Rule Variables are variables which can be accessed by your Rule Expressions. These variables will always exist whenever a Rule Expressions is evaluated, however some variables (such as auth) may be null.
The following variables may be used within expressions:
- auth - Auth data for the client.
- data - A RulesDataSnapshot for the current data in Firebase at the location of this expression.
- newdata - A RulesDataSnapshot for the new data being written to Firebase at the location of this expression.
- root - A RulesDataSnapshot for the current data in Firebase at the root of your Firebase.
- now - Current time in milliseconds since the unix epoch.
- path - Can be used within a $foo Rules block to refer to the actual name of the child being read or written.