golang file upload

fileupload.go

package main

import (
	"bytes"
	"fmt"
	"io/ioutil"
	"mime/multipart"
	"net/http"
)

func main() {
	var guidEmpty = "00000000-0000-0000-0000-000000000000"
	uri := "http://localhost:8080/file/" + guidEmpty

	pars := map[string]string{
		"meta": "test",
	}

	req, _ := newfileUploadRequest(uri, pars, "upload", "mmm.txt", []byte("mmmm"))
	client := http.Client{}
	resp, _ := client.Do(req)
	raw, _ := ioutil.ReadAll(resp.Body)
	fmt.Println(string(raw))
}

func newfileUploadRequest(uri string, params map[string]string, paramName string, fName string,
	fileContents []byte) (*http.Request, error) {

	body := new(bytes.Buffer)
	writer := multipart.NewWriter(body)
	part, err := writer.CreateFormFile(paramName, fName)
	if err != nil {
		return nil, err
	}
	part.Write(fileContents)

	for key, val := range params {
		_ = writer.WriteField(key, val)
	}
	err = writer.Close()
	if err != nil {
		return nil, err
	}

	req, _ := http.NewRequest("POST", uri, body)
	req.Header.Set("Content-Type", writer.FormDataContentType())
	return req, err
}