Comparing Cloud Functions for Firebase database triggers onCreate(), onWrite(), onUpdate(), when to use?

Question

It's a simple question, I have seen all these methods addressed in the title in the documentation but all the examples are using onWrite() for triggering database events which then one would have to check to make sure it's not for removing or updating with

exports.makeUppercase = functions.database.ref('/messages/{pushId}/original')
    .onWrite(event => {
...
  // Only edit data when it is first created.
      if (event.data.previous.exists()) {
        return;
      }
      // Exit when the data is deleted.
      if (!event.data.exists()) {
        return;
      }
...
});

The only examples with onCreate() for instance, are related to auth events. Is there a reason or am I just being paranoid? Why not just use onCreate() and not bother the check?

Bob Snyder · Accepted Answer · 2017-08-17 19:41:34Z

4

onCreate(), onUpdate() and onDelete() were added in the Firebase SDK for Cloud Functions (v0.5.9) release on 7 July 2017. This is detailed in the release notes:

An updated beta release of the Firebase SDK for Cloud Functions (v0.5.9) is now available. It includes the ability to listen to granular create, update, and delete database events by using the onCreate(), onUpdate(), and onDelete() methods.

Prior to that release, the only database event handler was onWrite(). The documentation has not yet been updated to include examples of the new handlers.

There is no reason not to take advantage of the convenience of the new handlers.

answered Aug 17, 2017 at 19:41

Bob Snyder

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1 Comment

Manas Over a year ago

thxx @Bob. was wondering how come my push is being triggered when im just updating the post. cuz i was using onWrite() method.

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