Add direct download option when serving static files (gofiber#1729)

* enable download for app.Static


wording

* Add unit test.

Co-authored-by: Muhammed Efe Çetin <efectn@protonmail.com>

app.go

@@ -379,6 +379,10 @@ type Static struct {
 	// Optional. Default value false.
 	Browse bool `json:"browse"`
 
+	// When set to true, enables direct download.
+	// Optional. Default value false.
+	Download bool `json:"download"`
+
 	// The name of the index file for serving a directory.
 	// Optional. Default value "index.html".
 	Index string `json:"index"`

app_test.go

@@ -678,6 +678,22 @@ func Test_App_Static_MaxAge(t *testing.T) {
 	utils.AssertEqual(t, "public, max-age=100", resp.Header.Get(HeaderCacheControl), "CacheControl Control")
 }
 
+// go test -run Test_App_Static_Download
+func Test_App_Static_Download(t *testing.T) {
+	app := New()
+	c := app.AcquireCtx(&fasthttp.RequestCtx{})
+	defer app.ReleaseCtx(c)
+
+	app.Static("/fiber.png", "./.github/testdata/fs/img/fiber.png", Static{Download: true})
+
+	resp, err := app.Test(httptest.NewRequest("GET", "/fiber.png", nil))
+	utils.AssertEqual(t, nil, err, "app.Test(req)")
+	utils.AssertEqual(t, 200, resp.StatusCode, "Status code")
+	utils.AssertEqual(t, false, resp.Header.Get(HeaderContentLength) == "")
+	utils.AssertEqual(t, "image/png", resp.Header.Get(HeaderContentType))
+	utils.AssertEqual(t, `attachment`, resp.Header.Get(HeaderContentDisposition))
+}
+
 // go test -run Test_App_Static_Group
 func Test_App_Static_Group(t *testing.T) {
 	app := New()

router.go

@@ -377,6 +377,10 @@ func (app *App) registerStatic(prefix, root string, config ...Static) Router {
 		}
 		// Serve file
 		fileHandler(c.fasthttp)
+		// Sets the response Content-Disposition header to attachment if the Download option is true
+		if len(config) > 0 && config[0].Download {
+			c.Attachment()
+		}
 		// Return request if found and not forbidden
 		status := c.fasthttp.Response.StatusCode()
 		if status != StatusNotFound && status != StatusForbidden {