How do I get a request header using NestJS? - nestjs

Question

I have a simple app that returns Something: Value as a header. I currently have the following as a controller...
import { Controller, Get, Header } from "#nestjs/common";
#Controller("health")
export class HealthController {
#Get()
#Header("content-type", "application/json")
checkHealth(): unknown {
return {
test: "This is the test",
};
}
}
In express I would expect to be able to do something like req.headers but I am not sure how to do that in nestjs.

Answer 1

You should pass Headers from #nestjs/common as an argument to function:
import { Controller, Get, Headers } from "#nestjs/common";
#Controller("health")
export class HealthController {
#Get()
checkHealth(#Headers() headers: Record < string, string > ) {
return {
test: "This is the test",
};
}
}
If you need just one header you can pass it's name to header like this:
#Headers('content-type') headers: string.
Alternatively if you want access to express req object you can also pass it to your controller
import { Controller, Get, Req } from "#nestjs/common";
import { Request } from 'express';
#Controller("health")
export class HealthController {
#Get()
checkHealth(#Req() req: Request) {
return {
test: "This is the test",
};
}
}

Answer 2

You have two options to get the headers. You can use #Req() req in the route handler and then get req.headers, or you can use #Headers() headers in the route handler and then headers is the same as req.headers
import { Controller, Get, Header, Headers } from "#nestjs/common";
import { Request } from 'express';
// OR
import { FastifyRequest } from 'fastify'
#Controller("health")
export class HealthController {
#Get()
#Header("content-type", "application/json")
checkHealth(#Req() req: Request | FastifyRequest): unknown { // remove which isn't used here
console.log(req.headers);
return {
test: "This is the test",
};
}
}
Or
import { Controller, Get, Header, Headers } from "#nestjs/common";
#Controller("health")
export class HealthController {
#Get()
#Header("content-type", "application/json")
checkHealth(#Headers() headers: Record<string, string>): unknown {
console.log(headers);
return {
test: "This is the test",
};
}
}

Answer 3

You can create a decorator to pull out the headers from the request context.
export const RequestHeaders = createParamDecorator(
async (ctx: ExecutionContext) => {
// extract headers
const headers = ctx.switchToHttp().getRequest().headers;
return headers;
},
and when used in a controller:
#Post('/route')
async controllerMethod(#RequestHeaders() headers) {
console.log(headers)
// returns all headers in incoming request
}
shamelessly stolen from this answer, thank you to whoever wrote it: https://github.com/nestjs/nest/issues/4798#issuecomment-706176390