Firebase Flutter arrayUnion 什么都不做

Question

I'm trying to add a specific id to a array of children, but everytime I run my code it simply does nothing and I'm not sure why.

 Future addChild() async {
    await FirebaseFirestore.instance.collection('users').doc(id).update({
      'children': FieldValue.arrayUnion([cid])
    });
  }

This is the current Firestore Database I have:

Answer 1

you need to add one key which only store list of ids i think the mistak your code is you add or update directly in json so you jave to try like this way and for example hear i am add "cidList" key in "children". in my project, I m use arrayUnion in "usersLikesMe" keys in add to users id.

await FirebaseFirestore.instance.collection('users').doc(id).set({
  'children.cidList': FieldValue.arrayUnion([cid])
},SetOptions(merge: true));