firebase - Firestore security rule: How to ensure uniqueness of values in document?

Question

Can the below security rule ensure uniqueness of firstName, lastName, username, and email before creating a document in profiles collection?

match /profiles/{document=**} {
   allow create: if request.auth.uid != null
   && (request.resource.data.firstName is string && resource.data.firstName != request.resource.data.firstName)
   && (request.resource.data.lastName is string && resource.data.firstName != request.resource.data.firstName)
  && (request.resource.data.username is string && resource.data.username != request.resource.data.username)
  && (request.resource.data.email is string && resource.data.email != request.resource.data.email)
}

For example, below is the data in Firestore collection profiles

{
   "document1":{
      "firstName":"Jek",
      "lastName":"Choo",
      "email":"[email protected]",
      "username":"jek"
   },
   "document2":{
      "firstName":"Cara",
      "lastName":"Choo",
      "email":"[email protected]",
      "username":"cara"
   }
}

I want to create the below new document, and this create access should be denied

{
   "document3":{
      "firstName":"Jek",
      "lastName":"Choo",
      "email":"[email protected]",
      "username":"jek"
   }
}

And I want to create the below new document, this should be allowed.

{
   "document4":{
      "firstName":"example",
      "lastName":"com",
      "email":"[email protected]",
      "username":"example"
   }
}

In conclusion, can the above firestore security rule help to ensure field value uniqueness before a document is allowed to be created?

Answer 1

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