CODEWITHSUNDEEP
javascriptfirebasefirebase-realtime-databasegoogle-cloud-functions
haki
haki

Reputation: 9759

Updating a ref in a change Firebase trigger in Google Cloud Functions

I have a messages entry that looks like this:

firbaseapp
 messages
   -KiG85eYMH7jfKph4bl3
      created: 1492788734743
      title: "title"
      message: "message"

I want to send a notification when new entries are added to this list so I added this cloud function: 

exports.sendMessageNotification = functions.database.ref('/messages/').onWrite(event => {

    event.data.forEach(message => {

        if (message.val().notificationSent) {
            return;
        }

        admin.messaging().sendToTopic(...)
        .then(res => {
            return db.ref('/messages').child(message.key).update({
                notificationSent: (new Date()).getTime(),
            });
        })
    });
});

Problem is message.key is messages-KiG85eYMH7jfKph4bl3 so when I try to save it, it creates a new entry instead of updating the existing one:

firbaseapp
 messages
   -KiG85eYMH7jfKph4bl3
      created: 1492788734743
      title: "title"
      message: "message"
   -messages-KiG85eYMH7jfKph4bl3
      notificationSent: 123434554534

What I wanted is for notificationSent to be set on the existing entry.

I also tried using message.ref but I get the same result.

So what is the best way to update a list item in firebase in a cloud function?

Upvotes: 2

Views: 1374

Answers (1)

Bob Snyder
Bob Snyder

Reputation: 38289

I think this accomplishes what you want to do and also answers your questions in the comments:

exports.sendMessageNotification = functions.database.ref('/messages/{messageId}')
  .onWrite(event => {
    const messageId = event.params.messageId;
    console.log('messageId=', messageId);

    if (event.data.current.child('notificationSent').val()) {
        console.log('already sent');
        return;
    }

    const ref = event.data.ref; // OR event.data.adminRef

    admin.messaging().sendToTopic(...)
        .then(res => {
            return ref.update({
                // Caution: this update will cause onWrite() to fire again
                notificationSent: (new Date()).getTime(),
            });
        })
});

Upvotes: 3

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