Firebase database query returns null (function)

Question

I'm trying to add some triggered functions to my firebase account but before that i wanted to learn the basics of firebase queries so i wrote a js file and testing it by writing "node index.js" in my command prompt. Learnt a few basic queries from youtube etc and tried to integrate it in my js file however so far no luck at all. All my queries returns null and i didnt understand what part of it i am doing. Could you please have a look.

Thanks in advance.

My database structure

<firebasename>
 users
   edRIPg8BcZU9YPbubp7HtQo7phl1
     sayilar: 2653
     status: "ok"
   hakan
     sayilar: 5000
     status: "waiting"
   mehmet
     sayilar: 7000
     status: "ok"

My database rule:

{
  "rules": {
    "users": {
        ".read": true,
        ".write": true
    }
  }
}

My index.js file:

var firebase = require('firebase');

var config = {
  apiKey: "<my-api-key>",
  authDomain: "<firebasename>.firebaseio.com",
  databaseURL: "https://<firebasename>.firebaseio.com",

};
firebase.initializeApp(config);
ref = firebase.database().ref();
const events = ref.child('users').child('hakan');
const query =events.orderByChild('status').equalTo('ok').limitToFirst(2);

query.on("value", sorunsuz,sorunlu);

function sorunlu(error) {
  console.log("Something went wrong.");
  console.log(error);
}

function sorunsuz(data) {
  
 
    var fruits = data.val();
    console.log(fruits);
}

The command promt shows

null

FIREBASE WARNING: Using an unspecified index. Your data will be downloaded and filtered on the client. Consider adding ".indexOn": "status" at /users/hakan to your security rules for better performance.

Jen Person · Accepted Answer · 2018-01-05 23:15:03Z

3

The issue with the code is here:

ref = firebase.database().ref();
const events = ref.child('users').child('hakan');

events targets this part of the data:

 users
   hakan
     sayilar: 5000
     status: "waiting"

Then you call

const query =events.orderByChild('status').equalTo('ok').limitToFirst(2);

Which queries the children of hakan by their children status, which will return null because neither of the keys under hakan have a child status. It seems like you want to change events to:

const events = ref.child('users')

Then you would order the children of users by their child status.

answered Jan 5, 2018 at 23:15

Jen Person

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1 Comment

Frank van Puffelen Over a year ago

You'll also want to add an index under /users/$userid to get rid of that warning (and prevent the SDK from downloading all user data and filter on the client).

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