add / update array Firestore

Question

I'm working with Firestore. The following code updates the matrix with a single element, that is, each time a user executes that function, said field is updated:

updateFavoritos(key) {
    const user = firebase.auth().currentUser;
    this.afs.doc('eventos/' + key).update({
      favoritos: [ user.uid ],
    });
  }

This looks like this:

But how can I do to add instead of updating that matrix, is to say something like this:

Possible duplicate of [How to update an "array of objects" with Firestore?](https://stackoverflow.com/questions/46757614/how-to-update-an-array-of-objects-with-firestore) — Guruprasad J Rao, May 13 '19 at 15:44

score 0 · Answer 1 · answered Apr 18 '20 at 18:31

Firestore have methods to handle arrays. Link to the docs

var washingtonRef = db.collection("cities").doc("DC");

// Atomically add a new region to the "regions" array field.
washingtonRef.update({
    regions: firebase.firestore.FieldValue.arrayUnion("greater_virginia")
});

// Atomically remove a region from the "regions" array field.
washingtonRef.update({
    regions: firebase.firestore.FieldValue.arrayRemove("east_coast")
});

add / update array Firestore

1 Answers1