Realtime Database security rules in Firebase - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the main purpose of Realtime Database security rules in Firebase?

They control who can read or write data in the database, protecting data from unauthorized access.

beginner

How do you specify read and write permissions in Realtime Database security rules?

Using the read and write properties inside rules, set to true or false or expressions that evaluate to boolean.

beginner

What does auth != null mean in a security rule?

It means the user must be signed in (authenticated) to pass the rule and access the data.

intermediate

Why is it important to test your Realtime Database security rules?

To make sure only authorized users can access or change data, preventing data leaks or unwanted changes.

beginner

What happens if no security rules are set in Realtime Database?

By default, the database is locked and no one can read or write data until rules allow it.

In Firebase Realtime Database rules, what does auth != null check?

A User is signed in

B User is an admin

C User has read permission

D User is offline

The expression auth != null means the user must be authenticated (signed in).

Which property controls write access in Realtime Database security rules?

A access

B read

C write

D update

The write property defines who can write or change data.

What is the default access level if no rules are set in Firebase Realtime Database?

A Full public access

B Write-only access

C Read-only access

D No access for anyone

By default, the database denies all reads and writes until rules allow access.

How can you allow only the owner of a data node to write to it?

A Allow write only on weekends

B Check if <code>auth.uid</code> matches the data owner ID

C Use <code>read: true</code> instead

D Set <code>write: true</code> globally

You compare auth.uid with the owner ID stored in data to restrict write access.

Why should you avoid setting read and write to true for all users?

A It exposes your data to anyone, risking security

B It makes the database slower

C It costs more money

D It disables authentication

Allowing all users to read and write can expose sensitive data and cause security breaches.

Explain how Firebase Realtime Database security rules control access to data.

Think about who can read or write data and how rules check user identity.

Describe a simple rule that allows only signed-in users to read and write their own data.

Use auth.uid and data path matching in rules.