String functions in Cloud Firestore Rules

Question

I need to remove a plus signal at string returned by request.auth.phone_number. For that, I've tried to use the replace function, but I've received the following error: "Function not found error: Name: [replace].";

match /test/{id} {
  allow read, update, delete, create: if request.auth != null && (resource.data.items[request.auth.token.phone_number.replace('+', '')] == true || resource == null);
}

This works fine when I run at Realtime Database. For instance:

"tests": {
  "$uid": {
    ".write": "auth.uid.replace('+', '') === '5521999991234'"
  }
}   

Is there any way to use string functions like "contains(), replace(), toLowerCase()" and so on, in Cloud Firestore Databases?

Thanks

Answer 1

You could write a function like this :

function replace(string, replace, by) {
  return string.split(replace).join(by)
}

and use it so..

replace('+3312312345', '+', '')

in your example :

match /test/{id} {
  allow read, write: if request.auth != null && 
  (resource.data.items[replace(request.auth.token.phone_number, '+', '')] 
  == true || resource == null);
}

// below your rules
function replace(string, replace, by) {
  return string.split(replace).join(by)
}

Answer 2

Firestore security rules use a completely different language than Realtime Database.

You can see a list of all methods available on string objects in the API documentation. The only thing you are asking to do that's actually available is lower and matches.