DB.collection is not a function in firebase? - node.js

Question

I am trying to connect to firebase realtime database (not firestore) but I get the error that db.collection is not a function. Other answers in StackOverflow are mentioned with respect to Firestore. Thanks for your help.
const admin = require('firebase-admin');
// Firebase configuration - this should not be public.
// Please use your own config if you intend to use this code.
var firebaseConfig = {
apiKey: "xxxxxxxxxxxxxxxxxx",
authDomain: "xxxxxxxxxxxxxxxxxx",
databaseURL: "xxxxxxxxxxxxxxxxxx",
projectId: "xxxxxxxxxxxxxxxxxx",
storageBucket: "xxxxxxxxxxxxxxxxxx",
messagingSenderId: "xxxxxxxxxxxxxxxxxx",
}
// Initialize Firebase
admin.initializeApp(firebaseConfig)
const db = admin.database();
console.log("Database setup");
(async () => {
try {
let query = db.collection('users');
console.log("Doing database query now");
await query.get().then(querySnapshot => {
console.log(querySnapshot);
});
} catch (error) {
console.log(error);
}
})();

Answer 1

const db = admin.database() is an instance of Firebase realtime database and not Firestore. To get an instance of Firestore, use admin.firestore().
const admin = require('firebase-admin');
admin.initializeApp(/* service account */)
const db = admin.firestore();
console.log("Firestore setup");
Admin SDK uses a service account and not the same public credentials. You can refer to the documentation for detailed information. You can get a service account from project settings.
Do note that if you are using Cloud functions then you can leave initializeApp() empty.