The third parameter of http.Post()
allows io.Reader
and that means the return value of os.Open()
should work. But the below code gets unexpected result, in other words, it won't set Content-Length
properly. Perhaps File
type doesn't implement something. Is there any proper way to set Content-Length
with *File
?
package main
import (
"bytes"
"io/ioutil"
"log"
"net/http"
"net/http/httptest"
"os"
)
var sample = []byte(`hello`)
func main() {
ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
log.Println(r.Header)
if int(r.ContentLength) != len(sample) {
log.Fatal("Unexpected Content-Length:", r.ContentLength)
}
w.Header().Set("Content-Type", "application/json")
w.Write([]byte(`{}`))
}))
defer ts.Close()
file, err := ioutil.TempFile(os.TempDir(), "")
if err != nil {
log.Fatal(err)
}
defer os.Remove(file.Name())
file.Write(sample)
// This works
buf, err := ioutil.ReadFile(file.Name())
if err != nil {
log.Fatal(err)
}
_, err = http.Post(ts.URL, "application/octet-stream", bytes.NewBuffer(buf))
if err != nil {
log.Fatal(err)
}
// This looks fine in my opinion, though it doesn't set Content-Length
f, err := os.Open(file.Name())
if err != nil {
log.Fatal(err)
}
_, err = http.Post(ts.URL, "application/octet-stream", f)
if err != nil {
log.Fatal(err)
}
}
Output:
2009/11/10 23:00:00 map[Content-Type:[application/octet-stream] Accept-Encoding:[gzip] User-Agent:[Go-http-client/1.1] Content-Length:[5]]
2009/11/10 23:00:00 map[Content-Type:[application/octet-stream] Accept-Encoding:[gzip] User-Agent:[Go-http-client/1.1]]
2009/11/10 23:00:00 Unexpected Content-Length:-1