What are some examples of Firebase security rules?

What are some examples of Firebase security rules?

Firebase security rules are used to control access to your database. For example, you can allow read access only to authenticated users.

Can you give me a specific example of a rule for a chat application?

Sure! You can use a rule like this:

{
  "rules": {
    ".read": "auth != null",
    ".write": "auth != null",
    "messages": {
      "$messageId": {
        ".read": "auth != null",
        ".write": "auth.uid === data.child('userId').val()"
      }
    }
  }
}

This allows users to read messages but only write their own.

What if I want to restrict access based on user roles?

You can define roles in your database and use them in your rules. For example:

{
  "rules": {
    "users": {
      "$userId": {
        ".read": "auth != null && auth.uid === $userId || root.child('roles').child(auth.uid).val() === 'admin'",
        ".write": "auth != null && auth.uid === $userId"
      }
    }
  }
}

This allows users to read their own data and gives admins access to all user data.