Can I post with Content-Type: multipart/form-data

user_8095085 0
Viewed 8633

How do I POST to an API with Content-Type: multipart/form-data, []byte parameters and string arguments? I have tried, but it is failing.

Error message:

details: "[301 301 Moved Permanently]<!DOCTYPE HTML PUBLIC \"-//IETF//DTD HTML 2.0//EN\">\r\n<html>\r\n301 Moved Permanently\r\n<body bgcolor=\"white\">\r\n301 Moved Permanently\r\n<p>The requested resource has been assigned a new permanent URI.</p >\r\n<hr/>Powered by Tengine/2.1.0</body>\r\n</html>\r\n"

Go code:

func NewPost2(url string) ([]byte, error) {
    m := make(map[string]interface{}, 0)
    m["fileName"] ="good"
    m["name"] = Base64ToByte("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")
b, _ := json.Marshal(m)

    httpReq, err := http.NewRequest("POST", url, bytes.NewBuffer(b))
    httpReq.Header.Set("Content-Type", "multipart/form-data;charset=UTF-8")

    client := &http.Client{}
    resp, err := client.Do(httpReq)
    if err != nil {
        return nil, err
    }

    defer resp.Body.Close()

    if resp.StatusCode < 200 || resp.StatusCode >= 300 {
        b, _ := ioutil.ReadAll(resp.Body)
        return nil, fmt.Errorf("[%d %s]%s", resp.StatusCode, resp.Status, string(b))
    }

    respData, err := ioutil.ReadAll(resp.Body)
    if err != nil {
        return nil, err
    }

    return respData, nil
}
go http
3 Answers

I wrapped the multipart code in a function, as you need to Close it before you can make a request. Also my method is using @ as a heuristic, similar to cURL [1]:

package main

import (
   "bytes"
   "io"
   "mime/multipart"
   "os"
   "strings"
)

func createForm(form map[string]string) (string, io.Reader, error) {
   body := new(bytes.Buffer)
   mp := multipart.NewWriter(body)
   defer mp.Close()
   for key, val := range form {
      if strings.HasPrefix(val, "@") {
         val = val[1:]
         file, err := os.Open(val)
         if err != nil { return "", nil, err }
         defer file.Close()
         part, err := mp.CreateFormFile(key, val)
         if err != nil { return "", nil, err }
         io.Copy(part, file)
      } else {
         mp.WriteField(key, val)
      }
   }
   return mp.FormDataContentType(), body, nil
}

Example:

package main
import "net/http"

func main() {
   form := map[string]string{"profile": "@portrait.jpg", "name": "John"}
   ct, body, err := createForm(form)
   if err != nil {
      panic(err)
   }
   http.Post("https://stackoverflow.com", ct, body)
}
  1. https://curl.se/docs/manpage.html#-F
user_10022600
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