Header

Kind: Function

Source: packages/common/decorators/http/header.decorator.ts

Part of: Common

Request method Decorator. Sets a response header.

For example: @Header('Cache-Control', 'none') @Header('Cache-Control', () => 'none')

Header is a request method decorator that configures an HTTP response header for a route handler. Apply it to controller methods to set a static header value or compute the value dynamically when the request is handled.

Signature

ts
function Header(name: string, value: string | (() => string)): MethodDecorator

Parameters

Returns: MethodDecorator

Diagram

mermaid
graph LR
  A[Incoming HTTP Request] --> B[Controller Route Handler]
  B --> C[@Header Decorator Metadata]
  C --> D[Response Header Applied]
  D --> E[HTTP Response]

Usage

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

@Controller('reports')
export class ReportsController {
  @Get('cached')
  @Header('Cache-Control', 'public, max-age=3600')
  getCachedReport() {
    return { status: 'ok' };
  }

  @Get('dynamic')
  @Header('Cache-Control', () => 'no-store')
  getDynamicReport() {
    return { status: 'ok' };
  }
}

AI Coding Instructions

• Apply @Header() to route handler methods, alongside decorators such as @Get(), @Post(), or other HTTP method decorators.
• Use a string value for headers that are known at declaration time, such as Content-Type or Cache-Control.
• Use a callback value when the header must be resolved dynamically during request handling.
• Ensure header names and values comply with HTTP header conventions; avoid setting restricted or conflicting headers unintentionally.
• Prefer framework response metadata decorators like @Header() over manually mutating the response object when the value does not require imperative response handling.

Used by

4 references from 4 files. Each is a place in this repository where the symbol is actually used — go read one rather than trusting an example.

Imported by (4)

• ErrorsController — integration/hello-world/src/errors/errors.controller.ts:3
• HelloController — integration/hello-world/src/hello/hello.controller.ts:6
• HostController — integration/hello-world/src/host/host.controller.ts:6
• HostArrayController — integration/hello-world/src/host-array/host-array.controller.ts:6