Fix switch language (#14484)

Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: Lauris BH <lauris@nix.lv>

modules/middlewares/locale.go

@@ -15,24 +15,22 @@ import (
 
 // Locale handle locale
 func Locale(resp http.ResponseWriter, req *http.Request) translation.Locale {
-	hasCookie := false
-
 	// 1. Check URL arguments.
 	lang := req.URL.Query().Get("lang")
+	var changeLang = lang != ""
 
 	// 2. Get language information from cookies.
 	if len(lang) == 0 {
 		ck, _ := req.Cookie("lang")
 		if ck != nil {
 			lang = ck.Value
-			hasCookie = true
 		}
 	}
 
 	// Check again in case someone modify by purpose.
 	if lang != "" && !i18n.IsExist(lang) {
 		lang = ""
-		hasCookie = false
+		changeLang = false
 	}
 
 	// 3. Get language information from 'Accept-Language'.
@@ -43,8 +41,8 @@ func Locale(resp http.ResponseWriter, req *http.Request) translation.Locale {
 		lang = tag.String()
 	}
 
-	if !hasCookie {
-		req.AddCookie(NewCookie("lang", lang, 1<<31-1))
+	if changeLang {
+		SetCookie(resp, "lang", lang, 1<<31-1)
 	}
 
 	return translation.NewLocale(lang)