Table of Contents
- Introduction
- Prerequisites
- Setting Up the Project
- Creating the Microservice
- Adding Price Comparison Functionality
- Implementing the API Endpoints
- Testing the Microservice
-
Introduction
In this tutorial, we will learn how to develop a Go-based microservice for price comparison. We will build a simple microservice that fetches product prices from different online retailers and provides a comparison API endpoint. By the end of this tutorial, you will be able to create a Go-based microservice with price comparison functionality.
Prerequisites
To follow along with this tutorial, you should have basic knowledge of the Go programming language. You will also need the following software installed on your machine:
- Go programming language (version 1.14 or later)
- Text editor or Integrated Development Environment (IDE) of your choice
Setting Up the Project
Let’s start by setting up the project structure. Open your terminal or command prompt and create a new directory for your project. Navigate to the project directory and create the following files:
$ mkdir price_comparison_microservice
$ cd price_comparison_microservice
$ touch main.go
$ touch scraper.go
$ touch api.go
The main.go file will contain the main entry point of our microservice. The scraper.go file will handle fetching prices from different retailers, and the api.go file will handle the API endpoints.
Creating the Microservice
Open the main.go file in your text editor or IDE. Let’s start by importing the necessary packages:
package main
import (
"fmt"
"log"
"net/http"
)
Next, create the main function, which will be the entry point of our microservice:
func main() {
// TODO: Implement microservice logic
}
Inside the main function, we need to start the HTTP server that will handle the API requests. Add the following code:
func main() {
http.HandleFunc("/compare", handleCompare)
log.Fatal(http.ListenAndServe(":8080", nil))
}
The http.HandleFunc function is used to associate the /compare endpoint with the handleCompare function, which we will implement later. The http.ListenAndServe function starts the HTTP server on port 8080.
Adding Price Comparison Functionality
Open the scraper.go file in your text editor or IDE. This file will contain the logic to fetch prices from different retailers. Let’s start by importing the necessary packages:
package main
import (
"fmt"
)
Next, create a function named fetchPrice that takes a retailer name and returns the price:
func fetchPrice(retailer string) float64 {
// TODO: Implement price fetching logic
return 0.0
}
Inside the fetchPrice function, we will implement the logic to fetch the price from the specified retailer.
Implementing the API Endpoints
Open the api.go file in your text editor or IDE. This file will contain the logic to handle the API endpoints. Let’s start by importing the necessary packages:
package main
import (
"encoding/json"
"net/http"
)
Next, create a function named handleCompare that takes an HTTP response writer and an HTTP request as parameters:
func handleCompare(w http.ResponseWriter, r *http.Request) {
// TODO: Implement API endpoint logic
}
Inside the handleCompare function, we will implement the logic to handle the price comparison API endpoint.
To fetch prices from different retailers, we will define a struct named Product:
type Product struct {
Name string `json:"name"`
Retailer string `json:"retailer"`
Price float64 `json:"price"`
ComparisonUnit string `json:"comparison_unit"`
}
Next, we will create a slice of Product and populate it with sample data:
var products = []Product{
{Name: "Product 1", Retailer: "Retailer A", Price: 10.0, ComparisonUnit: "USD"},
{Name: "Product 2", Retailer: "Retailer B", Price: 15.0, ComparisonUnit: "USD"},
{Name: "Product 3", Retailer: "Retailer C", Price: 12.0, ComparisonUnit: "USD"},
// Add more sample products here
}
We will use this sample data to return the comparison results.
Inside the handleCompare function, parse the request URL query parameters and retrieve the product name:
func handleCompare(w http.ResponseWriter, r *http.Request) {
productName := r.URL.Query().Get("product")
}
Next, implement the logic to fetch prices from different retailers using the fetchPrice function we created earlier:
func handleCompare(w http.ResponseWriter, r *http.Request) {
productName := r.URL.Query().Get("product")
var results []Product
for _, p := range products {
// Fetch price from retailer and update the result
price := fetchPrice(p.Retailer)
p.Price = price
results = append(results, p)
}
// Convert results to JSON
jsonData, err := json.Marshal(results)
if err != nil {
http.Error(w, err.Error(), http.StatusInternalServerError)
return
}
// Set content type and write the JSON response
w.Header().Set("Content-Type", "application/json")
w.Write(jsonData)
}
In this code, we fetch prices from each retailer using the fetchPrice function. Then, we update the respective Product price field and add it to the results slice. Finally, we convert the results slice to JSON and write it as the response.
Testing the Microservice
To test the microservice, start the server by running the following command in your terminal or command prompt:
$ go run main.go
The microservice will start running on http://localhost:8080.
To test the /compare API endpoint, open your web browser or use a tool like cURL and send a GET request to http://localhost:8080/compare?product=Product+1. Replace Product+1 with the name of the product you want to compare.
You should see a JSON response containing the comparison results, including the product name, retailer, price, and comparison unit.
Conclusion
Congratulations! You have successfully developed a Go-based microservice for price comparison. In this tutorial, we learned how to set up the project, create the microservice, add price comparison functionality, implement the API endpoints, and test the microservice.
Now that you have a basic understanding, you can further enhance the microservice by integrating additional retailers, implementing caching mechanisms, or deploying it to a production environment.
Remember to explore the Go documentation and experiment with different features to deepen your knowledge of the language. Happy coding!