binding: add support of multipart multi files (#1878) (#1949)

* binding: add support of multipart multi files (#1878)

* update readme: add multipart file binding

binding/form.go

@@ -5,9 +5,7 @@
 package binding
 
 import (
-	"mime/multipart"
 	"net/http"
-	"reflect"
 )
 
 const defaultMemory = 32 * 1024 * 1024
@@ -63,27 +61,3 @@ func (formMultipartBinding) Bind(req *http.Request, obj interface{}) error {
 
 	return validate(obj)
 }
-
-type multipartRequest http.Request
-
-var _ setter = (*multipartRequest)(nil)
-
-var (
-	multipartFileHeaderStructType = reflect.TypeOf(multipart.FileHeader{})
-)
-
-// TrySet tries to set a value by the multipart request with the binding a form file
-func (r *multipartRequest) TrySet(value reflect.Value, field reflect.StructField, key string, opt setOptions) (isSetted bool, err error) {
-	if value.Type() == multipartFileHeaderStructType {
-		_, file, err := (*http.Request)(r).FormFile(key)
-		if err != nil {
-			return false, err
-		}
-		if file != nil {
-			value.Set(reflect.ValueOf(*file))
-			return true, nil
-		}
-	}
-
-	return setByForm(value, field, r.MultipartForm.Value, key, opt)
-}

binding/multipart_form_mapping.go

@@ -0,0 +1,66 @@
+// Copyright 2019 Gin Core Team.  All rights reserved.
+// Use of this source code is governed by a MIT style
+// license that can be found in the LICENSE file.
+
+package binding
+
+import (
+	"errors"
+	"mime/multipart"
+	"net/http"
+	"reflect"
+)
+
+type multipartRequest http.Request
+
+var _ setter = (*multipartRequest)(nil)
+
+// TrySet tries to set a value by the multipart request with the binding a form file
+func (r *multipartRequest) TrySet(value reflect.Value, field reflect.StructField, key string, opt setOptions) (isSetted bool, err error) {
+	if files := r.MultipartForm.File[key]; len(files) != 0 {
+		return setByMultipartFormFile(value, field, files)
+	}
+
+	return setByForm(value, field, r.MultipartForm.Value, key, opt)
+}
+
+func setByMultipartFormFile(value reflect.Value, field reflect.StructField, files []*multipart.FileHeader) (isSetted bool, err error) {
+	switch value.Kind() {
+	case reflect.Ptr:
+		switch value.Interface().(type) {
+		case *multipart.FileHeader:
+			value.Set(reflect.ValueOf(files[0]))
+			return true, nil
+		}
+	case reflect.Struct:
+		switch value.Interface().(type) {
+		case multipart.FileHeader:
+			value.Set(reflect.ValueOf(*files[0]))
+			return true, nil
+		}
+	case reflect.Slice:
+		slice := reflect.MakeSlice(value.Type(), len(files), len(files))
+		isSetted, err = setArrayOfMultipartFormFiles(slice, field, files)
+		if err != nil || !isSetted {
+			return isSetted, err
+		}
+		value.Set(slice)
+		return true, nil
+	case reflect.Array:
+		return setArrayOfMultipartFormFiles(value, field, files)
+	}
+	return false, errors.New("unsupported field type for multipart.FileHeader")
+}
+
+func setArrayOfMultipartFormFiles(value reflect.Value, field reflect.StructField, files []*multipart.FileHeader) (isSetted bool, err error) {
+	if value.Len() != len(files) {
+		return false, errors.New("unsupported len of array for []*multipart.FileHeader")
+	}
+	for i := range files {
+		setted, err := setByMultipartFormFile(value.Index(i), field, files[i:i+1])
+		if err != nil || !setted {
+			return setted, err
+		}
+	}
+	return true, nil
+}

binding/multipart_form_mapping_test.go

@@ -0,0 +1,138 @@
+// Copyright 2019 Gin Core Team.  All rights reserved.
+// Use of this source code is governed by a MIT style
+// license that can be found in the LICENSE file.
+
+package binding
+
+import (
+	"bytes"
+	"io/ioutil"
+	"mime/multipart"
+	"net/http"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestFormMultipartBindingBindOneFile(t *testing.T) {
+	var s struct {
+		FileValue   multipart.FileHeader     `form:"file"`
+		FilePtr     *multipart.FileHeader    `form:"file"`
+		SliceValues []multipart.FileHeader   `form:"file"`
+		SlicePtrs   []*multipart.FileHeader  `form:"file"`
+		ArrayValues [1]multipart.FileHeader  `form:"file"`
+		ArrayPtrs   [1]*multipart.FileHeader `form:"file"`
+	}
+	file := testFile{"file", "file1", []byte("hello")}
+
+	req := createRequestMultipartFiles(t, file)
+	err := FormMultipart.Bind(req, &s)
+	assert.NoError(t, err)
+
+	assertMultipartFileHeader(t, &s.FileValue, file)
+	assertMultipartFileHeader(t, s.FilePtr, file)
+	assert.Len(t, s.SliceValues, 1)
+	assertMultipartFileHeader(t, &s.SliceValues[0], file)
+	assert.Len(t, s.SlicePtrs, 1)
+	assertMultipartFileHeader(t, s.SlicePtrs[0], file)
+	assertMultipartFileHeader(t, &s.ArrayValues[0], file)
+	assertMultipartFileHeader(t, s.ArrayPtrs[0], file)
+}
+
+func TestFormMultipartBindingBindTwoFiles(t *testing.T) {
+	var s struct {
+		SliceValues []multipart.FileHeader   `form:"file"`
+		SlicePtrs   []*multipart.FileHeader  `form:"file"`
+		ArrayValues [2]multipart.FileHeader  `form:"file"`
+		ArrayPtrs   [2]*multipart.FileHeader `form:"file"`
+	}
+	files := []testFile{
+		{"file", "file1", []byte("hello")},
+		{"file", "file2", []byte("world")},
+	}
+
+	req := createRequestMultipartFiles(t, files...)
+	err := FormMultipart.Bind(req, &s)
+	assert.NoError(t, err)
+
+	assert.Len(t, s.SliceValues, len(files))
+	assert.Len(t, s.SlicePtrs, len(files))
+	assert.Len(t, s.ArrayValues, len(files))
+	assert.Len(t, s.ArrayPtrs, len(files))
+
+	for i, file := range files {
+		assertMultipartFileHeader(t, &s.SliceValues[i], file)
+		assertMultipartFileHeader(t, s.SlicePtrs[i], file)
+		assertMultipartFileHeader(t, &s.ArrayValues[i], file)
+		assertMultipartFileHeader(t, s.ArrayPtrs[i], file)
+	}
+}
+
+func TestFormMultipartBindingBindError(t *testing.T) {
+	files := []testFile{
+		{"file", "file1", []byte("hello")},
+		{"file", "file2", []byte("world")},
+	}
+
+	for _, tt := range []struct {
+		name string
+		s    interface{}
+	}{
+		{"wrong type", &struct {
+			Files int `form:"file"`
+		}{}},
+		{"wrong array size", &struct {
+			Files [1]*multipart.FileHeader `form:"file"`
+		}{}},
+		{"wrong slice type", &struct {
+			Files []int `form:"file"`
+		}{}},
+	} {
+		req := createRequestMultipartFiles(t, files...)
+		err := FormMultipart.Bind(req, tt.s)
+		assert.Error(t, err)
+	}
+}
+
+type testFile struct {
+	Fieldname string
+	Filename  string
+	Content   []byte
+}
+
+func createRequestMultipartFiles(t *testing.T, files ...testFile) *http.Request {
+	var body bytes.Buffer
+
+	mw := multipart.NewWriter(&body)
+	for _, file := range files {
+		fw, err := mw.CreateFormFile(file.Fieldname, file.Filename)
+		assert.NoError(t, err)
+
+		n, err := fw.Write(file.Content)
+		assert.NoError(t, err)
+		assert.Equal(t, len(file.Content), n)
+	}
+	err := mw.Close()
+	assert.NoError(t, err)
+
+	req, err := http.NewRequest("POST", "/", &body)
+	assert.NoError(t, err)
+
+	req.Header.Set("Content-Type", MIMEMultipartPOSTForm+"; boundary="+mw.Boundary())
+	return req
+}
+
+func assertMultipartFileHeader(t *testing.T, fh *multipart.FileHeader, file testFile) {
+	assert.Equal(t, file.Filename, fh.Filename)
+	// assert.Equal(t, int64(len(file.Content)), fh.Size) // fh.Size does not exist on go1.8
+
+	fl, err := fh.Open()
+	assert.NoError(t, err)
+
+	body, err := ioutil.ReadAll(fl)
+	assert.NoError(t, err)
+	assert.Equal(t, string(file.Content), string(body))
+
+	err = fl.Close()
+	assert.NoError(t, err)
+}