Table of Contents
Overview
In this tutorial, we will learn how to build a Go-based microservice for document conversion. We will create a web application that allows users to upload documents in various formats and convert them to a different format of their choice. By the end of this tutorial, you will have a fully functional microservice that can handle document conversion requests.
Prerequisites
Before we begin, you will need to have the following:
- Basic knowledge of Go programming language
- Go installed on your local machine
- Familiarity with RESTful APIs
- Understanding of JSON
Setup
To get started, let’s set up our project. Create a new directory for the project and initialize it as a Go module by running the following command:
$ go mod init document-conversion
This will create a go.mod file that tracks the project’s dependencies.
Next, let’s create the main file for our microservice:
$ touch main.go
Open main.go in your favorite text editor and let’s start building our microservice.
Creating the Microservice
The first step is to set up a basic HTTP server to handle incoming requests. Add the following code to main.go:
package main
import (
"log"
"net/http"
)
func main() {
http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
w.Write([]byte("Welcome to the Document Conversion Microservice"))
})
log.Fatal(http.ListenAndServe(":8080", nil))
}
This code sets up a simple handler for the root URL (“/”) and returns a welcome message. It also starts an HTTP server on port 8080.
To test the microservice, run the following command:
$ go run main.go
Now, if you visit http://localhost:8080 in your browser, you should see the welcome message.
Document Conversion
Now that we have a basic microservice set up, let’s add functionality for document conversion. For this tutorial, we will focus on converting PDF documents to HTML.
First, we need to add a new package to our project to handle the document conversion. Create a new directory called converter in the project root and create a file named converter.go inside it.
Add the following code to converter.go:
package converter
import (
"errors"
)
func ConvertToHTML(file []byte) ([]byte, error) {
// Convert the file to HTML
// Implement the conversion logic here
return nil, errors.New("conversion not implemented")
}
This code defines a function ConvertToHTML in the converter package that takes a byte slice representing the file content and returns a byte slice of the converted HTML content.
Next, we need to update our main.go file to handle document conversion requests. Replace the existing handler code with the following:
package main
import (
"log"
"net/http"
"./converter"
)
func main() {
http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
switch r.Method {
case "POST":
file, _, err := r.FormFile("file")
if err != nil {
http.Error(w, "Failed to get file", http.StatusBadRequest)
return
}
fileBytes, err := ioutil.ReadAll(file)
if err != nil {
http.Error(w, "Failed to read file", http.StatusInternalServerError)
return
}
converted, err := converter.ConvertToHTML(fileBytes)
if err != nil {
http.Error(w, "Failed to convert file", http.StatusInternalServerError)
return
}
w.Header().Set("Content-Disposition", "attachment; filename=result.html")
w.Write(converted)
default:
w.Write([]byte("Welcome to the Document Conversion Microservice"))
}
})
log.Fatal(http.ListenAndServe(":8080", nil))
}
This code adds a conditional statement to handle only POST requests. It retrieves the uploaded file, reads its contents, and calls the ConvertToHTML function from the converter package. If the conversion is successful, it sets the appropriate headers and returns the converted HTML file as the response.
Now, let’s test the document conversion feature. Start the microservice again using go run main.go and navigate to http://localhost:8080 in your browser.
Upload a PDF file using the provided file input field and click the submit button. The microservice will convert the PDF to HTML and prompt you to download the converted file.
Conclusion
In this tutorial, we learned how to build a Go-based microservice for document conversion. We set up a basic HTTP server using the net/http package and added functionality to convert PDF documents to HTML using a separate converter package.
By following this tutorial, you should now have a good understanding of how to create a Go-based microservice and handle document conversion requests. Feel free to explore additional document conversion formats or enhance the microservice with more features.
Please note that the converter package’s conversion logic is not implemented in this tutorial and returns an error. You will need to implement the actual conversion logic based on your requirements.
Remember to check the official Go documentation for more details and advanced features.
Happy coding!