From 99bf8e8630234da4b4a05442b76683df7dd4dd32 Mon Sep 17 00:00:00 2001
From: Karl Haas <karl.haas@coditects.com>
Date: Wed, 2 Aug 2023 14:08:51 +0000
Subject: [PATCH] feature: Support the upload of multiple files

---
 binding/file_request_type_binder.go | 29 ++++++++----
 binding/file_test.go                | 68 +++++++++++++++++++++--------
 2 files changed, 71 insertions(+), 26 deletions(-)

diff --git a/binding/file_request_type_binder.go b/binding/file_request_type_binder.go
index 0d99c9e7b..570f9ba73 100644
--- a/binding/file_request_type_binder.go
+++ b/binding/file_request_type_binder.go
@@ -52,17 +52,30 @@ func (ht FileRequestTypeBinder) BinderFunc() Binder {
 			if !f.IsValid() {
 				continue
 			}
-			if _, ok := f.Interface().(File); !ok {
+			if f.Kind() == reflect.Slice {
+				for _, fh := range req.MultipartForm.File[n] {
+					mf, err := fh.Open()
+					if err != nil {
+						return err
+					}
+
+					f.Set(reflect.Append(f, reflect.ValueOf(File{
+						File:       mf,
+						FileHeader: fh,
+					})))
+				}
 				continue
 			}
-			mf, mh, err := req.FormFile(n)
-			if err != nil {
-				return err
+			if _, ok := f.Interface().(File); ok {
+				mf, mh, err := req.FormFile(n)
+				if err != nil {
+					return err
+				}
+				f.Set(reflect.ValueOf(File{
+					File:       mf,
+					FileHeader: mh,
+				}))
 			}
-			f.Set(reflect.ValueOf(File{
-				File:       mf,
-				FileHeader: mh,
-			}))
 		}
 
 		return nil
diff --git a/binding/file_test.go b/binding/file_test.go
index ca66a5294..4ed01792f 100644
--- a/binding/file_test.go
+++ b/binding/file_test.go
@@ -2,12 +2,14 @@ package binding_test
 
 import (
 	"bytes"
+	"fmt"
 	"io"
 	"mime/multipart"
 	"net/http"
 	"net/http/httptest"
 	"os"
 	"path/filepath"
+	"strings"
 	"testing"
 
 	"github.com/gobuffalo/buffalo"
@@ -20,6 +22,10 @@ type WithFile struct {
 	MyFile binding.File
 }
 
+type NamedFileSlice struct {
+	MyFiles []binding.File `form:"thefiles"`
+}
+
 type NamedFile struct {
 	MyFile binding.File `form:"afile"`
 }
@@ -40,6 +46,18 @@ func App() *buffalo.App {
 		}
 		return c.Render(http.StatusCreated, render.String(wf.MyFile.Filename))
 	})
+	a.POST("/named-file-slice", func(c buffalo.Context) error {
+		wmf := &NamedFileSlice{}
+		if err := c.Bind(wmf); err != nil {
+			return err
+		}
+		result := make([]string, len(wmf.MyFiles))
+		for i, f := range wmf.MyFiles {
+			result[i] += fmt.Sprintf("%s:%d", f.Filename, f.Size)
+
+		}
+		return c.Render(http.StatusCreated, render.String(strings.Join(result, ",")))
+	})
 	a.POST("/on-context", func(c buffalo.Context) error {
 		f, err := c.File("MyFile")
 		if err != nil {
@@ -54,7 +72,7 @@ func App() *buffalo.App {
 func Test_File_Upload_On_Struct(t *testing.T) {
 	r := require.New(t)
 
-	req, err := newfileUploadRequest("/on-struct", "MyFile", "file_test.go")
+	req, err := newFileUploadRequest("/on-struct", "MyFile", "file_test.go")
 	r.NoError(err)
 	res := httptest.NewRecorder()
 
@@ -64,10 +82,23 @@ func Test_File_Upload_On_Struct(t *testing.T) {
 	r.Equal("file_test.go", res.Body.String())
 }
 
+func Test_File_Upload_On_Struct_WithTag_WithMultipleFiles(t *testing.T) {
+	r := require.New(t)
+
+	req, err := newFileUploadRequest("/named-file-slice", "thefiles", "file_test.go", "file.go", "types.go")
+	r.NoError(err)
+	res := httptest.NewRecorder()
+
+	App().ServeHTTP(res, req)
+
+	r.Equal(http.StatusCreated, res.Code)
+	r.Equal("file_test.go:3672,file.go:348,types.go:507", res.Body.String())
+}
+
 func Test_File_Upload_On_Struct_WithTag(t *testing.T) {
 	r := require.New(t)
 
-	req, err := newfileUploadRequest("/named-file", "afile", "file_test.go")
+	req, err := newFileUploadRequest("/named-file", "afile", "file_test.go")
 	r.NoError(err)
 	res := httptest.NewRecorder()
 
@@ -80,7 +111,7 @@ func Test_File_Upload_On_Struct_WithTag(t *testing.T) {
 func Test_File_Upload_On_Context(t *testing.T) {
 	r := require.New(t)
 
-	req, err := newfileUploadRequest("/on-context", "MyFile", "file_test.go")
+	req, err := newFileUploadRequest("/on-context", "MyFile", "file_test.go")
 	r.NoError(err)
 	res := httptest.NewRecorder()
 
@@ -92,27 +123,28 @@ func Test_File_Upload_On_Context(t *testing.T) {
 
 // this helper method was inspired by this blog post by Matt Aimonetti:
 // https://matt.aimonetti.net/posts/2013/07/01/golang-multipart-file-upload-example/
-func newfileUploadRequest(uri string, paramName, path string) (*http.Request, error) {
-	file, err := os.Open(path)
-	if err != nil {
-		return nil, err
-	}
-	defer file.Close()
-
+func newFileUploadRequest(uri string, paramName string, paths ...string) (*http.Request, error) {
 	body := &bytes.Buffer{}
 	writer := multipart.NewWriter(body)
-	part, err := writer.CreateFormFile(paramName, filepath.Base(path))
-	if err != nil {
-		return nil, err
-	}
-	if _, err = io.Copy(part, file); err != nil {
-		return nil, err
+
+	for _, path := range paths {
+		file, err := os.Open(path)
+		if err != nil {
+			return nil, err
+		}
+		defer file.Close()
+		part, err := writer.CreateFormFile(paramName, filepath.Base(path))
+		if err != nil {
+			return nil, err
+		}
+		if _, err = io.Copy(part, file); err != nil {
+			return nil, err
+		}
 	}
 
-	if err = writer.Close(); err != nil {
+	if err := writer.Close(); err != nil {
 		return nil, err
 	}
-
 	req, err := http.NewRequest("POST", uri, body)
 	req.Header.Set("Content-Type", writer.FormDataContentType())
 	return req, err