How to read data from cloud firestore with firebase function and loop and push it to list

Question

I am trying to read data from firestore collection to get notification token and push it to a list and pass the list to SendtoDevice function to send push notification.

I am facing issue when using foreach function and push the data getting error "for each is not a valid function"


let tokenList = [];

const userNotificationTokenDocs = await db.collection("userToken").doc(userId).get()
.then(querySnapshot => {
querySnapshot.forEach((doc) => {
console.log(doc.data().Tokens);
tokenList.push(doc.data().Tokens);
});
return null;
});

**other option which i tried, with same error.**

userNotificationTokenDocs.forEach(function(docs){
   console.log(docs.data());
   if(docs.data() != null){
    tokenList.push(docs.data().Token);
   }
});

Please help me, I am stuck with this.

You are mixing await and then in the same statement. That doesn't make any sense - just use one or the other. You might want to take a moment to review how Futures work in dart. — Doug Stevenson
– Doug Stevenson, Commented Sep 14, 2022 at 1:30
Thanks for the response. I tried without await still it's not pushing data to the list, and I checked twice querysnapshot it returning data. — fazilSizzlers
– fazilSizzlers, Commented Sep 14, 2022 at 2:21

pmatatias · Accepted Answer · 2022-09-14 02:13:18Z

1

found some BASIC mistake in your coding.

const userNotificationTokenDocs will always null , because you return null. forEach is void function.
Using await and then is unecessery. choose 1.
=> arrow is a shorthand for { return expr; } . if you only have 1 expresion, you can shorthand with arrow. but if you have morethan 1 expression, just use bracket {} . documentation
userNotificationTokenDocs.forEach(function(docs){ this will error since null value cant use forEach.

I think your IDE should give you alert there's an error in your code. but you choose to run it instead fixing the error.

but is ok, keep learning code. :)

answered Sep 14, 2022 at 2:13

pmatatias

4,4783 gold badges18 silver badges47 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

fazilSizzlers Over a year ago

Thanks for the response. I am newbie, i am learning lot of from people like you. thanks. Could you please help me what's wrong with this. var userToken= await db.collection('Users') .doc(userId) .collection('Tokens') .get(); userToken.forEach(function(docs){ if(docs.data() != null){ TokenList.push(docs.data().Token); } });

pmatatias Over a year ago

what current error you get? did you use any additional package? because List on dart doesnt support push() method. if you want to add item to list , use add() method. tokenList.add(docs.data().Token

fazilSizzlers Over a year ago

This is firebase cloud function, i am getting list of usertoken to send push notification, to available users based on token

fazilSizzlers Over a year ago

Error i am getting "TypeError: forEach is not a function"

Collectives™ on Stack Overflow

How to read data from cloud firestore with firebase function and loop and push it to list

1 Answer 1

I think your IDE should give you alert there's an error in your code. but you choose to run it instead fixing the error.

4 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

I think your IDE should give you alert there's an error in your code. but you choose to run it instead fixing the error.

4 Comments

Your Answer

Sign up or log in

Post as a guest

Related