Use google api using Oauth

oauth-for-google-api.go

package main

import (
	"encoding/json"
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
	"net/url"
	"os"
	"os/user"
	"path/filepath"

	"golang.org/x/net/context"
	"golang.org/x/oauth2"
	"golang.org/x/oauth2/google"
	"google.golang.org/api/drive/v3"
	"google.golang.org/api/sheets/v4"
)

// getClient uses a Context and Config to retrieve a Token
// then generate a Client. It returns the generated Client.
func getClient(ctx context.Context, config *oauth2.Config) *http.Client {
	cacheFile, err := tokenCacheFile()
	if err != nil {
		log.Fatalf("Unable to get path to cached credential file. %v", err)
	}
	tok, err := tokenFromFile(cacheFile)
	if err != nil {
		tok = getTokenFromWeb(config)
		saveToken(cacheFile, tok)
	}
	return config.Client(ctx, tok)
}

// getTokenFromWeb uses Config to request a Token.
// It returns the retrieved Token.
func getTokenFromWeb(config *oauth2.Config) *oauth2.Token {
	authURL := config.AuthCodeURL("state-token", oauth2.AccessTypeOffline)
	fmt.Printf("Go to the following link in your browser then type the "+
		"authorization code: \n%v\n", authURL)

	var code string
	if _, err := fmt.Scan(&code); err != nil {
		log.Fatalf("Unable to read authorization code %v", err)
	}

	tok, err := config.Exchange(oauth2.NoContext, code)
	if err != nil {
		log.Fatalf("Unable to retrieve token from web %v", err)
	}
	return tok
}

// tokenCacheFile generates credential file path/filename.
// It returns the generated credential path/filename.
func tokenCacheFile() (string, error) {
	usr, err := user.Current()
	if err != nil {
		return "", err
	}
	tokenCacheDir := filepath.Join(usr.HomeDir, ".credentials")
	os.MkdirAll(tokenCacheDir, 0700)
	return filepath.Join(tokenCacheDir,
		url.QueryEscape("drive-go-quickstart.json")), err
}

// tokenFromFile retrieves a Token from a given file path.
// It returns the retrieved Token and any read error encountered.
func tokenFromFile(file string) (*oauth2.Token, error) {
	f, err := os.Open(file)
	if err != nil {
		return nil, err
	}
	t := &oauth2.Token{}
	err = json.NewDecoder(f).Decode(t)
	defer f.Close()
	return t, err
}

// saveToken uses a file path to create a file and store the
// token in it.
func saveToken(file string, token *oauth2.Token) {
	fmt.Printf("Saving credential file to: %s\n", file)
	f, err := os.OpenFile(file, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0600)
	if err != nil {
		log.Fatalf("Unable to cache oauth token: %v", err)
	}
	defer f.Close()
	json.NewEncoder(f).Encode(token)
}

func main() {
	ctx := context.Background()

	b, err := ioutil.ReadFile("client_id.json")
	if err != nil {
		log.Fatalf("Unable to read client secret file: %v", err)
	}

	// If modifying these scopes, delete your previously saved credentials
	// at ~/.credentials/drive-go-quickstart.json
	config, err := google.ConfigFromJSON(b, drive.DriveFileScope, sheets.DriveFileScope)
	if err != nil {
		log.Fatalf("Unable to parse client secret file to config: %v", err)
	}
	client := getClient(ctx, config)

	srv, err := drive.New(client)
	if err != nil {
		log.Fatalf("Unable to retrieve drive Client %v", err)
	}

	r, err := srv.Files.List().PageSize(10).
		Fields("nextPageToken, files(id, name)").Do()
	if err != nil {
		log.Fatalf("Unable to retrieve files: %v", err)
	}

	fmt.Println("Files:")
	if len(r.Files) > 0 {
		for _, i := range r.Files {
			fmt.Printf("%s (%s)\n", i.Name, i.Id)
		}
	} else {
		fmt.Println("No files found.")
	}

	shtsrv, _ := sheets.New(client)
	sprsheet := &sheets.Spreadsheet{
		Properties: &sheets.SpreadsheetProperties{
			Title: "Hello SHeets",
		},
		Sheets: []*sheets.Sheet{
			{Data: []*sheets.GridData{
				{RowData: []*sheets.RowData{
					{Values: []*sheets.CellData{
					}},
				},},
			},},
		},
	}

	mysheet, _ := shtsrv.Spreadsheets.Create(sprsheet).Do()
	readRange := "A1:A5"
	data := [][]interface{}{
		{"string"},{"wtp"},{"three"},{"three"},{"three"},
	}
	myvalues := &sheets.ValueRange{
		Values: data,
	}

	resp,err := shtsrv.Spreadsheets.Values.Update(mysheet.SpreadsheetId, readRange, myvalues).ValueInputOption("RAW").Context(context.Background()).Do()
	fmt.Println(resp)
	if err!=nil{
		fmt.Println(err.Error())
	}

}