Firebase Database Get All Value In Order Cloud Functions - node.js

Question

I develop for Firebase Cloud Functions. I have a Firebase Realtime Database like this:
----- myData
-------eqewrwrepere (this one is a device token)
---------Lta+sde-fer (this one is a firebase id)
firstvalue : "a"
secondvalue : "b"
----------Qrgd+ad-qdda (this one is second firebase id)
firstvalue : "c"
secondvalue : "d"
-------eqwerSAsdqe (this one is another device token)
---------Lta+sde-fer (this one is a firebase id)
firstvalue : "x"
secondvalue : "y"
----------Qrgd+ad-qdda (this one is second firebase id)
firstvalue : "z"
secondvalue : "t"
I fetch these data by this code. With this code i fetch all data and put them an array. And when fetching done, i loop this array for finding items. I am an iOS developer, so i am a newbie for NodeJS. Here is what i want to do:
Get firstvalue for each database data.
Make a api request with firstvalue of each database data.
Api returns an image.
Write image temp directory.
Process this image for visionApi.
Extract text.
Update database.
Send notification for deviceToken
Now i am able to retrieve database items in my array. When i make a request in for loop, request called async. So for loop continues, but request response or writing file and vision processing executed only once.
In for loop, get databasearray[0], make request, write file, process it with vision api, update database and go for next databasearray[1] item.
I read about Promises on different pages. But i did not understand.
Thank you.
'use strict';
const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp(functions.config().firebase);
var request = require('request');
var fs = require('fs');
//var fs = require("fs");
// Get a reference to the Cloud Vision API component
const Vision = require('#google-cloud/vision');
const vision = new Vision.ImageAnnotatorClient();
// Imports the Google Cloud client library
//const {Storage} = require('#google-cloud/storage');
var fs = require("fs");
var os = require("os");
var databaseArray = [];
exports.hourly_job = functions.pubsub
.topic('hourly-job')
.onPublish((event) => {
console.log("Hourly Job");
var db = admin.database();
var ref = db.ref("myData")
ref.once("value").then(function(allData) {
allData.forEach(function(deviceToken) {
deviceToken.forEach(function(firebaseIDs) {
var deviceTokenVar = deviceToken.key;
var firebaseIDVar = firebaseIDs.key;
var firstvalue = firebaseIDs.child("firstvalue").val();
var secondvalue = firebaseIDs.child("secondvalue").val();
var items = [deviceTokenVar, firebaseIDVar, firstvalue, secondvalue];
databaseArray.push([...items]);
});
});
return databaseArray;
}).then(function(databasem) {
var i;
for (i = 0; i < databaseArray.length; i++) {
var databaseArrayDeviceToken = databaseArray[i][0];
console.log("DeviceToken: " + databaseArrayDeviceToken);
var databaseArrayFirebaseID = databaseArray[i][1];
console.log("FirebaseID: " + databaseArrayFirebaseID);
var databaseArrayfirstvalue = databaseArray[i][2];
console.log("firstval: " + databaseArrayfirstvalue);
var databaseArraysecondval = databaseArray[i][3];
console.log("Second: " + databaseArraysecondval);
var url = "http://api.blabla" + databaseArrayfirstvalue;
/////////////here make a request, pause loop, process returned image, but how //////////////////////
request.get({
url: url,
encoding: 'binary'
}, function(error, httpResponse, body) {
if (!error && httpResponse.statusCode == 200) {
fs.writeFileSync('/tmp/processed.jpg', body, 'binary')
console.log("file written");
})
}
});
return true;
});

Answer 1

I found solution with Mocas helps. Here is the solution. I use async/await functions in code. Now for loop waits for the function response. But now I have different problems. I think main async function hangs because of awaits. And then next hourly trigger, it runs again. So console log shows 15-16-17 or more ‘i’ values in for loop. I have 4 element in database array but console log shows more than this every hour. And it increases every time. So I guess that I should cancel this await functions after a timeout. But I don’t know how. Here is code:
use strict';
const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp(functions.config().firebase);
var request = require('request-promise').defaults({ encoding: null });
var fs = require('fs');
// Get a reference to the Cloud Vision API component
const Vision = require('#google-cloud/vision');
const vision = new Vision.ImageAnnotatorClient();
var os = require("os");
var databaseArray = [];
var uniqueFilename = require('unique-filename')
exports.hourly_job = functions.pubsub
.topic('hourly-job')
.onPublish((event) => {
console.log("Hourly Job");
var db = admin.database();
var ref = db.ref("myData")
ref.once("value").then(function(allData) {
allData.forEach(function(deviceToken) {
deviceToken.forEach(function(firebaseIDs) {
var deviceTokenVar = deviceToken.key;
var firebaseIDVar = firebaseIDs.key;
var firstvalue = firebaseIDs.child("firstvalue").val();
var secondvalue = firebaseIDs.child("secondvalue").val();
var items = [deviceTokenVar, firebaseIDVar, firstvalue, secondvalue];
databaseArray.push([...items]);
//console.log(databaseArray);
//return true;
});
//return true;
});
return databaseArray;
}).then(function (databasem) {
main().catch(console.error);
});
return true;
});
const main = async () => {
var i;
for (i = 0; i < databaseArray.length; i++) {
console.log("Database Arrays " + i + ". elements: ");
var databaseArrayDeviceToken = databaseArray[i][0];
console.log("DeviceToken: " + databaseArrayDeviceToken);
var databaseArrayFirebaseID = databaseArray[i][1];
console.log("FirebaseID: " + databaseArrayFirebaseID);
var databaseArrayfirst = databaseArray[i][2];
console.log("first: " + databaseArrayfirst);
var databaseArraysecond = databaseArray[i][3];
console.log("second: " + databaseArraysecond);
if (databaseArrayfirst != "") {
var apiUrl = "http://api.blabla;
try {
const apiBody = await request.get(apiUrl);
///////////////////////////vison start//////////////////////
const visionResponseBody = await vision.documentTextDetection(apiBody)
var visionResponse = visionResponseBody[0].textAnnotations[0].description;
console.log("Vision response text " + visionResponse );
...some logic here about response...
/////////////////////////////////////////////////
var getdatabasevar = await admin.database().ref("myData/" + databaseArrayDeviceToken + "/" + databaseArrayFirebaseID);
await getdatabasevar.update({
"firstvalue": visionResponse
});
/////////////////////////////////////////////////
var getanotgerdatabasevar = await admin.database().ref("myData/" + databaseArrayDeviceToken + "/" + databaseArrayFirebaseID + "/" + "secondvalue");
await getanotgerdatabasevar.once("value")
.then(function(var) {
..some logic..
//send notification
});
} catch (error) {
console.error(error);
}
///////////////////////////vison end//////////////////////
}
};
return true;
};