firebase.database.ref 不是 function React Native / Expo

Question

I am pretty new to expo and firebase, and I have this error that I have no idea what the issue is. I am trying to fetch photos from firebase database. I know for sure the issue is not with firebase config because I can upload photos into firebase storage.

I suspect the issue is with exporting and importing firebase.

This is the error message I am getting:

[TypeError: _firebase.db.ref is not a function. (In '_firebase.db.ref('users/photos')', '_firebase.db.ref' is undefined)]

Note: I am using firebase v9

App.js file:

import { db } from './firebase';

export default function App() {

  async function loadPhotos() {
    try {
      db.ref('users/photos')
        .then(url => {
          console.log('URL: ', url);
        })
        .catch(e => console.log(e));
      console.log('Got here');
    } catch (error) {
      console.log('error', error);
    }
  }
 ...............
}

firebase.js file:

import firebase from 'firebase/compat/app';
import { getDatabase } from 'firebase/database';

const firebaseConfig = {
  apiKey: '......',
  authDomain: '.....',
  projectId: '....',
  storageBucket: '....',
  messagingSenderId: '....',
  appId: '.....',
  measurementId: '....',
};

if (!firebase.apps.length) {
  firebase.initializeApp(firebaseConfig);
}
export const db = getDatabase();

Answer 1

In v9 and later of the Firebase SDK, most functionality that was a method on the objects in the past, is now available as a top-level function.

So instead of db.ref('users/photos') , you need to do ref(db, 'users/photos') .

You're also missing a get call, which is how you actually retrieve the data from the reference:

get(ref(db, 'users/photos'))
  .then(url => {
    console.log('URL: ', url);
  })
  .catch(e => console.log(e));

This is all pretty well documented in the Firebase documentation on reading data , so I recommend keeping that handy. Alternatively you can use the compat paths in v9, to make the older syntax work as shown in the upgrade guide /