Create a document only if it doesn't exist in Firebase Firestore

Question

What I am trying to achieve is very simple. I need to create a user entry in the database only if it doesn\'t exist.

The app flow:

1. Create a

Answer 1

Use logic in your code, but not in rules. Add addOnCompleteListener to user collection and after get the result do some actions.

getUsers.document(userUID).get().addOnCompleteListener(new OnCompleteListener() {
@Override
public void onComplete(@NonNull Task doc) {
     if(!doc.getResult().exists()){
        //add new user
    }
}                       

}

Rules:

match /UsersProfile/{document=**} {
  allow read, write: if request.auth != null;
}