Guards, Interceptors & Pipes

import { Controller, Get, Param, UseGuards, UseInterceptors, UsePipes, ValidationPipe } from "@nestjs/common";
import { AuthGuard } from "./auth.guard.js";
import { LoggingInterceptor } from "./logging.interceptor.js";
@Controller("users")
@UseGuards(AuthGuard)
@UseInterceptors(LoggingInterceptor)
export class UsersController {
  @Get(":id")
  @UsePipes(ValidationPipe)
  findOne(@Param("id") id: string) {
    return { id };
  }
}

// auth.guard.ts
import { CanActivate, ExecutionContext, Injectable, UnauthorizedException } from "@nestjs/common";
 
@Injectable()
export class AuthGuard implements CanActivate {
  canActivate(context: ExecutionContext): boolean {
    const req = context.switchToHttp().getRequest();
    const token = req.headers.authorization?.replace("Bearer ", "");
    if (!token) throw new UnauthorizedException();
    req.userId = "user-42";
    return true;
  }
}
 
// logging.interceptor.ts
import { Injectable, NestInterceptor, ExecutionContext, CallHandler } from "@nestjs/common";
import { Observable, tap } from "rxjs";
 
@Injectable()
export class LoggingInterceptor implements NestInterceptor {
  intercept(context: ExecutionContext, next: CallHandler): Observable<unknown> {
    const start = Date.now();
    const req = context.switchToHttp().getRequest();
    return next.handle().pipe(
      tap(() => console.log(`${req.method} ${req.url} ${Date.now() - start}ms`))
    );
  }
}
 
// roles.guard.ts
import { SetMetadata, Injectable, CanActivate, ExecutionContext } from "@nestjs/common";
import { Reflector } from "@nestjs/core";
export const ROLES_KEY = "roles";
export const Roles = (...roles: string[]) => SetMetadata(ROLES_KEY, roles);
 
@Injectable()
export class RolesGuard implements CanActivate {
  constructor(private reflector: Reflector) {}
  canActivate(context: ExecutionContext): boolean {
    const roles = this.reflector.get<string[]>(ROLES_KEY, context.getHandler());
    if (!roles) return true;
    const req = context.switchToHttp().getRequest();
    return roles.includes(req.userRole);
  }
}

// main.ts
app.useGlobalGuards(new AuthGuard());
app.useGlobalInterceptors(new LoggingInterceptor());
app.useGlobalPipes(new ValidationPipe({ whitelist: true }));