Weather_Tracker_App in Golang

As developers, we often build tools to simplify our lives or provide valuable information. The Golang Weather Tracker App, available on GitHub, is a prime example of such a tool. This command-line application, built with the efficiency of Go, allows you to quickly retrieve weather information for any city, making it a handy utility for anyone wanting a quick weather update.

This article will delve into the specifics of this project, exploring its features, the underlying Go code, and potential areas for expansion.

Core Functionality at a Glance

The Weather Tracker App is designed to be straightforward and user-friendly. Its core functionality includes:

City-Specific Weather Lookup: Users can input the name of any city, and the application will fetch and display its current weather conditions.
Essential Weather Details: The app provides key information such as:
- Weather Description: A brief summary of the current weather (e.g., “Clear sky,” “Rain”).
- Temperature: The current temperature in Celsius.
- Humidity: The current humidity percentage.
Simple Command-Line Interface: The application is accessed via the command line, making it lightweight and efficient.

Exploring the Code

While the current Weather Tracker App is a single-file application, envisioning how it could be structured with separate folders for models, routers, and the main application logic can be beneficial for understanding software architecture and how to scale projects.

Folder Structure:

Weather_Tracker_App/
├── app/
│ └── app.go
├── models/
│ └── weather.go
├── routers/
│ └── weather_router.go
├── main.go
└── go.mod

Explanation of the Hypothetical Structure:

models/ Folder:

This folder would contain the data structures (models) used throughout the application.

In the context of the Weather Tracker App, models/weather.go would define the WeatherData struct:

// models/weather.go
package models

type WeatherData struct {
    Name string `json:"name"`
    Main struct {
        Temp     float64 `json:"temp"`
        Humidity int     `json:"humidity"`
    } `json:"main"`
    Weather []struct {
        Description string `json:"description"`
    } `json:"weather"`
}

routers/ Folder:

This folder would handle the routing of requests, especially relevant if the application were a web service.

For the command-line application, this concept is less direct, but we can think of routers/weather_router.go as handling the logic for fetching and presenting weather data. It might contain a function that takes a city name and returns the formatted weather information.

// routers/weather_router.go
package routers

import (
    "encoding/json"
    "fmt"
    "io/ioutil"
    "net/http"

    "your_module_path/models" // Replace with your actual module path
)

const apiKey = "YOUR_API_KEY" // Replace with your actual API key
const baseURL = "https://api.openweathermap.org/data/2.5/weather"

func GetWeatherData(city string) (*models.WeatherData, error) {
    url := fmt.Sprintf("%s?q=%s&appid=%s&units=metric", baseURL, city, apiKey)
    resp, err := http.Get(url)
    if err != nil {
        return nil, fmt.Errorf("failed to fetch weather data: %w", err)
    }
    defer resp.Body.Close()

    if resp.StatusCode != http.StatusOK {
        return nil, fmt.Errorf("API request failed with status code: %d", resp.StatusCode)
    }

    body, err := ioutil.ReadAll(resp.Body)
    if err != nil {
        return nil, fmt.Errorf("failed to read response body: %w", err)
    }

    var data models.WeatherData
    err = json.Unmarshal(body, &data)
    if err != nil {
        return nil, fmt.Errorf("failed to unmarshal JSON: %w", err)
    }

    return &data, nil
}

func FormatWeatherData(data *models.WeatherData) string {
    return fmt.Sprintf("Weather for %s:\n  Description: %s\n  Temperature: %.2f °C\n  Humidity: %d%%\n",
        data.Name, data.Weather[0].Description, data.Main.Temp, data.Main.Humidity)
}

app/ Folder:

This folder would contain the core application logic, orchestrating the different parts of the application.

app/app.go might handle the command-line argument parsing and call the appropriate functions from the routers package.

// app/app.go
package app

import (
    "fmt"
    "os"

    "your_module_path/routers" // Replace with your actual module path
)

func Run() {
    if len(os.Args) != 2 {
        fmt.Println("Usage: go run main.go <city_name>")
        return
    }
    city := os.Args[1]

    weatherData, err := routers.GetWeatherData(city)
    if err != nil {
        fmt.Println("Error:", err)
        return
    }

    output := routers.FormatWeatherData(weatherData)
    fmt.Println(output)
}

main.go:
- The main.go file would become very simple, acting as the entry point that calls the Run function in the app package.
  Go
  // main.go package main func main() { app.Run() }

Benefits of this Structure:

Organization: Separating concerns into different folders makes the codebase easier to navigate and understand, especially as the application grows.
Modularity: Each component (models, routers, app logic) can be developed and tested independently.
Scalability: This structure makes it easier to add new features or modify existing ones without affecting the entire codebase.
Maintainability: A well-organized codebase is easier to maintain and debug.

Exploring the Code

Let’s take a closer look at the key components of the Go code that powers this application:

main.go – The Heart of the Application: This file contains the entry point of the program. It handles:
- Command-Line Argument Parsing: The main function checks if a city name is provided as a command-line argument. This is how the user specifies which city’s weather they want to see.
- API Interaction: The code makes an HTTP GET request to a weather API (likely OpenWeatherMap, given the common usage of this API in such projects).
- Data Handling: The JSON response from the API is parsed into Go structs, allowing the application to extract the relevant weather data.
- Output Formatting: The retrieved information is then formatted and displayed to the user in a clear and readable manner.
API Integration: The application leverages Go’s net/http package to make requests to the weather API. The URL is constructed dynamically based on the city name and the API key.
JSON Parsing: The encoding/json package is crucial for handling the JSON response from the API. The WeatherData struct maps the JSON fields to Go variables, making it easy to work with the data.

Setting Up and Running the Application

To use the Weather Tracker App, follow these steps:

Clone the Repository:

git clone https://github.com/alurijayaprakash/Golang-Playground.git
cd Golang-Playground/BasicProjects/11.Weather_Tracker_App

Build the Application:
```
go build .
```
Run the Application:
```
./Weather_Tracker_App <city_name>
```
Replace <city_name> with the city you want to check the weather for.

Tags: Golang

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Weather_Tracker_App in Golang

This article explores the development of a weather tracker application using the Go programming language

Jayaprakash Aluri

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