TypeError: Cannot read properties of undefined (reading 'onSnapshot')

Question

Im am trying to collect data from firebase database but get the error 'TypeError: Cannot read properties of undefined (reading 'onSnapshot')'

Feed.js

 const Feed = ({profilePic, message, timestamp, username, image}) => { const [posts, setPosts] =useState([]); //realtime database connection useEffect(() => { db.collection['posts'].onSnapshot(snapshot => ( setPosts(snapshot.docs.map((doc) => ({ id: doc.id, data: doc.data() }))) )); }, []); return (

Firebase.js

 import firebase from 'firebase/compat/app'; import 'firebase/compat/firestore'; //initialize Firebase firebase.initializeApp(firebaseConfig); //database const db = firebase.firestore(); export default db;

Frank van Puffelen · Accepted Answer · 2021-11-13 15:41:48Z

4

The collection is a method, not an array. So:

db.collection('posts').onSnapshot(... // 👆 👆

answered Nov 13, 2021 at 15:41

Frank van Puffelen

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