feat: support minimal prefer header

README.md

@@ -29,6 +29,7 @@ Features include:
   - Generates JSON Schema from Go types
   - Automatic input model validation & error handling
 - Dependency injection for loggers, datastores, etc
+- Automatic handling of `Prefer: return=minimal` from [RFC 7240](https://tools.ietf.org/html/rfc7240#section-4.2)
 - Documentation generation using [RapiDoc](https://mrin9.github.io/RapiDoc/), [ReDoc](https://github.com/Redocly/redoc), or [SwaggerUI](https://swagger.io/tools/swagger-ui/)
 - CLI built-in, configured via arguments or environment variables
   - Set via e.g. `-p 8000`, `--port=8000`, or `SERVICE_PORT=8000`
@@ -574,6 +575,7 @@ g := gin.New()
 g.Use(huma.Recovery())
 g.Use(huma.LogMiddleware(nil, nil))
 g.Use(cors.Default())
+g.Use(huma.PreferMinimalMiddleware())
 g.NoRoute(huma.Handler404)
 r := huma.NewRouterWithGin(g, &huma.OpenAPI{
 	Title:   "Notes API",

middelware.go

@@ -117,3 +117,38 @@ func Handler404(c *gin.Context) {
 		Message: "Not found",
 	})
 }
+
+type minimalWriter struct {
+	gin.ResponseWriter
+	w http.ResponseWriter
+}
+
+func (w *minimalWriter) Write(data []byte) (int, error) {
+	if w.Status() == http.StatusNoContent {
+		return 0, nil
+	}
+
+	return w.ResponseWriter.Write(data)
+}
+
+func (w *minimalWriter) WriteHeader(statusCode int) {
+	if statusCode >= 200 && statusCode < 300 {
+		statusCode = http.StatusNoContent
+	}
+
+	w.ResponseWriter.WriteHeader(statusCode)
+}
+
+// PreferMinimalMiddleware will remove the response body and return 204 No
+// Content for any 2xx response where the request had the Prefer: return=minimal
+// set on the request.
+func PreferMinimalMiddleware() func(*gin.Context) {
+	return func(c *gin.Context) {
+		// Wrap the response writer
+		if c.GetHeader("prefer") == "return=minimal" {
+			c.Writer = &minimalWriter{ResponseWriter: c.Writer}
+		}
+
+		c.Next()
+	}
+}

middleware_test.go

@@ -37,6 +37,42 @@ func TestRecoveryMiddleware(t *testing.T) {
 	assert.Equal(t, "application/json; charset=utf-8", w.Result().Header.Get("content-type"))
 }
 
+func TestPreferMinimalMiddleware(t *testing.T) {
+	r := NewTestRouter(t)
+	r.GinEngine().Use(PreferMinimalMiddleware())
+
+	r.Resource("/test").Get("desc", func() string {
+		return "Hello, test"
+	})
+
+	r.Resource("/non200", ResponseText(http.StatusBadRequest, "desc")).Get("desc", func() string {
+		return "Error details"
+	})
+
+	// Normal request
+	w := httptest.NewRecorder()
+	req, _ := http.NewRequest(http.MethodGet, "/test", nil)
+	r.ServeHTTP(w, req)
+	assert.Equal(t, http.StatusOK, w.Code)
+	assert.NotEmpty(t, w.Body.String())
+
+	// Prefer minimal should return 204 No Content
+	w = httptest.NewRecorder()
+	req, _ = http.NewRequest(http.MethodGet, "/test", nil)
+	req.Header.Add("prefer", "return=minimal")
+	r.ServeHTTP(w, req)
+	assert.Equal(t, http.StatusNoContent, w.Code)
+	assert.Empty(t, w.Body.String())
+
+	// Prefer minimal which can still return non-200 response bodies
+	w = httptest.NewRecorder()
+	req, _ = http.NewRequest(http.MethodGet, "/non200", nil)
+	req.Header.Add("prefer", "return=minimal")
+	r.ServeHTTP(w, req)
+	assert.Equal(t, http.StatusBadRequest, w.Code)
+	assert.NotEmpty(t, w.Body.String())
+}
+
 func TestHandler404(t *testing.T) {
 	g := gin.New()
 	g.NoRoute(Handler404)

router.go

@@ -218,6 +218,7 @@ func NewRouter(api *OpenAPI) *Router {
 	g.Use(Recovery())
 	g.Use(LogMiddleware(nil, nil))
 	g.Use(cors.Default())
+	g.Use(PreferMinimalMiddleware())
 	g.NoRoute(Handler404)
 	return NewRouterWithGin(g, api)
 }