Firestore Security Rules - How can I check that a field is/isn't being modified?

Question

For the life of me, I cannot understand why the following is resulting in a false for allowing writes. Assume my users collection is empty to start

Answer 1

I solved it by using writeFields. Please try this rule.

allow write: if !('role' in request.writeFields);

In my case, I use list to restrict updating fields. It works, too.

allow update: if !(['leader', '_created'] in request.writeFields);