Backend Project

This project is a backend service built using modern technologies and powerful Node.js libraries. It employs modern architectures such as Dependency Injection and Decorators to ensure clean, maintainable, and scalable code.

Table of Contents

• Technologies Used
• Project Structure
• Setup and Installation
• API Documentation
• Logging
• Dependency Injection
• Routing
• Decorators
• Running the Project

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Technologies Used

Core Dependencies

• Express.js: A fast and minimalist web framework for Node.js, used to handle HTTP requests and routing.
• Mongoose: An ODM (Object Data Modeling) library for MongoDB, used to interact with the database.
• Typegoose: A wrapper for Mongoose that allows defining models using TypeScript classes and decorators.
• Inversify: A powerful dependency injection (DI) container for TypeScript and JavaScript, used to manage dependencies and promote modularity.
• Zod: A TypeScript-first schema validation library, used for validating input data.
• Pino: A fast and low-overhead logging library, used for structured logging.
• Swagger UI Express: A middleware to serve Swagger API documentation.

Development Dependencies

• @types/express: TypeScript definitions for Express.
• @types/mongoose: TypeScript definitions for Mongoose.
• pino-pretty: A prettifier for Pino logs to make them more readable during development.
• pino-mongodb: A transport for Pino to store logs in MongoDB.

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Project Structure

The project is organized into modules, with each module containing its own controllers, services, and models. The main components include:

• src/index.routes.ts: Handles route setup and registration.
• src/modules/: Contains application modules (e.g., user module).
• src/common/: Shared utilities, configurations, and types.
• src/exceptions/: Custom exception handlers.
• src/configs/: Configuration files for MongoDB, logging, etc.
• openapi.json: OpenAPI specification for API documentation.

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Setup and Installation

1. Clone the repository:

   git clone <repository-url>
   cd <project-folder>

2. Install dependencies:

   npm install

3. Set up environment variables: Create a .env file in the root directory and add the following variables:

   PORT=3000
   MONGODB_URI=<your-mongodb-uri>
   MONGODB_DATABASE=<your-database-name>
   

4. Start the server:

   npm start

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API Documentation

The API documentation is generated using Swagger and is available at /api-docs. The OpenAPI specification is defined in the openapi.json file.

To access the documentation:

1. Start the server.
2. Navigate to http://localhost:<PORT>/api-docs.

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Logging

The project uses Pino for structured logging. Logs are output in JSON format and can be prettified during development using pino-pretty. Additionally, logs can be stored in MongoDB using pino-mongodb.

Example log output:

{
  "level": "info",
  "time": 1633024800000,
  "msg": "Request received: GET /api/v1/users"
}

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Dependency Injection

Dependency Injection (DI) is implemented using Inversify. This allows for better modularity and testability by decoupling dependencies.

Example of DI setup:

import { Container } from 'inversify';
import { UserService } from '@modules/user/user.service';
import { UserController } from '@modules/user/user.controller';

const container = new Container();
container.bind<UserService>(UserService).toSelf();
container.bind<UserController>(UserController).toSelf();

export default container;

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Routing

Routes are dynamically registered using decorators and metadata reflection. The setupRoutes function scans controllers and registers routes based on the metadata.

Example route registration:

@Controller('/users')
class UserController {
  @Get('/')
  getUsers() {
    // Handle GET /api/v1/users
  }

  @Post('/')
  createUser() {
    // Handle POST /api/v1/users
  }
}

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Decorators

Custom decorators are used to define routes and metadata for controllers and methods. These decorators simplify route registration and make the code more declarative.

Example decorators:

@Controller('/users')
class UserController {
  @Get('/')
  getUsers() {
    // Handle GET /api/v1/users
  }

  @Post('/')
  @Middleware(someMiddleware)
  createUser() {
    // Handle POST /api/v1/users
  }
}

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Running the Project

1. Ensure MongoDB is running and accessible.
2. Start the server:

   npm start

3. The server will be available at http://localhost:<PORT>.