@udemy/common

A shared package containing common utilities, guards, decorators, constants, and interfaces for the Course Platform microservices architecture.

Installation

npm install @udemy/common

Features

Guards

• RoleGuard: Authentication and authorization guard that validates JWT tokens and checks user roles and permissions
• Supports both REST and GraphQL contexts

Decorators

• @Auth(): Protects routes with required permissions
• @Roles(): Specifies required roles for route access
• @CurrentUser(): Injects the current user from the request context

Constants

• Enums: User roles, permissions, course levels, and request statuses
• Role-Permissions Mapping: Defines which permissions each role has
• Pagination: Default limit and page values
• Messages: Common error and validation messages

Interfaces

• Common TypeScript interfaces for user, JWT, and context objects

Usage

Basic Authentication

import { Auth, CurrentUser } from '@udemy/common';

@Resolver()
export class UserResolver {
  @Query(() => User)
  @Auth()
  getProfile(@CurrentUser() user: any) {
    return user;
  }
}

Role-Based Access

import { Roles, Role } from '@udemy/common';

@Resolver()
export class AdminResolver {
  @Mutation(() => User)
  @Roles(Role.ADMIN)
  createUser(@Args('input') input: CreateUserInput) {
    // Only ADMIN role can access this
  }
}

Permission-Based Access

import { Auth, Permission } from '@udemy/common';

@Resolver()
export class CourseResolver {
  @Mutation(() => Course)
  @Auth([Permission.CREATE_COURSE])
  createCourse(@Args('input') input: CreateCourseInput) {
    // Requires CREATE_COURSE permission
  }
}

Available Roles

• ADMIN: Full system access with all permissions
• INSTRUCTOR: Can create and manage courses
• USER: Basic user permissions for learning and purchases

Available Permissions

User Management

• UPDATE_USER, DELETE_USER, EDIT_USER_ROLE, VIEW_USER, CREATE_INSTRUCTOR

Authentication

• RESET_PASSWORD, CHANGE_PASSWORD, FORGOT_PASSWORD, LOGOUT

Category Management

• CREATE_CATEGORY, UPDATE_CATEGORY, DELETE_CATEGORY

Course Management

• CREATE_COURSE, UPDATE_COURSE, DELETE_COURSE

Request Management

• CREATE_REQUEST, UPDATE_REQUEST, DELETE_REQUEST, VIEW_REQUEST

Certificate Management

• CREATE_CERTIFICATE, VIEW_CERTIFICATE, DELETE_CERTIFICATE

Shopping Features

• CART operations: CREATE_CART, UPDATE_CART, DELETE_CART, VIEW_CART
• WISHLIST operations: CREATE_WISHLIST, DELETE_WISHLIST, VIEW_WISHLIST
• REVIEW operations: CREATE_REVIEW, UPDATE_REVIEW, DELETE_REVIEW

Configuration

The RoleGuard requires these environment variables:

JWT_SECRET=your-jwt-secret-key

Dependencies

• @nestjs/common
• @nestjs/core
• @nestjs/graphql
• @nestjs/jwt
• @nestjs/passport
• nestjs-i18n
• passport
• passport-jwt
• typeorm
• reflect-metadata

Development

Building the Package

npm run build

Watch Mode

npm run dev

Integration with Services

In your service module:

import { RoleGuard } from '@udemy/common';

@Module({
  providers: [
    {
      provide: APP_GUARD,
      useClass: RoleGuard,
    },
  ],
})
export class AppModule {}

Required Dependencies in Service:

Make sure your service has these dependencies installed:

npm install @nestjs/jwt @nestjs/passport passport-jwt nestjs-i18n

Error Messages

Common error messages included in the package:

• "User not found in request"
• "Password should be from 6 to 16 digits"
• "An error occurred"

Pagination

Default pagination constants:

import { LIMIT, PAGE } from '@udemy/common';

// LIMIT = 12
// PAGE = 1

License

This package is part of the Course Platform microservices architecture.