Update a Firestore document containing an array field.

Update a Firestore document containing an array field.

Code sample

Java

DocumentReference washingtonRef = db.collection("cities").document("DC");

// Atomically add a new region to the "regions" array field.
ApiFuture<WriteResult> arrayUnion = washingtonRef.update("regions",
    FieldValue.arrayUnion("greater_virginia"));
System.out.println("Update time : " + arrayUnion.get());

// Atomically remove a region from the "regions" array field.
ApiFuture<WriteResult> arrayRm = washingtonRef.update("regions",
    FieldValue.arrayRemove("east_coast"));
System.out.println("Update time : " + arrayRm.get());

Node.js

const admin = require('firebase-admin');
// ...
const washingtonRef = db.collection('cities').doc('DC');

// Atomically add a new region to the "regions" array field.
const unionRes = await washingtonRef.update({
  regions: admin.firestore.FieldValue.arrayUnion('greater_virginia')
});
// Atomically remove a region from the "regions" array field.
const removeRes = await washingtonRef.update({
  regions: admin.firestore.FieldValue.arrayRemove('east_coast')
});

Python

city_ref = db.collection(u'cities').document(u'DC')

# Atomically add a new region to the 'regions' array field.
city_ref.update({u'regions': firestore.ArrayUnion([u'greater_virginia'])})

# // Atomically remove a region from the 'regions' array field.
city_ref.update({u'regions': firestore.ArrayRemove([u'east_coast'])})