lib/http: export function to generate "multipart/form-data"

The GenerateFormData generate the request body with boundary for
HTTP content-type "multipart/form-data" from map[string][]byte.

3 files changed, 65 insertions, 8 deletions

diff --git a/lib/http/client.go b/lib/http/client.go
index 05368092..cdfb1979 100644
--- a/lib/http/client.go
+++ b/lib/http/client.go
@@ -21,6 +21,7 @@ import (
 	"net/http"
 	"net/url"
 	"path"
+	"sort"
 	"strings"
 	"time"
 
@@ -243,7 +244,7 @@ func (client *Client) GenerateHttpRequest(
 		case RequestTypeMultipartForm:
 			paramsAsMultipart, ok := params.(map[string][]byte)
 			if ok {
-				contentType, strBody, err = generateFormData(paramsAsMultipart)
+				contentType, strBody, err = GenerateFormData(paramsAsMultipart)
 				if err != nil {
 					return nil, fmt.Errorf("%s: %w", logp, err)
 				}
@@ -336,7 +337,7 @@ func (client *Client) PostFormData(
 ) (
 	res *http.Response, resBody []byte, err error,
 ) {
-	contentType, strBody, err := generateFormData(params)
+	contentType, strBody, err := GenerateFormData(params)
 	if err != nil {
 		return nil, nil, fmt.Errorf("http: PostFormData: %w", err)
 	}
@@ -393,7 +394,7 @@ func (client *Client) PutFormData(rpath string, hdr http.Header, params map[stri
 		body        *strings.Reader
 	)
 
-	contentType, strBody, err = generateFormData(params)
+	contentType, strBody, err = GenerateFormData(params)
 	if err != nil {
 		return nil, nil, fmt.Errorf(`http: PutFormData: %w`, err)
 	}
@@ -540,21 +541,30 @@ func (client *Client) uncompress(res *http.Response, body []byte) (
 	return out, err
 }
 
-// generateFormData generate multipart/form-data body from params.
-func generateFormData(params map[string][]byte) (contentType, body string, err error) {
+// GenerateFormData generate multipart/form-data body from params.
+func GenerateFormData(params map[string][]byte) (contentType, body string, err error) {
 	var (
 		sb = new(strings.Builder)
 		w  = multipart.NewWriter(sb)
 
+		k       string
+		listKey []string
+	)
+	for k = range params {
+		listKey = append(listKey, k)
+	}
+	sort.Strings(listKey)
+
+	var (
 		part io.Writer
-		k    string
 		v    []byte
 	)
-	for k, v = range params {
+	for _, k = range listKey {
 		part, err = w.CreateFormField(k)
 		if err != nil {
 			return "", "", err
 		}
+		v = params[k]
 		_, err = part.Write(v)
 		if err != nil {
 			return "", "", err
diff --git a/lib/http/client_example_test.go b/lib/http/client_example_test.go
new file mode 100644
index 00000000..2d7d3bdf
--- /dev/null
+++ b/lib/http/client_example_test.go
@@ -0,0 +1,47 @@
+package http_test
+
+import (
+	"crypto/rand"
+	"fmt"
+	"log"
+	"strings"
+
+	libhttp "github.com/shuLhan/share/lib/http"
+	"github.com/shuLhan/share/lib/test/mock"
+)
+
+func ExampleGenerateFormData() {
+	// Mock the random reader for predictable output.
+	// NOTE: do not do this on real code.
+	rand.Reader = mock.NewRandReader([]byte(`randomseed`))
+
+	var data = map[string][]byte{
+		`name`: []byte(`test.txt`),
+		`size`: []byte(`42`),
+	}
+
+	var (
+		contentType string
+		body        string
+		err         error
+	)
+	contentType, body, err = libhttp.GenerateFormData(data)
+	if err != nil {
+		log.Fatal(err)
+	}
+	fmt.Println(`contentType:`, contentType)
+	fmt.Println(`body:`)
+	fmt.Println(strings.ReplaceAll(body, "\r\n", "\n"))
+	// Output:
+	// contentType: multipart/form-data; boundary=72616e646f6d7365656472616e646f6d7365656472616e646f6d73656564
+	// body:
+	// --72616e646f6d7365656472616e646f6d7365656472616e646f6d73656564
+	// Content-Disposition: form-data; name="name"
+	//
+	// test.txt
+	// --72616e646f6d7365656472616e646f6d7365656472616e646f6d73656564
+	// Content-Disposition: form-data; name="size"
+	//
+	// 42
+	// --72616e646f6d7365656472616e646f6d7365656472616e646f6d73656564--
+}
diff --git a/lib/http/client_request.go b/lib/http/client_request.go
index 03496e45..635c88da 100644
--- a/lib/http/client_request.go
+++ b/lib/http/client_request.go
@@ -113,7 +113,7 @@ func (creq *ClientRequest) toHTTPRequest(client *Client) (httpReq *http.Request,
 		case RequestTypeMultipartForm:
 			paramsAsMultipart, ok := creq.Params.(map[string][]byte)
 			if ok {
-				contentType, strBody, err = generateFormData(paramsAsMultipart)
+				contentType, strBody, err = GenerateFormData(paramsAsMultipart)
 				if err != nil {
 					return nil, fmt.Errorf("%s: %w", logp, err)
 				}