How do you extract route params, query params, and request body in a NestJS controller?

Q: How do you extract route params, query params, and request body in a NestJS controller?

@Get(':id') findOne( @Param('id') id: string, @Query('expand') expand: string, @Headers('authorization') auth: string, ) { return this.service.findOne(id, expand); } @Post() create(@Body() createDto: CreateUserDto) { return this.service.create(createDto); } @Param('key') — extracts a named route parameter. @Query('key') — extracts a named query string parameter. @Body() — extracts the full request body (or @Body('key') for a specific field). @Headers('key') — extracts a specific request header. @Req() — raw request object (Express/Fastify); avoid when possible. @Res() — raw response object; switches to library-specific mode (use passthrough: true to avoid side effects).

Difficulty: 4/10

Param decorators, DTO validation, Global pipes

Use @Param('id') for route parameters, @Query('page') for query strings, @Body() for the request body, and @Headers('authorization') for headers. @Req() and @Res() give access to the raw Express/Fastify objects but should be avoided when possible as they couple code to the underlying platform.

Extracting request data

Available parameter decorators:

1
@Param('key') — extracts a named route parameter.
2
@Query('key') — extracts a named query string parameter.
3
@Body() — extracts the full request body (or @Body('key') for a specific field).
4
@Headers('key') — extracts a specific request header.
5
@Req() — raw request object (Express/Fastify); avoid when possible.
6
@Res() — raw response object; switches to library-specific mode (use passthrough: true to avoid side effects).

Scenario Questions

0-2 years experience

Follow-up Questions