Implementing multipart file upload with extra params - go

Question

I am trying to replicate the following command:
curl -X POST --header 'Content-Type: multipart/form-data' --header 'Accept: text/html; charset=utf-8; profile="https://www.mediawiki.org/wiki/Specs/HTML/1.7.0"' -F wikitext=%27%27%27Mahikari%27%27%27%20is%20a%20%5B%5BJapan%5D%5Dese%20%5B%5Bnew%20religious%20movement%5D%5D -F body_only=true -F 'https://en.wikipedia.org/api/rest_v1/transform/wikitext/to/html'
The file is passed as a url quoted parameter to curl.
The content of the original file is given as (with no trailing returns):
'''Mahikari''' is a [[Japan]]ese [[new religious movement]]
The only parameter I added, for now, is body_only=true
The expected and correct answer is:
<p id="mwAQ"><b id="mwAg">Mahikari</b> is a <a rel="mw:WikiLink" href="./Japan" title="Japan" id="mwAw">Japanese</a> <a rel="mw:WikiLink" href="./New_religious_movement" title="New religious movement" id="mwBA">new religious movement</a></p>
The code below is not returning anything (not even an error!):
package main
import (
"bytes"
"fmt"
"io"
// "io/ioutil"
"log"
"mime/multipart"
"net/http"
"os"
"path/filepath"
)
// Creates a new file upload http request with optional extra params
func newfileUploadRequest(uri string, params map[string]string, paramName, path string) (*http.Request, error) {
file, err := os.Open(path)
if err != nil {
return nil, err
}
defer file.Close()
// fileContents, err := ioutil.ReadAll(file)
// if err != nil {
// return nil, err
// }
fi, err := file.Stat()
if err != nil {
return nil, err
}
body := new(bytes.Buffer)
writer := multipart.NewWriter(body)
part, err := writer.CreateFormFile(paramName, fi.Name())
if err != nil {
return nil, err
}
// part.Write(fileContents)
io.Copy(part, file)
for key, val := range params {
_ = writer.WriteField(key, val)
}
err = writer.Close()
if err != nil {
return nil, err
}
request, err := http.NewRequest("POST", uri, body)
request.Header.Add("Content-Type", writer.FormDataContentType())
request.Header.Add("Accept", "text/html; charset=utf-8; profile=\"https://www.mediawiki.org/wiki/Specs/HTML/1.7.0\"")
return request, err
}
func transformWikitextToHtml(path string) {
extraParams := map[string]string{
"body_only": "true",
}
request, err := newfileUploadRequest("https://en.wikipedia.org/api/rest_v1/transform/wikitext/to/html", extraParams, "file", path)
if err != nil {
log.Fatal(err)
}
client := &http.Client{}
resp, err := client.Do(request)
if err != nil {
log.Fatal(err)
} else {
var bodyContent []byte
fmt.Println(resp.StatusCode)
fmt.Println(resp.Header)
resp.Body.Read(bodyContent)
resp.Body.Close()
fmt.Println(bodyContent)
}
}
func main() {
transformWikitextToHtml("/tmp/2239217")
}
I set up the headers according to the documentation and what is expected. I tried a few things, as reading the file at once (commented out), but that didnt help. What am I missing?

Answer 1

In your CURL request, you are sending wikitext as a field (-F wikitext=...).
However, in your code you are sending it as a file part.
If you send that as a field it will work as you expect.
Just include the file contents as an additional extra field in your code:
func transformWikitextToHtml(path string) {
fileBytes, err := ioutil.ReadFile(path)
if err != nil {
log.Fatal(err)
}
extraParams := map[string]string{
"body_only": "true",
"wikitext": string(fileBytes),
}
// rest of the code should be as you posted
}
Then of course, remove the parts of newfileUploadRequest that work with the path and file param name, which are not needed any more.
Also, when writing the response body, you had a small bug and it was not printing anything even once the code was fixed, so please replace that part with:
bodyBytes, err := ioutil.ReadAll(resp.Body)
if err != nil {
log.Fatal(err)
}
fmt.Println(string(bodyBytes))
Full working code:
package main
import (
"bytes"
"fmt"
"log"
"mime/multipart"
"net/http"
"io/ioutil"
)
// Creates a new file upload http request with optional extra params
func newfileUploadRequest(uri string, params map[string]string) (*http.Request, error) {
body := new(bytes.Buffer)
writer := multipart.NewWriter(body)
for key, val := range params {
err := writer.WriteField(key, val)
if err != nil {
log.Fatal(err)
}
}
err := writer.Close()
if err != nil {
return nil, err
}
request, err := http.NewRequest("POST", uri, body)
request.Header.Add("Content-Type", writer.FormDataContentType())
request.Header.Add("Accept", "text/html; charset=utf-8; profile=\"https://www.mediawiki.org/wiki/Specs/HTML/1.7.0\"")
return request, err
}
func transformWikitextToHtml(path string) {
fileBytes, err := ioutil.ReadFile(path)
if err != nil {
log.Fatal(err)
}
extraParams := map[string]string{
"body_only": "true",
"wikitext": string(fileBytes),
}
request, err := newfileUploadRequest("https://en.wikipedia.org/api/rest_v1/transform/wikitext/to/html", extraParams)
if err != nil {
log.Fatal(err)
}
client := &http.Client{}
resp, err := client.Do(request)
if err != nil {
log.Fatal(err)
} else {
fmt.Println(resp.StatusCode)
fmt.Println(resp.Header)
bodyBytes, err := ioutil.ReadAll(resp.Body)
if err != nil {
log.Fatal(err)
}
fmt.Println(string(bodyBytes))
}
}
func main() {
transformWikitextToHtml("/tmp/2239217")
}