gmail batch request

batch.go

/*
 Author: Sergio Schvezov

 Calling this will dump a response similar to:

 HTTP/1.1 200 OK
 Transfer-Encoding: chunked
 Alternate-Protocol: 443:quic
 Cache-Control: no-cache, no-store, max-age=0, must-revalidate
 Content-Type: multipart/mixed; boundary=batch_mtD6I8ONpCM=_AAPHSI2gDBg=
 Date: Fri, 15 Aug 2014 13:06:49 GMT
 Expires: Fri, 01 Jan 1990 00:00:00 GMT
 Pragma: no-cache
 Server: GSE
 X-Content-Type-Options: nosniff
 X-Frame-Options: SAMEORIGIN
 X-Xss-Protection: 1; mode=block

 1df0
 --batch_mtD6I8ONpCM=_AAPHSI2gDBg=
 Content-Type: application/http

 HTTP/1.1 200 OK
 ETag: "QLs4pSnnOYcKsc2Nteng63h1s-w/R0OLs2HgEc9fXAJB-Z33SOeIrJk"
 Content-Type: application/json; charset=UTF-8
 Date: Fri, 15 Aug 2014 13:06:49 GMT
 Expires: Fri, 15 Aug 2014 13:06:49 GMT
 Cache-Control: private, max-age=0
 Content-Length: 7291

 {
      "messages": [
      {
        "id": "XXXXXX",
        "threadId": "XXXXXXXX"
      },
 ...
 ...
 ...
  ],
  "nextPageToken": "12798809368304798032",
  "resultSizeEstimate": 624
 }

 --batch_mtD6I8ONpCM=_AAPHSI2gDBg=--

   0

*/

package main

import (
	"bytes"
	"fmt"
	"mime/multipart"
	"net/http"
	"net/http/httputil"
	"net/textproto"
	"os"
)

func main() {
	if len(os.Args) < 2 {
		fmt.Println("usage:", os.Args[0], "[access_token]")
		return
	}

	accessToken := os.Args[1]

	buffer := new(bytes.Buffer)
	multipartW := multipart.NewWriter(buffer)

	mh := make(textproto.MIMEHeader)
	mh.Set("Content-Type", "application/http")
	// mh.Set("Content-Id", "list")

	partW, err := multipartW.CreatePart(mh)
	if err != nil {
		fmt.Println("cannot create part:", err)
		return
	}
	content := []byte("GET https://www.googleapis.com/gmail/v1/users/me/messages HTTP/1.1\r\n")
	partW.Write(content)
	multipartW.Close()

	req, err := http.NewRequest("POST", "https://www.googleapis.com/batch", buffer)
	if err != nil {
		fmt.Println("cannot create batch request:", err)
		return
	}
	req.Header.Set("Authorization", "Bearer "+accessToken)
	req.Header.Set("Content-Type", "multipart/mixed; boundary="+multipartW.Boundary())

	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		fmt.Println("error while requesting batch:", err)
		return
	}

	respDump, err := httputil.DumpResponse(resp, true)
	if err != nil {
		fmt.Println("failed to dump response:", err)
		return
	}
	fmt.Println(string(respDump))

}