I want to achieve something like this using nest.js: (something very similar with Spring framework)
@Controller('/test')
class TestController {
@Get()
get(@Principal() principal: Principal) {
}
}
After hours of reading documentation, I found that nest.js supports creating custom decorator. So I decided to implement my own @Principal
decorator. The decorator is responsible for retrieving access token from http header and get principal of user from my own auth service using the token.
import { createParamDecorator } from '@nestjs/common';
export const Principal = createParamDecorator((data: string, req) => {
const bearerToken = req.header.Authorization;
// parse.. and call my authService..
// how to call my authService here?
return null;
});
But the problem is that I have no idea how to get my service instance inside a decorator handler. Is it possible? And how? Thank you in advance
It is not possible to inject a service into your custom decorator.
Instead, you can create an AuthGuard
that has access to your service. The guard can then add a property to the request
object, which you can then access with your custom decorator:
@Injectable()
export class AuthGuard implements CanActivate {
constructor(private authService: AuthService) {}
async canActivate(context: ExecutionContext): Promise<boolean> {
const request = context.switchToHttp().getRequest();
const bearerToken = request.header.Authorization;
const user = await this.authService.authenticate(bearerToken);
request.principal = user;
// If you want to allow the request even if auth fails, always return true
return !!user;
}
}
import { createParamDecorator } from '@nestjs/common';
export const Principal = createParamDecorator((data: string, req) => {
return req.principal;
});
and then in your controller:
@Get()
@UseGuards(AuthGuard)
get(@Principal() principal: Principal) {
// ...
}
Note that nest offers some standard modules for authentication, see the docs .
You can use middlewar for all controller.
auth.middleware.ts
interface AccountData {
accId: string;
iat: number;
exp: number;
}
interface RequestWithAccountId extends Request {
accId: string;
}
@Injectable()
export class AuthMiddleware implements NestMiddleware {
constructor(private readonly authenticationService: AuthenticationService) {}
async use(req: RequestWithAccountId, res: Response, next: NextFunction) {
const token =
req.body.token || req.query.token || req.headers['authorization'];
if (!token) {
throw new UnauthorizedException();
}
try {
const {
accId,
}: AccountData = await this.authenticationService.verifyToken(token);
req.accId = accId;
next();
} catch (err) {
throw new UnauthorizedException();
}
}
}
Then create AccountId decorator
account-id.decorator.ts
import {
createParamDecorator,
ExecutionContext,
UnauthorizedException,
} from '@nestjs/common';
export const AccountId = createParamDecorator(
(data: unknown, ctx: ExecutionContext) => {
const req = ctx.switchToHttp().getRequest();
const token = req.accId;
if (!token) {
throw new UnauthorizedException();
}
return token;
},
);
Then apply AccountId decorator in your controller
your.controller.ts
@Get()
async someEndpoint(
@AccountId() accountId,
) {
console.log('accountId',accontId)
}
for NestJS v7
Create custom pipe
// parse-token.pipe.ts
import { ArgumentMetadata, Injectable, PipeTransform } from '@nestjs/common';
import { AuthService } from './auth.service';
@Injectable()
export class ParseTokenPipe implements PipeTransform {
// inject any dependency
constructor(private authService: AuthService) {}
async transform(value: any, metadata: ArgumentMetadata) {
console.log('additional options', metadata.data);
return this.authService.parse(value);
}
}
Use this pipe with property decorator
// decorators.ts
import { createParamDecorator, ExecutionContext } from '@nestjs/common';
import { ParseTokenPipe} from './parse-token.pipe';
export const GetToken = createParamDecorator((data: unknown, ctx: ExecutionContext) => {
return ctx.switchToHttp().getRequest().header.Authorization;
});
export const Principal = (additionalOptions?: any) => GetToken(additionalOptions, ParseTokenPipe);
Use this decorator with or without additional options
@Controller('/test')
class TestController {
@Get()
get(@Principal({hello: "world"}) principal) {}
}
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