Restrict access to Firebase-Database with auth.uid not working

Question

I want to restrict access to my Firebase Database, so that only the users I authorize can write to it. But the solution almost everywhere proposed doesn't seem to work for me.

I always get an 401 (unathorized) Error in my Console.

I tried two ways of checking wheter the right user is logged in or not, but none of them worked for me.:

1. uid hard-coded in rules:

{
"rules": {
  ".read": true,
  ".write": "auth.uid === 'UID'")",
    }
}

2. uid in database

{
"rules": {
  ".read": true,
  ".write": "root.child('users').hasChild(auth.uid)",
    }
}

In both ways I used the uid provided in the Firebase-Authentication overview. I use Google as Signin provider.

Answer 1

From the documentation:

Here's an example of a rule that grants write access for authenticated users to /users/<uid>/, where <uid> is the ID of the user obtained through Firebase Authentication.

---

Edit:

For a specific path and current obtained user through Firebase Authentication, this should help:

{
  "rules": {
    "YourSpecificPath": {

     "$uid": { // where <uid> is the ID of the user obtained through Firebase Authentication
        ".write": "$uid === auth.uid"    
        ".read": true,

      }
    }
  }
}

Or, give the uid directly:

{
  "rules": {
    ".read": true,
    ".write": "auth.uid === 'dJrGShfgfd2'"
  }
}