Why guards control access in NestJS - Quick Recap

Recall & Review

beginner

What is the main purpose of guards in NestJS?

Guards control access by deciding if a request can proceed based on conditions like user roles or authentication status.

beginner

How do guards help protect routes in a NestJS application?

Guards check requests before they reach route handlers, blocking unauthorized users from accessing protected resources.

intermediate

Which interface must a guard implement in NestJS?

A guard must implement the CanActivate interface, which requires a canActivate() method to decide access.

intermediate

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

It returns a boolean or a Promise/Observable resolving to a boolean: true to allow access, false to deny.

intermediate

Why is it important to use guards instead of checking access inside controllers?

Guards centralize access logic, making code cleaner, reusable, and easier to maintain compared to scattered checks in controllers.

What does a NestJS guard primarily control?

A Logging requests

B Access to routes and resources

C UI rendering

D Database connections

Guards control access by deciding if a request can proceed to a route or resource.

Which method must a NestJS guard implement?

A checkAccess()

B handleRequest()

C validateUser()

D canActivate()

The canActivate() method determines if access is allowed.

What should canActivate() return to allow access?

A true

B null

C false

D undefined

Returning true allows the request to proceed.

Why use guards instead of checking access inside controllers?

A Guards centralize access logic

B Guards are slower

C Controllers cannot check access

D Guards handle database queries

Guards keep access control logic in one place for cleaner code.

Can guards perform asynchronous checks?

A Only with callbacks

B No, only synchronous

C Yes, by returning a Promise or Observable

D Only with setTimeout

Guards can return Promises or Observables for async access checks.

Explain how guards control access in a NestJS application and why they are useful.

Think about how guards act like gatekeepers before reaching route handlers.

Describe the role of the canActivate() method in a NestJS guard.

Focus on what canActivate() decides and what it returns.