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I have a document with an array field in it.

How can I update the array?

In firebase functions, with typescript, I did something like this:

admin.firestore() .collection('friendships') .doc(caller.data["uid"]) .update({ friends: admin.firestore.FieldValue .arrayUnion({ friendDisplayName: snapshot.data["friendDisplayName"], friendUid: snapshot.ref }) })

I cannot find any alternative with Flutter.. how can I do?

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  • this didn't work - Firestore.instance.collection('friendships').document(caller.data["uid"]).updateData({ 'friends':{ 'friendDisplayName': snapshot.data["friendDisplayName"], 'friendUid': snapshot.ref } ? Commented Oct 12, 2018 at 6:25

2 Answers 2

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Something like this

firestore.instance. .collection('friendships') .document(caller.data["uid"]) .updateData({ friends: FieldValue.arrayUnion({ friendDisplayName: snapshot.data["friendDisplayName"], friendUid: snapshot.ref }) });
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what does caller.data retrieve? I'm new to dart and i'm struggling to update array in my Firebase
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The solution I give you is when you use Transactions, but regardless of that, it works the same...

List<dynamic> list = List.from(documentSnapshot.data['uids']); list.add(uid); await documentTransaction.update( postRef, <String, dynamic>{ 'counter': documentSnapshot.data['counter'] + 1, 'uids': list, }, );
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The thing is that some times you don't have the ability to fetch the whole list and then add a new element. It would be nice if you could just add a new element to the existing array without fetching first

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