Upload file through telegram bot to chat id

main.go

package main

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

func main() {
	token := "1111:asfasfa" //change token
	chatID := "111111" // change chat id

	method := "sendDocument"
	body := &bytes.Buffer{}
	writer := multipart.NewWriter(body)
	path := "/tmp/dat"
	file, err := os.Open(path)
	if err != nil {
		return
	}
	defer file.Close()
	part, err := writer.CreateFormFile("document", filepath.Base(path))
	if err != nil {
		return
	}

	if _, err = io.Copy(part, file); err != nil {
		return
	}

	writer.WriteField("chat_id", chatID)
	if err := writer.Close(); err != nil {
		return
	}
	url := fmt.Sprintf("https://api.telegram.org/bot%s/%s", token, method)
	req, err := http.NewRequest("POST", url, body)
	if err != nil {
		return
	}
	req.Header.Add("Content-Type", writer.FormDataContentType())
	client := &http.Client{}
	resp, err := client.Do(req)
	if err != nil {
		return
	}
	bodyBytes, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		fmt.Println(err)
	}
	bodyString := string(bodyBytes)
	fmt.Println(bodyString)
}