@firebase/firestore-compat

Data Retrieval

This feature allows you to retrieve data from a Firestore database. The code sample demonstrates how to fetch a document from the 'users' collection using a specific user ID.

const db = firebase.firestore();
const docRef = db.collection('users').doc('user_id');
docRef.get().then((doc) => {
  if (doc.exists) {
    console.log('Document data:', doc.data());
  } else {
    console.log('No such document!');
  }
}).catch((error) => {
  console.log('Error getting document:', error);
});

Data Modification

This feature covers adding or updating data in Firestore. The code sample shows how to set data for a document in the 'users' collection, effectively creating or updating a document.

const db = firebase.firestore();
db.collection('users').doc('user_id').set({
  firstName: 'John',
  lastName: 'Doe'
}).then(() => {
  console.log('Document successfully written!');
}).catch((error) => {
  console.error('Error writing document: ', error);
});

Real-time Updates

This feature enables listening to real-time updates of a document in Firestore. The code sample illustrates how to subscribe to changes in a document, receiving updates automatically whenever the document data changes.

const db = firebase.firestore();
const docRef = db.collection('users').doc('user_id');
docRef.onSnapshot((doc) => {
  if (doc.exists) {
    console.log('Current data: ', doc.data());
  } else {
    console.log('No such document!');
  }
});