chore(header): Add support for RFC 9512: application/yaml (#3851)

* fix(binding): support application/yaml

RFC 9512 defines application/yaml as the official YAML MIME type.
application/x-yaml is deprecated. In this commit, we ensure it is
recognized correctly in Content-Type.

* fix(render): use application/yaml when rendering YAML

As per RFC 9512, application/x-yaml is now deprecated and applications
should use application/yaml. This commit fix the Content-Type header
when rendering YAML.

binding/binding.go

@@ -21,6 +21,7 @@ const (
 	MIMEMSGPACK           = "application/x-msgpack"
 	MIMEMSGPACK2          = "application/msgpack"
 	MIMEYAML              = "application/x-yaml"
+	MIMEYAML2             = "application/yaml"
 	MIMETOML              = "application/toml"
 )
 
@@ -102,7 +103,7 @@ func Default(method, contentType string) Binding {
 		return ProtoBuf
 	case MIMEMSGPACK, MIMEMSGPACK2:
 		return MsgPack
-	case MIMEYAML:
+	case MIMEYAML, MIMEYAML2:
 		return YAML
 	case MIMETOML:
 		return TOML

binding/binding_nomsgpack.go

@@ -19,6 +19,7 @@ const (
 	MIMEMultipartPOSTForm = "multipart/form-data"
 	MIMEPROTOBUF          = "application/x-protobuf"
 	MIMEYAML              = "application/x-yaml"
+	MIMEYAML2             = "application/yaml"
 	MIMETOML              = "application/toml"
 )
 
@@ -96,7 +97,7 @@ func Default(method, contentType string) Binding {
 		return XML
 	case MIMEPROTOBUF:
 		return ProtoBuf
-	case MIMEYAML:
+	case MIMEYAML, MIMEYAML2:
 		return YAML
 	case MIMEMultipartPOSTForm:
 		return FormMultipart

binding/binding_test.go

@@ -164,6 +164,8 @@ func TestBindingDefault(t *testing.T) {
 
 	assert.Equal(t, YAML, Default("POST", MIMEYAML))
 	assert.Equal(t, YAML, Default("PUT", MIMEYAML))
+	assert.Equal(t, YAML, Default("POST", MIMEYAML2))
+	assert.Equal(t, YAML, Default("PUT", MIMEYAML2))
 
 	assert.Equal(t, TOML, Default("POST", MIMETOML))
 	assert.Equal(t, TOML, Default("PUT", MIMETOML))

context_test.go

@@ -1060,7 +1060,7 @@ func TestContextRenderUTF8Attachment(t *testing.T) {
 }
 
 // TestContextRenderYAML tests that the response is serialized as YAML
-// and Content-Type is set to application/x-yaml
+// and Content-Type is set to application/yaml
 func TestContextRenderYAML(t *testing.T) {
 	w := httptest.NewRecorder()
 	c, _ := CreateTestContext(w)
@@ -1069,7 +1069,7 @@ func TestContextRenderYAML(t *testing.T) {
 
 	assert.Equal(t, http.StatusCreated, w.Code)
 	assert.Equal(t, "foo: bar\n", w.Body.String())
-	assert.Equal(t, "application/x-yaml; charset=utf-8", w.Header().Get("Content-Type"))
+	assert.Equal(t, "application/yaml; charset=utf-8", w.Header().Get("Content-Type"))
 }
 
 // TestContextRenderTOML tests that the response is serialized as TOML
@@ -1217,7 +1217,7 @@ func TestContextNegotiationWithYAML(t *testing.T) {
 
 	assert.Equal(t, http.StatusOK, w.Code)
 	assert.Equal(t, "foo: bar\n", w.Body.String())
-	assert.Equal(t, "application/x-yaml; charset=utf-8", w.Header().Get("Content-Type"))
+	assert.Equal(t, "application/yaml; charset=utf-8", w.Header().Get("Content-Type"))
 }
 
 func TestContextNegotiationWithTOML(t *testing.T) {

render/render_test.go

@@ -280,12 +280,12 @@ b:
 	d: [3, 4]
 	`
 	(YAML{data}).WriteContentType(w)
-	assert.Equal(t, "application/x-yaml; charset=utf-8", w.Header().Get("Content-Type"))
+	assert.Equal(t, "application/yaml; charset=utf-8", w.Header().Get("Content-Type"))
 
 	err := (YAML{data}).Render(w)
 	assert.NoError(t, err)
 	assert.Equal(t, "|4-\n    a : Easy!\n    b:\n    \tc: 2\n    \td: [3, 4]\n    \t\n", w.Body.String())
-	assert.Equal(t, "application/x-yaml; charset=utf-8", w.Header().Get("Content-Type"))
+	assert.Equal(t, "application/yaml; charset=utf-8", w.Header().Get("Content-Type"))
 }
 
 type fail struct{}

render/yaml.go

@@ -15,7 +15,7 @@ type YAML struct {
 	Data any
 }
 
-var yamlContentType = []string{"application/x-yaml; charset=utf-8"}
+var yamlContentType = []string{"application/yaml; charset=utf-8"}
 
 // Render (YAML) marshals the given interface object and writes data with custom ContentType.
 func (r YAML) Render(w http.ResponseWriter) error {