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package message_test
import (
"bytes"
"io"
"log"
"strings"
"github.com/emersion/go-message"
)
func ExampleRead() {
// Let's assume r is an io.Reader that contains a message.
var r io.Reader
m, err := message.Read(r)
if message.IsUnknownCharset(err) {
// This error is not fatal
log.Println("Unknown encoding:", err)
} else if err != nil {
log.Fatal(err)
}
if mr := m.MultipartReader(); mr != nil {
// This is a multipart message
log.Println("This is a multipart message containing:")
for {
p, err := mr.NextPart()
if err == io.EOF {
break
} else if err != nil {
log.Fatal(err)
}
t, _, _ := p.Header.ContentType()
log.Println("A part with type", t)
}
} else {
t, _, _ := m.Header.ContentType()
log.Println("This is a non-multipart message with type", t)
}
}
func ExampleWriter() {
var b bytes.Buffer
var h message.Header
h.SetContentType("multipart/alternative", nil)
w, err := message.CreateWriter(&b, h)
if err != nil {
log.Fatal(err)
}
var h1 message.Header
h1.SetContentType("text/html", nil)
w1, err := w.CreatePart(h1)
if err != nil {
log.Fatal(err)
}
io.WriteString(w1, "<h1>Hello World!</h1><p>This is an HTML part.</p>")
w1.Close()
var h2 message.Header
h2.SetContentType("text/plain", nil)
w2, err := w.CreatePart(h2)
if err != nil {
log.Fatal(err)
}
io.WriteString(w2, "Hello World!\n\nThis is a text part.")
w2.Close()
w.Close()
log.Println(b.String())
}
func Example_transform() {
// Let's assume r is an io.Reader that contains a message.
var r io.Reader
m, err := message.Read(r)
if message.IsUnknownCharset(err) {
log.Println("Unknown encoding:", err)
} else if err != nil {
log.Fatal(err)
}
// We'll add "This message is powered by Go" at the end of each text entity.
poweredBy := "\n\nThis message is powered by Go."
var b bytes.Buffer
w, err := message.CreateWriter(&b, m.Header)
if err != nil {
log.Fatal(err)
}
// Define a function that transforms message.
var transform func(w *message.Writer, e *message.Entity) error
transform = func(w *message.Writer, e *message.Entity) error {
if mr := e.MultipartReader(); mr != nil {
// This is a multipart entity, transform each of its parts
for {
p, err := mr.NextPart()
if err == io.EOF {
break
} else if err != nil {
return err
}
pw, err := w.CreatePart(p.Header)
if err != nil {
return err
}
if err := transform(pw, p); err != nil {
return err
}
pw.Close()
}
return nil
} else {
body := e.Body
if strings.HasPrefix(m.Header.Get("Content-Type"), "text/") {
body = io.MultiReader(body, strings.NewReader(poweredBy))
}
_, err := io.Copy(w, body)
return err
}
}
if err := transform(w, m); err != nil {
log.Fatal(err)
}
w.Close()
log.Println(b.String())
}
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