Attaching image to email sent through golang gmail api - go

Question

I'm trying to attach a picture to an email sent through the gmail golang api, but the image does not attach. I've looked extensively at the documentation, but I have not been able to figure out how to attach an image to an email. Here is the code that I have so far. It only sends the text.
// SendEmailEmbed2 Sends email through gmail
func (config *GmailConfig) SendEmailEmbed2(person int, formattedTemplate string) {
msg := formattedTemplate
mmbody := gmail.MessagePartBody{
Data: encodeWeb64String([]byte(msg)),
}
headers := []*gmail.MessagePartHeader{
&gmail.MessagePartHeader{
Name: "From",
Value: config.FromAddress,
},
&gmail.MessagePartHeader{
Name: "To",
Value: config.CSVReference.Elem(person, config.PlugIns[0].ToEmail).String(),
},
&gmail.MessagePartHeader{
Name: "Subject",
Value: config.EmailSubject,
},
&gmail.MessagePartHeader{
Name: "Content-Disposition",
Value: "./prac2_files/image001.jpg",
},
}
Parts := []*gmail.MessagePart{
&gmail.MessagePart{
Filename: "./prac2_files/image001.jpg",
},
}
partgmsg := gmail.MessagePart{
Body: &mmbody,
Headers: headers,
Parts: Parts,
MimeType: "multipart",
}
im, _ := os.Open("./prac2_files/image001.jpg")
gmsg := gmail.Message{
Payload: &partgmsg,
Raw: encodeWeb64String([]byte(msg)),
}
call, err := config.srv.Users.Messages.Send("me", &gmsg).Media(im).Do()
im.Close()
if err != nil {
log.Println("em %v, err %v", gmsg, err)
// return err
}
// return err
fmt.Println(person, ":", headers[1].Value, " : ", call.LabelIds)
}
func encodeWeb64String(b []byte) string {
s := base64.URLEncoding.EncodeToString(b)
var i = len(s) - 1
for s[i] == '=' {
i--
}
return s[0 : i+1]
}

Answer 1

Answer:
You need to attach the file inline in the body of the message.
Code:
message := gmail.Message
attachmentBytes := ioutil.ReadFile(fileDir + fileName)
attachmentMimeType: = http.DetectContentType(attachmentBytes)
attachmentData: = base64.StdEncoding.EncodeToString(attachmentBytes)
boundary: = randStr(32, "alphanum")
messageBody: = [] byte("Content-Type: multipart/mixed; boundary=" + boundary + " \n" +
"MIME-Version: 1.0\n" +
"to: " + config.CSVReference.Elem(person, config.PlugIns[0].ToEmail).String() + "\n" +
"from: " + config.FromAddress + "\n" +
"subject: " + config.EmailSubject + "\n\n" +
"--" + boundary + "\n" +
"Content-Type: text/plain; charset=" + string('"') + "UTF-8" + string('"') + "\n" +
"MIME-Version: 1.0\n" +
"Content-Transfer-Encoding: 7bit\n\n" +
content + "\n\n" +
"--" + boundary + "\n" +
"Content-Type: " + "image/jpg" + "; name=" + string('"') + fileName + string('"') + " \n" +
"MIME-Version: 1.0\n" +
"Content-Transfer-Encoding: base64\n" +
"Content-Disposition: attachment; filename=" + string('"') + fileName + string('"') + " \n\n" +
chunkSplit(attachmentData, 76, "\n") +
"--" + boundary + "--")
message.Raw = base64.URLEncoding.EncodeToString(messageBody)
_, err := service.Users.Messages.Send("me", &message).Do()
if err != nil {
log.Fatalf("Email sending failed: %v", err)
} else {
log.Println("Email message sent")
}