Receiving Uploaded Files in Golang using net/http and Mux

Introduction
Building a server that handles file uploads is a common task in web development. In Golang, you can utilize the net/http package to efficiently manage file uploads. Here's a comprehensive guide on how to receive uploaded files in a Golang net/http server using the popular Mux router.

Implementing File Upload
To enable file upload functionality in your server, you need to make the following changes:

1. Create an endpoint that handles the incoming file upload requests. This endpoint should be defined in the router variable:

   router.
        Path("/upload").
        Methods("POST").
        HandlerFunc(UploadFile)

2. In the UploadFile function, you need to parse the multipart form data. This is where the uploaded file will be available:

   func UploadFile(w http.ResponseWriter, r *http.Request) {
    err := r.ParseMultipartForm(5 * 1024 * 1024)
    if err != nil {
        panic(err)
    }
   
    // Retrieve the file from the multipart form
    file, header, err := r.FormFile("fileupload")
    if err != nil {
        panic(err)
    }
    defer file.Close()
   
    // Do something with the uploaded file, such as storing it in a database or processing it
   }

3. To process the file, you can read its contents into a buffer and handle it as needed. Here's an example:

   var buf bytes.Buffer
    io.Copy(&buf, file)
    contents := buf.String()
    fmt.Println(contents)

4. If you are sending the file as multipart form data using cURL, make sure to provide the correct parameters:

   curl http://localhost:8080/upload -F "fileupload=[email protected]"

By following these steps, you can successfully receive uploaded files in your Golang net/http server using Mux.