FieldValue.increment(1) doenst work as expected-CodePudding

In my code I want to increment the usage by the value 1. I have the usage in firebase and I use it in a chart. I use this function to increment by the value 1:

addActivity(
    int day,
  ) async {
    final documentSnapshot = await FirebaseFirestore.instance
        .collection('users')
        .doc(FirebaseAuth.instance.currentUser!.uid.toString())
        .collection('activity')
        .doc('${globals.year}')
        .collection('week${globals.week}')
        .doc(day.toString())
        .set({'usage': FieldValue.increment(1)});
  }

The problem is that whatever I do the usage value is always set to the value that is in the braces (now 1). I tested this with multiple values and it doesnt seem to work. When I change the initial value to 2 the value after tapping the button isnt 3 but 1...

I'm open and thankful to/for all suggestions :)

CodePudding user response：

That way it's written now using set(), your code always going to overwrite the contents of the document. If you want to update a document, you should use update() instead to update an existing document, or set() with the merge option (SetOptions(merge: true)).

    .set({'usage': FieldValue.increment(1)}, SetOptions(merge: true));

CodePudding user response：

To achieve the desired effect you should use update method. set overrides data so it actually sets 1 each time for you. So, just refactor to this

.update({'usage': FieldValue.increment(1)});