Combining multiple guards in NestJS - Mini Project: Build & Apply

Combining Multiple Guards in NestJS

📖 Scenario: You are building a simple NestJS API that needs to protect a route with two guards: one to check if the user is authenticated, and another to check if the user has admin rights.This is like having two security guards at a door: one checks your ID, the other checks if you have a special pass.

🎯 Goal: Create a NestJS controller with a route protected by two guards combined using the @UseGuards() decorator.The route should only be accessible if both guards allow access.

📋 What You'll Learn

Create two guard classes: AuthGuard and AdminGuard

Create a controller called AppController with a route GET /protected

Apply both guards together on the /protected route using @UseGuards()

The guards should implement the CanActivate interface and return true or false accordingly

💡 Why This Matters

🌍 Real World

Combining multiple guards is common in real NestJS apps to layer security checks, like authentication and authorization.

💼 Career

Understanding how to combine guards helps you build secure APIs and is a key skill for backend developers working with NestJS.

1

Create the two guard classes

Create two guard classes called AuthGuard and AdminGuard. Each should implement the CanActivate interface from @nestjs/common and have a canActivate() method that returns true.

NestJS

import { CanActivate, ExecutionContext } from '@nestjs/common';

// Your code here

Need a hint?

Remember to import CanActivate and ExecutionContext from @nestjs/common.

2

Create the controller with a protected route

Create a controller class called AppController with a method getProtected() decorated with @Get('protected') from @nestjs/common. The method should return the string 'Protected content'.

NestJS

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

// Your code here

Need a hint?

Import Controller and Get from @nestjs/common and decorate the class and method properly.

3

Apply both guards to the protected route

Use the @UseGuards() decorator from @nestjs/common on the getProtected() method. Pass both AuthGuard and AdminGuard inside @UseGuards() to combine them.

NestJS

import { UseGuards } from '@nestjs/common';

// Add @UseGuards(AuthGuard, AdminGuard) above getProtected()
// Your code here

Need a hint?

Import UseGuards and add @UseGuards(AuthGuard, AdminGuard) above the getProtected() method.

4

Export the controller and guards for use

Add export keywords to the AppController, AuthGuard, and AdminGuard classes so they can be used in other parts of the application.

NestJS

// Your code here

Need a hint?

Make sure all classes have the export keyword before class.