Firebase 消息：向所有使用云的应用程序用户发送数据消息 function

Question

How could I approach messaging all users of an app?
With the web GUI it is possible to send a notification message to all users of an app, so I assume doing the same with a function and a data message (or at least with a notification message) is possible with a function too - but I couldn't find a way to do that.

My Attempt

I tried subscribing all devices to a topic, by calling:

FirebaseMessaging.getInstance().subscribeToTopic("all");

In the onCreate event of my FirebaseMessagingService , then sending a message with a cloud function:

exports.sendMessage = functions.database.ref("/messages/{meta}")
    .onCreate((snapshot, context) => {
        const message = snapshot._data;
        console.log("msg", message["title"]);
        // logs the correct data, therefore the event triggers
        const payload = {
            data: {
                title: message["title"]
                /* blah blah */
            },

            topic: "all"
        }

        admin.database().ref("/messages/" + context.params.meta).remove()
        return admin.messaging().send(payload)
    })

But onMessageReceived doesn't trigger (unlike when I send a notification message using the GUI).
Is this approach viable in any way? What am I missing?

Answer 1

I believe the only part you will need to change is the end. You won't need this part here admin.database().ref("/messages/" + context.params.meta).remove() .

For the messaging, your code needs to look something like the below sample:

// Send a message to devices subscribed to the provided topic.
admin.messaging().send(payload)
  .then((response) => {
    // Response is a message ID string.
    console.log('Successfully sent message:', response);
  })
  .catch((error) => {
    console.log('Error sending message:', error);
  });

You need to user a catch to manage the error - this way you will be able to visualize as well, what might be causing your issue. You can find more information in this documentation here: Send messages to topics .

Besides that, I found this nice repository - that you can access here - with some examples and more code samples, on how to use Cloud Functions with FCM.

Let me know if the information helped you!