CODEWITHSUNDEEP
javascriptfirebase-realtime-databasegoogle-cloud-functions
Matthias
Matthias

Reputation: 23

How to read a value from Realtime Databse using Cloud Functions?

I have a Cloud Functions, which triggers if a certain value in my Realtime Database changes. After that I need to read an other value from the Database.

I searched the web and found one solution. It worked: The function triggered as soon as the value at /ID/temp_id changed, but it took additional 5 seconds to read the value at /ID/I.

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

exports.getID = functions.database.ref("/ID/temp_id").onUpdate((change, context)=>{   //triggers the function when value "temp_id" changes
  const tempID = change.after.val();

  const i_snap = admin.database().ref("/ID/i").once("value", function(snapshot){      //read the value at "/ID/i" from the databse
    const i = snapshot.val();
  })

})

Is there any way to read the value at /ID/I faster?

Upvotes: 2

Views: 561

Answers (2)

Umbro
Umbro

Reputation: 2204

You have to trigger a function through an HTTP request by using functions.https. This allows invoke a synchronous function. Use functions.https to create a function that handles HTTP events. The event handler for an HTTP function listens for the onRequest() event. Used as arguments for onRequest(), the Request object gives you access to the properties of the HTTP request sent by the client, and the Response object gives you a way to send a response back to the client.

exports.date = functions.https.onRequest((req, res) => {
  // ...
});

More details documentation: https://firebase.google.com/docs/functions/http-events

Take a look at the example below:

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

admin.initializeApp(functions.config().firebase);

//Call function via HTTP requests. This allows invoke a synchronous function 
exports.showValue = functions.https.onRequest((req, res) => {
    const params = req.url.split("/");
    const tempId = params[2];
    return admin.database().ref('ID/' + tempId).once('value', (snapshot) => {
        var value = snapshot.val();
        res.send(`
            <!doctype html>
            <html>
                <head>
                    <title>${value.name}</title>
                </head>
                <body>
                    <h1>Title ${value. name}, id ${value.id}</h1>
                </body>
            </html>`
        );
     });
});

Upvotes: 0

Doug Stevenson
Doug Stevenson

Reputation: 317958

In general, you cannot simply speed up a simple database write like that. Be aware that Cloud Functions have an unavoidable cold start time for the first invocation of your function on a new server instance.

I would actually not expect your function to work at all because you're not returning a promise that resolves when all the asynchronous work is complete in your function. You're obliged to do that so that your function terminates normally.

Upvotes: 1

Related Questions