How to implement a counter function using firebase functions? - node.js

Question

I WANT TO IMPLEMENT A COUNTER FUNCTION USING FIREBASE FUNCTION TO COUNT NO OF TIMES MY APP IS BEING OPENED.
What I want:
Android app opened---> app calling ------>firebase function executed via http trigger------->firebase function increment value stored in firebase database
How to read and update data on firebase realtime database from firebase Functions.
I made an Firebase function which triggers on http triggers.
Code:
const functions = require('firebase-functions');
exports.counterFunction = functions.https.onRequest((request, response) => {
response.send("Hello from Firebase");
******Code to increment value in firebase database*********
});
I have a field in firebase realtime database called count and 0 corresponds to it
count : 0
I want to increment count variable every time the firebase function is executed
IN SHORT I WANT TO IMPLEMENT A COUNTER USING FIREBASE.
I just want to record the number of times my app started . So I am calling the Http Trigger function using http request using 'okhttp' and the function need to increment the count.

Answer 1

The following Firebase function example should help you understand how to write to the realtime database from a function
https://github.com/firebase/functions-samples/tree/3b41b2e04d854a821a0149e1e5b0769bad397d67/quickstarts/uppercase
Have also a look at https://firebase.google.com/docs/functions/get-started

Answer 2

You could try:
const functions = require('firebase-functions');
const admin = require('firebase-admin');
const app = admin.initializeApp();
exports.counterFunction = functions.https.onRequest((request, response) => {
response.send("Hello from Firebase");
return app.database().ref(`/count`).once('value', (snap) => {
const value = snap.val() || 0;
return app.database().ref(`/count`).set(value + 1).then(res => {
return true;
}).catch(err => {
return Promise.reject(err);
});
});
});
This will increment your counter each time your cloud function is executed.