Question 247458 in Firebase Question posted in
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How to read the event when a Cloud Function is triggered in a Firebase Extension?

I’m trying to follow the docs regarding get started with a Firebase Extension using Firebase Functions Firestore 2nd-gen. Inside my extension.yaml file I have created a resource:

resources:
  - name: onDocCreate
    type: firebaseextensions.v1beta.function
    description: >-
      A function that fires when a new document is created.
    properties:
      eventTrigger: 
        eventType: providers/cloud.firestore/eventTypes/document.create
        resource: projects/${PROJECT_ID}/databases/(default)/documents/docs/{docId}
      runtime: "nodejs18"

Inside my index.js file, I have added these lines of code:

const {
  onDocumentCreated,
} = require("firebase-functions/v2/firestore");

exports.onDocCreate = onDocumentCreated("docs/{docId}", (event) => {
  const data = event.data;
  if (!data) {
    console.log("No data associated with the event");
    return;
  }
  const docId = event.params.docId;
  console.log("docId: " + docId);
});

When I a dd a new document in the "docs" collection I always get:

No data associated with the event

As per my understanding, the onDocumentCreated fires but with no data. If I comment the first 5 lines and I try to log the docId, I always get:

docId: undefined

How solve this issue?

resources:
  - name: onDocCreate
    type: firebaseextensions.v1beta.function
    description: >-
      A function that fires when a new document is created.
    properties:
      eventTrigger: 
        eventType: google.cloud.firestore.document.v1.created
        resource: projects/${PROJECT_ID}/databases/(default)/documents/docs/{docId}
      runtime: "nodejs18"
      platform: "gcfv2"
Tags:

2

Answers


  1. 0

    The reason you get a "No data associated with the event" message is because the extension is defined with a 1st gen compatible trigger, but the code is only listening for a 2nd gen compatible trigger. Because of the differences in the request bodies, the data is not properly parsed for use in your function.

    This line in your extension.yaml file targets a firestore.onCreate Cloud Function 1st gen:

    eventType: providers/cloud.firestore/eventTypes/document.create

    To target an onDocumentCreated Cloud Function for 2nd gen, you would have to update it to use the correct eventType:

    eventType: google.cloud.firestore.document.v1.created

    Now that you have the correct eventType there are a couple of other properties to be updated according to the extension.yaml reference – the value for type and properties.buildConfig.runtime (instead of using properties.runtime):

    resources:
  - name: onDocCreate
    type: firebaseextensions.v1beta.v2function
    description: >-
      A function that fires when a new document is created.
    properties:
      buildConfig:
        runtime: nodejs18
      eventTrigger:
        eventType: google.cloud.firestore.document.v1.created
        resource: projects/${PROJECT_ID}/databases/(default)/documents/docs/{docId}

    You should then be able to deploy this resource with your extension.

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  2. 0

    firebaser here

    Firestore triggers for v2 functions are currently not documented, but should work.

    As suggested in some other responses, the resource type for v2 functions must be firebaseextensions.v1beta.v2function. You can use some other documented v2 triggert as an example here:
    https://firebase.google.com/docs/extensions/publishers/functions#crashlytics

    Also, the resource filter format is different for v2 functions. It relies on Eventarc event filtering, so you need to use event filter syntax. Some available Firestore filters are documented here: https://cloud.google.com/functions/docs/calling/cloud-firestore#deploy_the_hello_firestore_function

    Also, event filter syntax for v2 functions is documented here: https://cloud.google.com/functions/docs/reference/rpc/google.cloud.functions.v2#eventfilter

    So, perhaps try something like this:

    resources:
  - name: ondoccreate
    type: firebaseextensions.v1beta.v2function
    description: >-
      A function that fires when a new document is created.
    properties:
      buildConfig:
        runtime: nodejs18
      eventTrigger:
        eventType: google.cloud.firestore.document.v1.created
        triggerRegion: nam5
        eventFilters:
          - attribute: database
            value: (default)
          - attribute: document
            value: docs/{docId}
            operator: match-path-pattern

    (also note the function naming requirements for v2 functions, upper case letters are not supported)

    EDIT: added the required triggerRegion. You might want to make it a parameter for users to control, at least until the extensions platform adds a way automatically infer it.

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