Resumable Uploading Files to Google Drive using Golang

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Resumable Uploading Files to Google Drive using Golang

This is a sample script for the resumable upload of Files to Google Drive using Golang. This script uses the library of google-api-go-client. About the installation of google-api-go-client, please check the Quickstart for golang at the official site.

Sample script:

package main

import (
	"context"
	"encoding/json"
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
	"os"

	drive "google.golang.org/api/drive/v3"

	"golang.org/x/oauth2"
	"golang.org/x/oauth2/google"
	"golang.org/x/oauth2/jwt"
)

// ServiceAccount : Use Service account
func ServiceAccount(credentialFile string) *http.Client {
	b, err := ioutil.ReadFile(credentialFile)
	if err != nil {
		log.Fatal(err)
	}
	var c = struct {
		Email      string `json:"client_email"`
		PrivateKey string `json:"private_key"`
	}{}
	json.Unmarshal(b, &c)
	config := &jwt.Config{
		Email:      c.Email,
		PrivateKey: []byte(c.PrivateKey),
		Scopes: []string{
			drive.DriveScope,
		},
		TokenURL: google.JWTTokenURL,
	}
	client := config.Client(oauth2.NoContext)
	return client
}

func main() {
	filename := "sample.txt"     // Filename
	baseMimeType := "text/plain" // MimeType
	client := ServiceAccount("credential.json") // Please set the json file of Service account.

	srv, err := drive.New(client)
	if err != nil {
		log.Fatalln(err)
	}
	file, err := os.Open(filename)
	if err != nil {
		log.Fatalln(err)
	}
	fileInf, err := file.Stat()
	if err != nil {
		log.Fatalln(err)
	}
	defer file.Close()
	f := &drive.File{Name: filename}
	res, err := srv.Files.
		Create(f).
		ResumableMedia(context.Background(), file, fileInf.Size(), baseMimeType).
		ProgressUpdater(func(now, size int64) { fmt.Printf("%d, %d\r", now, size) }).
		Do()
	if err != nil {
		log.Fatalln(err)
	}
	fmt.Printf("%s\n", res.Id)
}

Note:

• In this sample, the Service account is used. So the file is uploaded to the Service account's Drive. When client retrieved from OAuth2 is used, the file is uploaded to owner's Drive.

References:

• google-api-go-client
• package drive