How can I ban a User in Firebase realtime Database using the rules?

Question

I've created a list of banned users in my realtime Database and I want to make them impossible to log-in, I know I can use the database rules, but I don't know how, can someone help me?

This is my database structure:

/banned-users:
    /UserId1:True
    /UserId2:True

Those are my database rules:

{
    "rules": {
    ".read": true,
    ".write": true
      }

}

Answer 1

You need to reference data in other paths as follows:

{
  "rules": {
    "thepath": {
          ".read": "root.child('banned-users').child(auth.uid).val() !== true"
          ".write": "root.child('banned-users').child(auth.uid).val() !== true"
      }
    }
}

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Note that actually you don't "make them impossible to log-in", because this is not possible, but you prevent them writing to/reading from your database.