Securing user data - Bolt rules

rules.bolt

isUser(uid) = auth != null && auth.uid == uid;

type Post {
  uid: String;
  title: String;
  description: String;
  timestamp: Number;
}

type User {
  uid: String;
  name: String;
  username: String;
}

path /users/$uid is User {
  read() = isUser($uid);
  write() = isUser($uid);
}

path /posts/$postid is Post {
  read() = true;
  write() = isUser(this.uid);
}