Firestore push item to nested Array

Question

I have Database like this

now I need to push items to directors array.

I tried this code

Firestore()
    .collection('notices')
    .doc(item.id)
    .set({readBy: {directors: [user.id]}}, {merge: true});

but it replace the existing items in directors array.

How to push items to directors array without replacing existing items ?

Does this answer your question? How to update an "array of objects" with Firestore? — Tahir Yasin
– Tahir Yasin, Commented Jul 20, 2020 at 7:20
No that is not. That is Array of objects. my one is object of arrays — Priyashan Jayasankha
– Priyashan Jayasankha, Commented Jul 20, 2020 at 7:21

l1b3rty · Accepted Answer · 2020-07-20 08:28:16Z

1

You need to use the arrayUnion function for this:

Firestore()
.collection('notices')
.doc(item.id)
.set({readBy: {directors: FieldValue.arrayUnion([user.id])}}, {merge: true});

answered Jul 20, 2020 at 8:28

l1b3rty

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