Update realtime database in Firebase

I am creating a API which can update value from realtime database (Firebase). Using ClaudiaJS to create API. Basically, API will update the number of student of a class by year.

What I have done:

Realtime Database (Firebase)

class
 |__2015
 |    |__numberOfStudent: 50
 |__2016
      |__numberOfStudent: 60 

Export to JSON like this:

{
  "class": {
    "2015": {
      "numberOfStudent": 50
    },
    "2016": {
      "numberOfStudent": 60
    }
  }
}

Javascript file (ClaudiaJS):

var ApiBuilder = require('claudia-api-builder');
api = new ApiBuilder();
module.exports = api;

var admin = require("firebase-admin");

var serviceAccount = require("./xxxxxxx-firebase-adminsdk-nxxxxx.json");

admin.initializeApp({
  credential: admin.credential.cert(serviceAccount),
  databaseURL: "https://xxxxxx.firebaseio.com"
});

api.post('/addmore/{year}/{number}', function (request) {
    var database = admin.database().ref('class');

    //Params
    var year = request.pathParams.year;
    var number = request.pathParams.number;

    var ref = year + '/numberOfStudent'; // '2015/numberOfStudent'

    database.update({
        ref : parseInt(number) // "2015/numberOfStudent" : 60
    });

    return 'Update successfully';

});

When I run the api in Postman:

http://xxxxapi.com/addmore/2015/55

What happened: API replied 'Update successfully', but the database didn't get any update. It seems that the code database.update() doesn't work at all.

Any suggestion is very appreciated

The update call happens asynchronously, so currently the return happens before update completes.

update returns a Promise, so try the following:

return database.update({ref : parseInt(number)})
    .then(() => {
        // Each then() should return a value or throw
        return 'Update successful';
    })
    .catch(error => {
        // handle the error however you like
        console.error(error);
    });