Firestore Security Rules - how to prevent modification of a certain field

Question

Let\'s assume we have a Firestore collection called todos, where each todo will look something like this:

{
    name: \"Buy milk\",
    complete         


        

Answer 1

At "Writing conditions for Cloud Firestore Security Rules" section "Data validation" example #2

service cloud.firestore {
  match /databases/{database}/documents {
    // Make sure all cities have a positive population and
    // the name is not changed
    match /cities/{city} {
      allow update: if request.resource.data.population > 0
                    && request.resource.data.name == resource.data.name;
    }
  }
}

So request.resource.data.user == resource.data.user should work for you? CMIIW

Ref: https://firebase.google.com/docs/firestore/security/rules-conditions#data_validation