FieldValue arrayUnion and Cloud FireStore with Flutter

user_8824640 0
Viewed 16668

I have cloud fire store object like this

"TestCollection" : ["Test1","Test"]

Now I want to update this array with FieldValue.arrayUnion because if element is same then i don't want to do anything but if it is not then I would like to add element

docRef.updateData({"TestCollection":FieldValue.arrayUnion(["test"])})

but this statement gives the error like object can not have nested array

Can anyone please help or provide same kind of example to have look for syntax ?

google-cloud-firestore firebase dart flutter
5 Answers

I have found a solution. Try this:

 Firestore.instance
.collection('YourCollection')
.document('YourDocument')
.updateData({'array':FieldValue.arrayUnion(['data1','data2','data3'])});

If it still doesn't work, try to update your Firebase.

First open a terminal fetched to your flutter project, then:

cd ios
pod update Firebase

This solution is only for mac users.

user_95748480

New FlutterFire Update 2021

With the newest FlutterFire update there where lots of updates at the API but thankfully it hasn't changed that much for this problem. I'm talking about the newest plugins of Firebase for Flutter and specifically every plugin that is compatible with the new firebase_core ^0.7.0. So the code looks similar:

FirebaseFirestore.instance
.collection("YourCollection")
.doc("YourDocument")
.update({
      "anArray": FieldValue.arrayUnion(["data", "to", "append"])
    });
user_115089140

The other way if you have List of objects

Future<void> updateUserNewGroup(List<Group> data , String id) {

    List<Map> list=new List();

    if(data !=null && data.isNotEmpty){
        data.forEach((grp){
            list.add(grp.toJson());
        });
    }


    return ref.document(id).updateData({"groups": FieldValue.arrayUnion(list)}) ;
}
user_43956910

Following up on the existing answers, if the field does not exist you can use a set & merge. This can save you from checking if the field exists or not.

Firestore.instance
  .collection('YourCollection')
  .document('YourDocument')
  .setData({
    'array':FieldValue.arrayUnion(['data1','data2','data3'])
  }, merge: true);
user_101818470

this is the code I used and it worked like a charm!

                _firestore
                .collection('x')
                .document('xxxxxxxxxx')
                .updateData({
              'comments': FieldValue.arrayUnion([
       {'comment': "comment goes here", 'sender': "xxxxxxxx@gmail.com"}
              ])
            });
user_76051520
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