Weather Forecast Service

A comprehensive NestJS-based weather forecast API that provides current weather data and forecasts for cities worldwide using the OpenWeatherMap API.

Features

• Real-time current weather data
• 5-day weather forecasts with 3-hour intervals
• City search tracking and statistics
• Scheduled background data refresh
• SQLite database with TypeORM
• Comprehensive API documentation with Swagger
• Input validation and error handling
• CORS enabled for cross-origin requests

Tech Stack

• Framework: NestJS with TypeScript
• Database: SQLite with TypeORM
• External API: OpenWeatherMap API
• Documentation: Swagger/OpenAPI
• Validation: class-validator
• Scheduling: @nestjs/schedule
• HTTP Client: Axios

Prerequisites

• Node.js (v16 or higher)
• npm or yarn
• OpenWeatherMap API key

Installation

1. Clone the repository

git clone <repository-url>
cd weather_forecast_service

2. Install dependencies

npm install

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

OPENWEATHER_API_KEY=your_openweathermap_api_key_here
PORT=3000

4. Build the application

npm run build

5. Start the application

npm start

The server will start on http://localhost:3000

API Endpoints

Weather Endpoints

• GET /api/weather/current?city={cityName} - Get current weather for a city
• GET /api/weather/forecast?city={cityName} - Get 5-day weather forecast
• GET /api/weather/history - Get search history
• GET /api/weather/cities - Get all tracked cities

Dashboard Endpoints

• GET / - Main dashboard page
• POST /search - Search functionality

API Documentation

Interactive API documentation is available at:

http://localhost:3000/api/docs

Database Schema

The application uses four main entities:

CityEntity

• Stores city information with coordinates
• Tracks search statistics
• Primary reference for weather data

WeatherEntity

• Current weather data for cities
• Linked to CityEntity via foreign key
• Automatically updated on API calls

ForecastEntity

• Weather forecast data points
• 3-hour interval forecasts up to 5 days
• Linked to CityEntity

SearchHistoryEntity

• Tracks search patterns
• Records search frequency and timestamps

Caching Strategy

• Current Weather: Cached for 15 minutes
• Forecast Data: Cached for 1 hour
• Background Refresh: Scheduled hourly updates for popular cities

Error Handling

The API provides comprehensive error responses:

• 200 OK - Success
• 400 Bad Request - Invalid input or API key issues
• 404 Not Found - City not found
• 500 Internal Server Error - Server errors

Development

Available Scripts

• npm start - Start production server
• npm run start:dev - Start development server with hot reload
• npm run build - Build the application
• npm run test - Run tests
• npm run lint - Run ESLint

Project Structure

src/
├── controllers/         # API controllers
├── services/           # Business logic services
├── entities/           # Database entities
├── dto/               # Data transfer objects
├── app.module.ts      # Main application module
└── main.ts           # Application entry point

Configuration

Environment Variables

• OPENWEATHER_API_KEY - Required: Your OpenWeatherMap API key
• PORT - Optional: Server port (default: 3000)

Database

The application uses SQLite by default. The database file is automatically created as weather.db in the project root.

Performance Considerations

• Database queries are optimized to prevent N+1 query problems
• API responses are cached to reduce external API calls
• Background tasks refresh popular city data proactively
• Proper indexing on frequently queried fields

Security

• Input validation on all endpoints
• Environment variable protection for API keys
• CORS configuration for secure cross-origin access
• Error messages sanitized to prevent information leakage

Monitoring and Logging

• Morgan middleware for HTTP request logging
• Structured logging for debugging and monitoring
• Error tracking with detailed stack traces in development