Redirect responses in NestJS - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What does this NestJS controller method do?

Consider this NestJS controller method:

  @Get('old-route')
  redirectToNew(@Res() res: Response) {
    return res.redirect('/new-route');
  }

What happens when a client requests /old-route?

NestJS

import { Controller, Get, Res } from '@nestjs/common';
import { Response } from 'express';

@Controller()
export class AppController {
  @Get('old-route')
  redirectToNew(@Res() res: Response) {
    return res.redirect('/new-route');
  }
}

A The server throws a runtime error because @Res() is used incorrectly.

B The client receives a 404 Not Found error.

C The client receives the content of '/new-route' without redirect.

D The client receives a 302 redirect to '/new-route'.

💡 Hint

Think about what res.redirect() does in Express.

The res.redirect() method sends a 302 HTTP response telling the client to request the new URL. NestJS uses Express under the hood, so this behavior applies.

📝 Syntax

intermediate

Which option correctly uses NestJS decorators to redirect?

Which of the following NestJS controller methods correctly sends a redirect response using decorators without accessing @Res()?

A

@Get('go')
redirect() {
  return { url: '/target' };
}

B

@Get('go')
redirect(@Res() res: Response) {
  res.redirect('/target');
}

C

@Get('go')
@Redirect('/target')
redirect() {
  return;
}

D

@Get('go')
@Redirect('/target')
redirect() {
  return '/target';
}

💡 Hint

Look for the official NestJS way to redirect using decorators.

The @Redirect() decorator tells NestJS to send a redirect response. Returning nothing inside the method works fine. Returning a string or object without the decorator won't trigger a redirect.

🔧 Debug

advanced

Why does this redirect not work as expected?

Given this NestJS controller method:

  @Get('start')
  start(@Res() res: Response) {
    res.redirect('/end');
    return 'done';
  }

What is the problem with this code?

NestJS

import { Controller, Get, Res } from '@nestjs/common';
import { Response } from 'express';

@Controller()
export class AppController {
  @Get('start')
  start(@Res() res: Response) {
    res.redirect('/end');
    return 'done';
  }
}

A The redirect URL '/end' is invalid and causes a 404.

B The method sends two responses, causing an error.

C The method works fine and redirects correctly.

D The return statement is ignored, so the client gets no response.

💡 Hint

Think about what happens when you call res.redirect() and then return a value.

Calling res.redirect() sends a response immediately. Returning a value after that tries to send another response, which causes an error because HTTP only allows one response per request.

❓ state_output

advanced

What is the HTTP status code sent by this redirect?

Consider this NestJS controller method:

  @Get('go')
  @Redirect('/final', 301)
  go() {
    return;
  }

What HTTP status code will the client receive?

NestJS

import { Controller, Get, Redirect } from '@nestjs/common';

@Controller()
export class AppController {
  @Get('go')
  @Redirect('/final', 301)
  go() {
    return;
  }
}

A 301 Moved Permanently

B 302 Found

C 200 OK

D 404 Not Found

💡 Hint

Check the second argument of the @Redirect() decorator.

The second argument to @Redirect() sets the HTTP status code. Here it is 301, which means a permanent redirect.

🧠 Conceptual

expert

Why should you avoid mixing @Res() and return values in NestJS redirects?

In NestJS, what is the main reason to avoid using @Res() to send a redirect and also returning a value from the same controller method?

A Because using <code>@Res()</code> disables NestJS automatic response handling, so returning a value will cause an error.

B Because <code>@Res()</code> only works with JSON responses, not redirects.

C Because returning a value after <code>@Res()</code> causes the redirect URL to be ignored.

D Because NestJS requires all redirects to be handled by <code>@Redirect()</code> decorator only.

💡 Hint

Think about how NestJS handles responses when @Res() is injected.

When you use @Res(), NestJS expects you to handle the entire response yourself. Returning a value in addition causes NestJS to try sending a second response, which leads to errors.