CODEWITHSUNDEEP
node.jsfirebasefirebase-realtime-databasegoogle-cloud-functionsfirebase-admin
creativecreatorormaybenot
creativecreatorormaybenot

Reputation: 127024

Firebase Admin Database Snapshot Data After Query?

Setup

Let us imagine that this is my JSON data

values: {
    a: {
        randomValue: "set",
        sorter: 1
    },
    b: {
        randomValue: "hat",
        sorter: 2
    }
}

I can retrieve data from my database with the admin database (from Cloud Functions) like this

admin.database().ref('values/a').once('value').then(snapshot => {
    console.log(snapshot.val().randomValue + ' .. ' + snapshot.val().sorter);
});

Output will be set .. 1.

Problem

As soon as I attach a query to my request it stops working, i.e. it does not work like mentioned in the documentation. There they can clearly access snapshot.val().height with a query.

Although when I do my query like this

admin.database().ref('values').orderByChild('sorter').equalTo(1).once('value').then(snapshot => {
    console.log(snapshot.val());
    console.log(snapshot.val().randomValue + ' .. ' + snapshot.val().sorter);
    console.log(snapshot.child('randomValue').val() + ' .. ' + snapshot.child('sorter').val());
}

The output will suprisingly be the following

a: {
    randomValue: "set",
    sorter: 1
}
undefined .. undefined
null .. null

So snapshot.val() does give me my full data, but not a single way of accessing will give me any data, just undefined or null! Why is this the case?

Upvotes: 0

Views: 1426

Answers (1)

Hiranya Jayathilaka
Hiranya Jayathilaka

Reputation: 7438

I believe you need to access the fields as snapshot.val().a.randomValue in this case. Note that you're running the query against the values node, and not the values/a node. Therefore your result contains the a property.

Update

When you run the query against the values node, and subscribe to the value event (which is what once() method does internally), you get the full value (parent key + child) of the query. To get only the child, you need subscribe to a child event. This is what the samples in the documentation do. For instance:

admin.database().ref('values').orderByChild('sorter').equalTo(1).once('child_added').then(snapshot => { console.log(snapshot.val()); console.log(snapshot.val().randomValue + ' .. ' + snapshot.val().sorter); console.log(snapshot.child('randomValue').val() + ' .. ' + snapshot.child('sorter').val()); });

will yield the output you're trying to get:

{ randomValue: 'set', sorter: 1 } set .. 1 set .. 1

Upvotes: 3

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