How do you compose multiple decorators into a single reusable decorator in NestJS?

Q: How do you compose multiple decorators into a single reusable decorator in NestJS?

import { applyDecorators } from '@nestjs/common'; export function Auth(...roles: string[]) { return applyDecorators( UseGuards(JwtAuthGuard, RolesGuard), Roles(...roles), ApiBearerAuth(), ApiUnauthorizedResponse({ description: 'Unauthorized' }), ); } // Before — verbose and repetitive on every protected route @UseGuards(JwtAuthGuard, RolesGuard) @Roles('admin') @ApiBearerAuth() @ApiUnauthorizedResponse({ description: 'Unauthorized' }) @Delete(':id') remove() {} // After — single intention-revealing decorator @Auth('admin') @Delete(':id') remove() {} Accepts any combination of method and class decorators. Decorators are applied in the order listed — first in the array runs first. Works for both method-level and class-level composition. Ideal for bundling auth + Swagger + metadata decorators that always go together. The composed decorator has a meaningful name — @Auth('admin') communicates intent better than 4 separate decorators.

Difficulty: 6/10

custom decorators, metadata composition, dependency injection

Use applyDecorators() to bundle multiple decorators — including guards, metadata decorators, and Swagger decorators — into one named decorator. This reduces boilerplate on routes and co-locates all related concerns under a single, intention-revealing name like @Auth() or @ApiPaginatedResponse().

@Auth() composite decorator using applyDecorators

applyDecorators() design guidance:

1
Accepts any combination of method and class decorators.
2
Decorators are applied in the order listed — first in the array runs first.
3
Works for both method-level and class-level composition.
4
Ideal for bundling auth + Swagger + metadata decorators that always go together.
5
The composed decorator has a meaningful name — @Auth('admin') communicates intent better than 4 separate decorators.

Scenario Questions

0-2 years experience

Follow-up Questions