Role-based guards in NestJS - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a role-based guard in NestJS?

A role-based guard in NestJS is a piece of code that checks if a user has the right role to access a certain part of the application. It helps protect routes by allowing only users with specific roles to proceed.

beginner

How do you apply a role-based guard to a route in NestJS?

You apply a role-based guard by using the @UseGuards() decorator on a controller or route handler and passing the guard class that checks user roles.

intermediate

What is the purpose of the CanActivate interface in NestJS guards?

The CanActivate interface defines a method called canActivate() that returns true or false to allow or deny access. Role-based guards implement this interface to check user roles before allowing access.

intermediate

How can you pass roles to a role-based guard in NestJS?

You can pass roles using a custom decorator that stores roles as metadata on the route. The guard then reads this metadata to check if the user has one of the required roles.

beginner

Why is role-based guarding important in web applications?

Role-based guarding helps keep parts of an app safe by making sure only users with the right permissions can access sensitive data or actions. It supports security and proper user management.

Which NestJS interface must a role-based guard implement?

A PipeTransform

B OnModuleInit

C ExceptionFilter

D CanActivate

Role-based guards implement the CanActivate interface to decide if a request can proceed.

How do you specify which roles can access a route?

A By setting roles in the main.ts file

B By hardcoding roles inside the guard only

C By using a custom decorator that sets roles metadata

D By using the @Injectable decorator

A custom decorator sets roles as metadata on routes, which the guard reads to check access.

What does the canActivate() method return to allow access?

A true

B null

C undefined

D false

Returning true from canActivate() means access is allowed.

Where do you apply a role-based guard in NestJS?

A In the database schema

B On controllers or route handlers using @UseGuards()

C Inside the service classes

D Only in the main application bootstrap

Guards are applied on controllers or routes with the @UseGuards() decorator.

What is the main benefit of using role-based guards?

A To restrict access based on user roles

B To speed up database queries

C To style the user interface

D To log user activity

Role-based guards restrict access to routes depending on user roles.

Explain how role-based guards work in NestJS and how you implement them.

Think about how NestJS checks if a user can access a route based on their role.

Describe why role-based guards are important for application security.

Consider what happens if anyone could access all parts of an app.