So I wrote a SMTP log handler that has a
Write method, meaning it implements io.Writer, and can be used anywhere that requires io.Writer, e.g. log.new:func New(out io.Writer, prefix string, flag int) *LoggerSo that I can use:
logger := log.New(sw, "SMTPLOG: ", 0)
logger.Print("This is a test sent from SMTP Logger\n\nnemo")
sw is a SMTP log handler:type SMTPWriter struct {
auth smtp.Auth
user, pass, host, port string
sendto []string
subject string
}
func (w *SMTPWriter) Write(b []byte) (n int, err error) {
header := fmt.Sprintf(`Subject: %s
From: %s
To: %s
Content-Type: text/plain; charset=ISO-8859-1
`, w.subject, w.user, strings.Join(w.sendto, ";"))
err = smtp.SendMail(
w.host+":"+w.port,
w.auth,
w.user,
w.sendto,
append([]byte(header), b...),
)
if err != nil {
return 0, err
}
return len(b), nil
}
func NewSMTPWriter(user, pass, host, port string,
sendto []string, subject string) *SMTPWriter {
var auth = smtp.PlainAuth("", user, pass, host)
return &SMTPWriter{auth, user, pass, host, port, sendto, subject}
}
sw := NewSMTPWriter(
"test@jlee.co", // user
"test@jlee.co", // pass
"smtp.gmail.com", // server
"587", // port
[]string{"me@jlee.co", "jackie.space@gmai.com"}, // sendto
"Testing smtpwriter in a logger", // subject
)
And then like what you expect, you can use:logger.Print("This is a test sent from SMTP Logger\n\nnemo")
But it'll send a email on every call on logger's method. That's too verbose. I want to send a email when there is say 1024 chars.
Go has a bufio package. We can wrap our SMTPWriter using bufio:
func NewBufSMTPWriter(user, pass, host, port string,
sendto []string, subject string, bufsize int) (*bufio.Writer, error) {
sw := NewSMTPWriter(user, pass, host, port, sendto, subject)
w, err := bufio.NewWriterSize(sw, bufsize)
if err != nil {
return nil, err
}
return w, nil
}
See? you don't have to define a new
BufSMTPWriter, just return any struct that has a Write method, here I have a *buifio.Writer return type, you can even use io.Writer return type, because the target method call only cares if you have a Write method.the code is at https://github.com/jackielii/smtpwriter
