Custom data for multipart request

client.go

@@ -300,19 +300,20 @@ func (c *Client) SetAuthToken(token string) *Client {
 // R method creates a request instance, its used for Get, Post, Put, Delete, Patch, Head and Options.
 func (c *Client) R() *Request {
 	r := &Request{
-		URL:            "",
-		Method:         "",
-		QueryParam:     url.Values{},
-		FormData:       url.Values{},
-		Header:         http.Header{},
-		Body:           nil,
-		Result:         nil,
-		Error:          nil,
-		RawRequest:     nil,
-		client:         c,
-		bodyBuf:        nil,
-		multipartFiles: []*File{},
-		pathParams:     make(map[string]string),
+		URL:             "",
+		Method:          "",
+		QueryParam:      url.Values{},
+		FormData:        url.Values{},
+		Header:          http.Header{},
+		Body:            nil,
+		Result:          nil,
+		Error:           nil,
+		RawRequest:      nil,
+		client:          c,
+		bodyBuf:         nil,
+		multipartFiles:  []*File{},
+		multipartFields: []*multipartField{},
+		pathParams:      make(map[string]string),
 	}
 
 	return r
@@ -865,3 +866,11 @@ type File struct {
 func (f *File) String() string {
 	return fmt.Sprintf("ParamName: %v; FileName: %v", f.ParamName, f.Name)
 }
+
+// multipartField represent custom data part for multipart request
+type multipartField struct {
+	Param string
+	FileName string
+	ContentType string
+	io.Reader
+}

middleware.go

@@ -311,6 +311,15 @@ func handleMultipart(c *Client, r *Request) (err error) {
 		}
 	}
 
+	// GitHub #130 adding multipart field support with content type
+	if len(r.multipartFields) > 0 {
+		for _, mf := range r.multipartFields {
+			if err = addMultipartFormField(w, mf); err != nil {
+				return
+			}
+		}
+	}
+
 	r.Header.Set(hdrContentTypeKey, w.FormDataContentType())
 	err = w.Close()
 

request.go

@@ -281,6 +281,20 @@ func (r *Request) SetFileReader(param, fileName string, reader io.Reader) *Reque
 	return r
 }
 
+// SetMultipartField method is to set custom data using io.Reader for multipart upload.
+func (r *Request) SetMultipartField(param, fileName, contentType string, reader io.Reader) *Request {
+	r.isMultiPart = true
+
+	r.multipartFields = append(r.multipartFields, &multipartField{
+		Param:       param,
+		FileName:    fileName,
+		ContentType: contentType,
+		Reader:      reader,
+	})
+
+	return r
+}
+
 // SetContentLength method sets the HTTP header `Content-Length` value for current request.
 // By default go-resty won't set `Content-Length`. Also you have an option to enable for every
 // request. See `resty.SetContentLength`

request16.go

@@ -43,6 +43,7 @@ type Request struct {
 	isSaveResponse      bool
 	outputFile          string
 	multipartFiles      []*File
+	multipartFields     []*multipartField
 	notParseResponse    bool
 	fallbackContentType string
 	pathParams          map[string]string

request17.go

@@ -44,6 +44,7 @@ type Request struct {
 	isSaveResponse      bool
 	outputFile          string
 	multipartFiles      []*File
+	multipartFields     []*multipartField
 	notParseResponse    bool
 	ctx                 context.Context
 	fallbackContentType string

request_test.go

@@ -613,6 +613,25 @@ func TestMultiPartUploadFileNotOnGetOrDelete(t *testing.T) {
 	assertEqual(t, "multipart content is not allowed in HTTP verb [DELETE]", err.Error())
 }
 
+func TestMultiPartMultipartField(t *testing.T) {
+	ts := createFormPostServer(t)
+	defer ts.Close()
+	defer cleanupFiles("test-data/upload")
+
+	jsonBytes := []byte(`{"input": {"name": "Uploaded document", "_filename" : ["file.txt"]}}`)
+
+	resp, err := dclr().
+		SetFormData(map[string]string{"first_name": "Jeevanandam", "last_name": "M"}).
+		SetMultipartField("uploadManifest", "upload-file.json", "application/json", bytes.NewReader(jsonBytes)).
+		Post(ts.URL + "/upload")
+
+	responseStr := resp.String()
+
+	assertError(t, err)
+	assertEqual(t, http.StatusOK, resp.StatusCode())
+	assertEqual(t, true, strings.Contains(responseStr, "upload-file.json"))
+}
+
 func TestGetWithCookie(t *testing.T) {
 	ts := createGetServer(t)
 	defer ts.Close()

util.go

@@ -107,6 +107,24 @@ func escapeQuotes(s string) string {
 	return quoteEscaper.Replace(s)
 }
 
+func createMultipartHeader(param, fileName, contentType string) textproto.MIMEHeader {
+	hdr := make(textproto.MIMEHeader)
+	hdr.Set("Content-Disposition", fmt.Sprintf(`form-data; name="%s"; filename="%s"`,
+		escapeQuotes(param), escapeQuotes(fileName)))
+	hdr.Set("Content-Type", contentType)
+	return hdr
+}
+
+func addMultipartFormField(w *multipart.Writer, mf *multipartField) error {
+	partWriter, err := w.CreatePart(createMultipartHeader(mf.Param, mf.FileName, mf.ContentType))
+	if err != nil {
+		return err
+	}
+
+	_, err = io.Copy(partWriter, mf.Reader)
+	return err
+}
+
 func writeMultipartFormFile(w *multipart.Writer, fieldName, fileName string, r io.Reader) error {
 	// Auto detect actual multipart content type
 	cbuf := make([]byte, 512)
@@ -115,11 +133,7 @@ func writeMultipartFormFile(w *multipart.Writer, fieldName, fileName string, r i
 		return err
 	}
 
-	h := make(textproto.MIMEHeader)
-	h.Set("Content-Disposition", fmt.Sprintf(`form-data; name="%s"; filename="%s"`,
-		escapeQuotes(fieldName), escapeQuotes(fileName)))
-	h.Set("Content-Type", http.DetectContentType(cbuf))
-	partWriter, err := w.CreatePart(h)
+	partWriter, err := w.CreatePart(createMultipartHeader(fieldName, fileName, http.DetectContentType(cbuf)))
 	if err != nil {
 		return err
 	}