How to send expo push notification to multiple devices?

Question

I'm trying to send Expo push notifications to multiple devices. I'm retrieving the Expo tokens from Firestore. When I enter the tokens manually, it works! It sends the notification to both devices I'm using, but when I retrieve the data from Firestore, it only sends the notification to one device.


async function sendPushNotification(readx) {
  const message = {
    to: readx,
    sound: "default",
    title: "Original Title",
    body: "And here is the body!",
    data: { someData: "goes here" },
  };



  const retrieveNetwork = async () => {
    try {
      //const querySnapshot = await getDocs(collection(db, "cities"));

      const q = query(collection(db, "users"));

 

      const querySnapshot = await getDocs(q);

  
      setRead(querySnapshot.docs.map((doc) => doc.data().expoUser));

      setReadx(JSON.stringify(read));
    
    } catch (e) {
      alert(e);
    }
  };

score 0 · Answer 1 · answered Feb 01 '23 at 10:44

The retrieving of data from the firestore seems to be an issue , as your code is using the Snapshot for querying the data ,it should get the token id for both the devices in the loop and then return to the await sync to call the notification function.As per the Firebase documentation on reading multiple documents, you'll see that it uses the data() function on each DocumentSnapshot to get at the fields of that document.
So try to modify accordingly,like use doc.role and doc.token instead of doc.data().role and doc.data().token. Check this example code below:

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; });

Also you may try adding the below to your code:
userToken.forEach((token) => { console.log(token); tokens.push(token); });
Checkout these following with similar implementation:

HI. Thanks for your answer! Still not working. What else I can do? — Andres Pelaez, Feb 01 '23 at 15:07

score 0 · Answer 2 · answered Feb 01 '23 at 16:07

Just solved. Need to change

 <Button
        title="Press to Send Notification"
        onPress={async () => {
          await sendPushNotification(expoPushToken);
        }}
      />

to

 <Button
        title="Press to Send Notification"
        onPress={async () => {
          await sendPushNotification(readx);
        }}
      />

How to send expo push notification to multiple devices?

2 Answers2