Remove default charset from 'application/json' Content-Type header (#…

…2568)

Fixes #2567

context.go

@@ -489,7 +489,7 @@ func (c *context) jsonPBlob(code int, callback string, i interface{}) (err error
 }
 
 func (c *context) json(code int, i interface{}, indent string) error {
-	c.writeContentType(MIMEApplicationJSONCharsetUTF8)
+	c.writeContentType(MIMEApplicationJSON)
 	c.response.Status = code
 	return c.echo.JSONSerializer.Serialize(c, i, indent)
 }
@@ -507,7 +507,7 @@ func (c *context) JSONPretty(code int, i interface{}, indent string) (err error)
 }
 
 func (c *context) JSONBlob(code int, b []byte) (err error) {
-	return c.Blob(code, MIMEApplicationJSONCharsetUTF8, b)
+	return c.Blob(code, MIMEApplicationJSON, b)
 }
 
 func (c *context) JSONP(code int, callback string, i interface{}) (err error) {

context_test.go

@@ -154,7 +154,7 @@ func TestContextJSON(t *testing.T) {
 	err := c.JSON(http.StatusOK, user{1, "Jon Snow"})
 	if assert.NoError(t, err) {
 		assert.Equal(t, http.StatusOK, rec.Code)
-		assert.Equal(t, MIMEApplicationJSONCharsetUTF8, rec.Header().Get(HeaderContentType))
+		assert.Equal(t, MIMEApplicationJSON, rec.Header().Get(HeaderContentType))
 		assert.Equal(t, userJSON+"\n", rec.Body.String())
 	}
 }
@@ -178,7 +178,7 @@ func TestContextJSONPrettyURL(t *testing.T) {
 	err := c.JSON(http.StatusOK, user{1, "Jon Snow"})
 	if assert.NoError(t, err) {
 		assert.Equal(t, http.StatusOK, rec.Code)
-		assert.Equal(t, MIMEApplicationJSONCharsetUTF8, rec.Header().Get(HeaderContentType))
+		assert.Equal(t, MIMEApplicationJSON, rec.Header().Get(HeaderContentType))
 		assert.Equal(t, userJSONPretty+"\n", rec.Body.String())
 	}
 }
@@ -192,7 +192,7 @@ func TestContextJSONPretty(t *testing.T) {
 	err := c.JSONPretty(http.StatusOK, user{1, "Jon Snow"}, "  ")
 	if assert.NoError(t, err) {
 		assert.Equal(t, http.StatusOK, rec.Code)
-		assert.Equal(t, MIMEApplicationJSONCharsetUTF8, rec.Header().Get(HeaderContentType))
+		assert.Equal(t, MIMEApplicationJSON, rec.Header().Get(HeaderContentType))
 		assert.Equal(t, userJSONPretty+"\n", rec.Body.String())
 	}
 }
@@ -213,7 +213,7 @@ func TestContextJSONWithEmptyIntent(t *testing.T) {
 	err := c.json(http.StatusOK, user{1, "Jon Snow"}, emptyIndent)
 	if assert.NoError(t, err) {
 		assert.Equal(t, http.StatusOK, rec.Code)
-		assert.Equal(t, MIMEApplicationJSONCharsetUTF8, rec.Header().Get(HeaderContentType))
+		assert.Equal(t, MIMEApplicationJSON, rec.Header().Get(HeaderContentType))
 		assert.Equal(t, buf.String(), rec.Body.String())
 	}
 }
@@ -244,7 +244,7 @@ func TestContextJSONBlob(t *testing.T) {
 	err = c.JSONBlob(http.StatusOK, data)
 	if assert.NoError(t, err) {
 		assert.Equal(t, http.StatusOK, rec.Code)
-		assert.Equal(t, MIMEApplicationJSONCharsetUTF8, rec.Header().Get(HeaderContentType))
+		assert.Equal(t, MIMEApplicationJSON, rec.Header().Get(HeaderContentType))
 		assert.Equal(t, userJSON, rec.Body.String())
 	}
 }
@@ -533,7 +533,7 @@ func TestContext_JSON_CommitsCustomResponseCode(t *testing.T) {
 
 	if assert.NoError(t, err) {
 		assert.Equal(t, http.StatusCreated, rec.Code)
-		assert.Equal(t, MIMEApplicationJSONCharsetUTF8, rec.Header().Get(HeaderContentType))
+		assert.Equal(t, MIMEApplicationJSON, rec.Header().Get(HeaderContentType))
 		assert.Equal(t, userJSON+"\n", rec.Body.String())
 	}
 }

echo.go

@@ -169,7 +169,12 @@ const (
 
 // MIME types
 const (
-	MIMEApplicationJSON                  = "application/json"
+	// MIMEApplicationJSON JavaScript Object Notation (JSON) https://www.rfc-editor.org/rfc/rfc8259
+	MIMEApplicationJSON = "application/json"
+	// Deprecated: Please use MIMEApplicationJSON instead. JSON should be encoded using UTF-8 by default.
+	// No "charset" parameter is defined for this registration.
+	// Adding one really has no effect on compliant recipients.
+	// See RFC 8259, section 8.1. https://datatracker.ietf.org/doc/html/rfc8259#section-8.1
 	MIMEApplicationJSONCharsetUTF8       = MIMEApplicationJSON + "; " + charsetUTF8
 	MIMEApplicationJavaScript            = "application/javascript"
 	MIMEApplicationJavaScriptCharsetUTF8 = MIMEApplicationJavaScript + "; " + charsetUTF8

middleware/decompress_test.go

@@ -131,7 +131,7 @@ func TestDecompressSkipper(t *testing.T) {
 	rec := httptest.NewRecorder()
 	c := e.NewContext(req, rec)
 	e.ServeHTTP(rec, req)
-	assert.Equal(t, rec.Header().Get(echo.HeaderContentType), echo.MIMEApplicationJSONCharsetUTF8)
+	assert.Equal(t, rec.Header().Get(echo.HeaderContentType), echo.MIMEApplicationJSON)
 	reqBody, err := io.ReadAll(c.Request().Body)
 	assert.NoError(t, err)
 	assert.Equal(t, body, string(reqBody))