OAuth2 in NestJS for social login (Google, Facebook, Twitter, etc) /1

google-oauth.controller.ts

import { Controller, Get, Req, Res, UseGuards } from '@nestjs/common';
import { Request, Response } from 'express';
import { GoogleOauthGuard } from './google-oauth.guard';

@Controller('auth/google')
export class GoogleOauthController {
  constructor(private jwtAuthService: JwtAuthService) {}

  @Get()
  @UseGuards(GoogleOauthGuard)
  async googleAuth(@Req() _req) {
    // Guard redirects
  }

  @Get('redirect')
  @UseGuards(GoogleOauthGuard)
  async googleAuthRedirect(@Req() req: Request, @Res() res: Response) {
    // For now, we'll just show the user object
    return req.user;
  }
}

google-oauth.guard.ts

import { Injectable } from '@nestjs/common';
import { AuthGuard } from '@nestjs/passport';

@Injectable()
export class GoogleOauthGuard extends AuthGuard('google') {}

google-oauth.module.ts

import { Module } from '@nestjs/common';
import { GoogleOauthController } from './google-oauth.controller';
import { GoogleOauthStrategy } from './google-oauth.strategy';

@Module({
  imports: [],
  controllers: [GoogleOauthController],
  providers: [GoogleOauthStrategy],
})
export class GoogleOauthModule {}

google-oauth.strategy.ts

import { PassportStrategy } from '@nestjs/passport';
import { Profile, Strategy } from 'passport-google-oauth20';
import { Injectable } from '@nestjs/common';
import { ConfigService } from '@nestjs/config';

@Injectable()
export class GoogleOauthStrategy extends PassportStrategy(Strategy, 'google') {
  constructor(
    configService: ConfigService,
    private readonly usersService: UsersService,
  ) {
    super({
      // Put config in `.env`
      clientID: configService.get<string>('OAUTH_GOOGLE_ID'),
      clientSecret: configService.get<string>('OAUTH_GOOGLE_SECRET'),
      callbackURL: configService.get<string>('OAUTH_GOOGLE_REDIRECT_URL'),
      scope: ['email', 'profile'],
    });
  }

  async validate(
    _accessToken: string,
    _refreshToken: string,
    profile: Profile,
  ) {
    const { id, name, emails } = profile;

    // Here a custom User object is returned. In the the repo I'm using a UsersService with repository pattern, learn more here: https://docs.nestjs.com/techniques/database
    return {
      provider: 'google',
      providerId: id,
      name: name.givenName,
      username: emails[0].value,
    };
  }
}