invokeMapMethod which is an implementation of invokeMethod that can return typed maps.
like this :
final result = await platform.invokeMapMethod('loginUser', ...);
or you can pass json object as string like that :
in android
platform.success(
"{\"CREDITS\":\"${user.credits}\",\"EMAIL\":\"${user.email}\",\"LAST_ACTIVE\":\"${user.lastActiveAt}\"}"
)
in flutter
var result = await methodChannel.invokeMethod('loginUser' , '');
var json = json.decode(result);
var credit = json['CREDITS'];
var email = json['EMAIL'];
var lastActive = json['LAST_ACTIVE'];

Firebase cloud function gets triggered twice. First time 'error', second time 'ok'

Just trying to impletment Stripe Payment into my Android App.
The trouble i have is that my cloud function is triggered twice when i enter a credit card in my app. the first trigger returns an "error" status and the second trigger returns an "ok" status
Here is the code i use to save the Stripe token to my firebase realtime database:
if (cardToSave != null) {
stripe.createToken(
cardToSave,
object:TokenCallback {
override fun onSuccess(token: Token?) {
val currentUser = FirebaseAuth.getInstance().currentUser?.uid
val database = FirebaseDatabase.getInstance()
val pushId = database.getReference("stripe_customers/$currentUser/sources/").push().key
val ref = database.getReference("stripe_customers/$currentUser/sources/$pushId/token/")
//save the token id from the "token" object we received from Stripe
ref.setValue(token?.id)
.addOnSuccessListener {
Log.d(TAG, "Added Stripe Token to database successfully")
}
.addOnFailureListener {
Log.d(TAG, "Failed to add Token to database")
}
}
...
Here is the cloud function i copied straight from Stripe's example in their github repo:
// Add a payment source (card) for a user by writing a stripe payment source token to Realtime database
exports.addPaymentSource = functions.database
.ref('/stripe_customers/{userId}/sources/{pushId}/token').onWrite((change, context) => {
const source = change.after.val();
if (source === null){
return null;
}
return admin.database().ref(`/stripe_customers/${context.params.userId}/customer_id`)
.once('value').then((snapshot) => {
return snapshot.val();
}).then((customer) => {
return stripe.customers.createSource(customer, {source});
}).then((response) => {
return change.after.ref.parent.set(response);
}, (error) => {
return change.after.ref.parent.child('error').set(userFacingMessage(error));
}).then(() => {
return reportError(error, {user: context.params.userId});
});
});
Any help would be appreciated!
EDIT:
index.js
'use strict';
const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp();
const logging = require('#google-cloud/logging');
//functions.config() is firebase's environment variables
const stripe = require('stripe')(functions.config().stripe.token);
const currency = functions.config().stripe.currency || 'USD';
// [START chargecustomer]
// Charge the Stripe customer whenever an amount is written to the Realtime database
exports.createStripeCharge = functions.database.ref('/stripe_customers/{userId}/charges/{id}')
.onCreate((snap, context) => {
const val = snap.val();
// Look up the Stripe customer id written in createStripeCustomer
return admin.database().ref(`/stripe_customers/${context.params.userId}/customer_id`)
.once('value').then((snapshot) => {
return snapshot.val();
}).then((customer) => {
// Create a charge using the pushId as the idempotency key
// protecting against double charges
const amount = val.amount;
const idempotencyKey = context.params.id;
const charge = {amount, currency, customer};
if (val.source !== null) {
charge.source = val.source;
}
return stripe.charges.create(charge, {idempotency_key: idempotencyKey});
}).then((response) => {
// If the result is successful, write it back to the database
return snap.ref.set(response);
}).catch((error) => {
// We want to capture errors and render them in a user-friendly way, while
// still logging an exception with StackDriver
return snap.ref.child('error').set(userFacingMessage(error));
}).then(() => {
return reportError(error, {user: context.params.userId});
});
});
// [END chargecustomer]]
// When a user is created, register them with Stripe
exports.createStripeCustomer = functions.auth.user().onCreate((user) => {
return stripe.customers.create({
email: user.email,
}).then((customer) => {
return admin.database().ref(`/stripe_customers/${user.uid}/customer_id`).set(customer.id);
});
});
// Add a payment source (card) for a user by writing a stripe payment source token to Realtime database
exports.addPaymentSource = functions.database
.ref('/stripe_customers/{userId}/sources/{pushId}/token').onWrite((change, context) => {
const source = change.after.val();
if (source === null){
return null;
}
return admin.database().ref(`/stripe_customers/${context.params.userId}/customer_id`)
.once('value').then((snapshot) => {
return snapshot.val();
}).then((customer) => {
return stripe.customers.createSource(customer, {source:source});
}).then((response) => {
return change.after.ref.parent.set(response);
}, (error) => {
return change.after.ref.parent.child('error').set(userFacingMessage(error));
}).then(() => {
return reportError(error, {user: context.params.userId});
});
});
// When a user deletes their account, clean up after them
exports.cleanupUser = functions.auth.user().onDelete((user) => {
return admin.database().ref(`/stripe_customers/${user.uid}`).once('value').then(
(snapshot) => {
return snapshot.val();
}).then((customer) => {
return stripe.customers.del(customer.customer_id);
}).then(() => {
return admin.database().ref(`/stripe_customers/${user.uid}`).remove();
});
});
// To keep on top of errors, we should raise a verbose error report with Stackdriver rather
// than simply relying on console.error. This will calculate users affected + send you email
// alerts, if you've opted into receiving them.
// [START reporterror]
function reportError(err, context = {}) {
// This is the name of the StackDriver log stream that will receive the log
// entry. This name can be any valid log stream name, but must contain "err"
// in order for the error to be picked up by StackDriver Error Reporting.
const logName = 'errors';
const log = logging.log(logName);
// https://cloud.google.com/logging/docs/api/ref_v2beta1/rest/v2beta1/MonitoredResource
const metadata = {
resource: {
type: 'cloud_function',
labels: {function_name: process.env.FUNCTION_NAME},
},
};
// https://cloud.google.com/error-reporting/reference/rest/v1beta1/ErrorEvent
const errorEvent = {
message: err.stack,
serviceContext: {
service: process.env.FUNCTION_NAME,
resourceType: 'cloud_function',
},
context: context,
};
// Write the error log entry
return new Promise((resolve, reject) => {
log.write(log.entry(metadata, errorEvent), (error) => {
if (error) {
return reject(error);
}
return resolve();
});
});
}
// [END reporterror]
// Sanitize the error message for the user
function userFacingMessage(error) {
return error.type ? error.message : 'An error occurred, developers have been alerted';
}