gmail-api で添付ファイルを送りたい go言語

go

package main import ( "context" "encoding/base64" "encoding/json" "fmt" "io/ioutil" "log" "net/http" "os" "strings" "golang.org/x/oauth2" "golang.org/x/oauth2/google" "golang.org/x/text/encoding/japanese" "golang.org/x/text/transform" "google.golang.org/api/gmail/v1" "google.golang.org/api/option") func getClient(config *oauth2.Config) *http.Client { tokFile := "token.json" tok, err := tokenFromFile(tokFile) if err != nil { tok = getTokenFromWeb(config) saveToken(tokFile, tok) } return config.Client(context.Background(), tok)} 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 authCode string if _, err := fmt.Scan(&authCode); err != nil { log.Fatalf("Unable to read authorization code: %v", err) } tok, err := config.Exchange(context.TODO(), authCode) if err != nil { log.Fatalf("Unable to retrieve token from web: %v", err) } return tok } func tokenFromFile(file string) (*oauth2.Token, error) { f, err := os.Open(file) if err != nil { return nil, err } defer f.Close() tok := &oauth2.Token{} err = json.NewDecoder(f).Decode(tok) return tok, err } func saveToken(path string, token *oauth2.Token) { fmt.Printf("Saving credential file to: %s\n", path) f, err := os.OpenFile(path, 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 := os.ReadFile("credentials.json") if err != nil { log.Fatalf("Unable to read client secret file: %v", err) } config, err := google.ConfigFromJSON(b, gmail.MailGoogleComScope) if err != nil { log.Fatalf("Unable to parse client secret file to config: %v", err) } client := getClient(config) srv, err := gmail.NewService(ctx, option.WithHTTPClient(client)) if err != nil { log.Fatalf("Unable to retrieve Gmail client: %v", err) } fmt.Println("Created Gmail service", srv) //追記 msgStr := "From: 'me'\r\n" + "reply-to: gmail.com\r\n" + //送信元 "To: gmail.com\r\n" + //送信先 "Subject:test\r\n" + "\r\n" + "これはtestです" + "attach: Desktop/test.png" reader := strings.NewReader(msgStr) transformer := japanese.ISO2022JP.NewEncoder() msgISO2022JP, err := ioutil.ReadAll(transform.NewReader(reader, transformer)) if err != nil { log.Fatalf("Unable to convert to ISO2022JP: %v", err) } msg := []byte(msgISO2022JP) message := gmail.Message{} message.Raw = base64.StdEncoding.EncodeToString(msg) _, err = srv.Users.Messages.Send("me", &message).Do() if err != nil { fmt.Printf("%v", err) }}