CODEWITHSUNDEEP
node.jsfirebasefirebase-realtime-databasegoogle-cloud-functions
DevMike
DevMike

Reputation: 1821

How do i reference Firebase's realtime database from within a cloud function?

In a Firebase Cloud function i am attempting to retrieve data from my Realtime Database and write an update to it as well. This is where i am having trouble.

The function:

const functions = require('firebase-functions');
const admin = require('firebase-admin');

admin.initializeApp();
...

api.post('/messages/add', (request: any, response: any) => {

  const dbRef:any = functions.database.ref(`count/${request.body.chatRoomId}`);

  dbRef.once('value').then((snapshot:any) => {
      let messageCount:number = (snapshot.val() && snapshot.val().messages) || 0;
      messageCount = Number(messageCount + 1);
      dbRef.update({
        messages: messageCount,
        updated: admin.database().database.ServerValue.TIMESTAMP
      });
  });

});

When i call this function from the client, in the firebase cloud console logs, i am seeing the following error:

TypeError: dbRef.once is not a function

I have tried referencing the database in each of the following ways, all of which fail:

functions.database.ref(`count/${request.body.chatRoomId}`).once('value').then((snapshot)) =>

functions.database.ref(`count/${request.body.chatRoomId}`).once('value', (snapshot) =>

admin.database().ref(`count/${request.body.chatRoomId}`).once('value').then((snapshot)) =>

admin.database().ref(`count/${request.body.chatRoomId}`).once('value', (snapshot) =>

When attempting the reference using the Admin SDK via admin.database() i get a different error:

TypeError: Cannot read property 'ServerValue' of undefined
    at dbRef.once.then

Lastly, i can confirm that the value for ${request.body.chatRoomId} is resolving correctly, i had tested this by printing its value to the console.

The answer here shows how to reference the realtime database from the 'event' response within a realtime database listener like onWrite() for example, however my function is not triggered by realtime database changes, but rather is an endpoint reachable from the client.

UPDATE

The answer proposed by Doug Stevenson below is correct but there was also an additional error due to attempting to write a timestamp incorrectly to a field that i had initially excluded which was causing my function to fail despite having tried his solution, thus I have updated the code to reflect this.

First, the answer is to reference the Realtime Database with admin.database()

Second, even though i had tried this, i was still seeing an error, but the error was due to attempting to set a timestamp incorrectly. Thanks to Frank van Puffelen for pointing this out.

This: admin.database().database.ServerValue.TIMESTAMP

Needs to be: admin.database.ServerValue.TIMESTAMP

And with that it works.

Upvotes: 0

Views: 1038

Answers (1)

Doug Stevenson
Doug Stevenson

Reputation: 317948

You're making the mistake of trying to use the functions SDK to query the database. This is not actually creating a database reference:

functions.database.ref(`count/${request.body.chatRoomId}`);

The functions SDK is just used for declaring and configuring Cloud Functions.

What you should be doing instead is using the Admin SDK to create a reference, then query it:

admin.database().ref(...).once(...)

You also need to initialize the Admin SDK exactly once before you use it:

admin.initializeApp();

Upvotes: 2

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