🔥 Add support for application/problem+json (#2704)

🔥 Add support for custom JSON content headers

client.go

@@ -460,12 +460,16 @@ func (a *Agent) BodyStream(bodyStream io.Reader, bodySize int) *Agent {
 }
 
 // JSON sends a JSON request.
-func (a *Agent) JSON(v interface{}) *Agent {
+func (a *Agent) JSON(v interface{}, ctype ...string) *Agent {
 	if a.jsonEncoder == nil {
 		a.jsonEncoder = json.Marshal
 	}
 
-	a.req.Header.SetContentType(MIMEApplicationJSON)
+	if len(ctype) > 0 {
+		a.req.Header.SetContentType(ctype[0])
+	} else {
+		a.req.Header.SetContentType(MIMEApplicationJSON)
+	}
 
 	if body, err := a.jsonEncoder(v); err != nil {
 		a.errs = append(a.errs, err)

client_test.go

@@ -651,6 +651,7 @@ func Test_Client_Agent_RetryIf(t *testing.T) {
 
 func Test_Client_Agent_Json(t *testing.T) {
 	t.Parallel()
+	// Test without ctype parameter
 	handler := func(c *Ctx) error {
 		utils.AssertEqual(t, MIMEApplicationJSON, string(c.Request().Header.ContentType()))
 
@@ -662,6 +663,19 @@ func Test_Client_Agent_Json(t *testing.T) {
 	}
 
 	testAgent(t, handler, wrapAgent, `{"success":true}`)
+
+	// Test with ctype parameter
+	handler = func(c *Ctx) error {
+		utils.AssertEqual(t, "application/problem+json", string(c.Request().Header.ContentType()))
+
+		return c.Send(c.Request().Body())
+	}
+
+	wrapAgent = func(a *Agent) {
+		a.JSON(data{Success: true}, "application/problem+json")
+	}
+
+	testAgent(t, handler, wrapAgent, `{"success":true}`)
 }
 
 func Test_Client_Agent_Json_Error(t *testing.T) {

ctx.go

@@ -373,6 +373,7 @@ func decoderBuilder(parserConfig ParserConfig) interface{} {
 // BodyParser binds the request body to a struct.
 // It supports decoding the following content types based on the Content-Type header:
 // application/json, application/xml, application/x-www-form-urlencoded, multipart/form-data
+// All JSON extenstion mime types are supported (eg. application/problem+json)
 // If none of the content types above are matched, it will return a ErrUnprocessableEntity error
 func (c *Ctx) BodyParser(out interface{}) error {
 	// Get content-type
@@ -380,8 +381,14 @@ func (c *Ctx) BodyParser(out interface{}) error {
 
 	ctype = utils.ParseVendorSpecificContentType(ctype)
 
+	// Only use ctype string up to and excluding byte ';'
+	ctypeEnd := strings.IndexByte(ctype, ';')
+	if ctypeEnd != -1 {
+		ctype = ctype[:ctypeEnd]
+	}
+
 	// Parse body accordingly
-	if strings.HasPrefix(ctype, MIMEApplicationJSON) {
+	if strings.HasSuffix(ctype, "json") {
 		return c.app.config.JSONDecoder(c.Body(), out)
 	}
 	if strings.HasPrefix(ctype, MIMEApplicationForm) {
@@ -886,14 +893,20 @@ func (c *Ctx) Is(extension string) bool {
 // Array and slice values encode as JSON arrays,
 // except that []byte encodes as a base64-encoded string,
 // and a nil slice encodes as the null JSON value.
-// This method also sets the content header to application/json.
-func (c *Ctx) JSON(data interface{}) error {
+// If the ctype parameter is given, this method will set the
+// Content-Type header equal to ctype. If ctype is not given,
+// The Content-Type header will be set to application/json.
+func (c *Ctx) JSON(data interface{}, ctype ...string) error {
 	raw, err := c.app.config.JSONEncoder(data)
 	if err != nil {
 		return err
 	}
 	c.fasthttp.Response.SetBodyRaw(raw)
-	c.fasthttp.Response.Header.SetContentType(MIMEApplicationJSON)
+	if len(ctype) > 0 {
+		c.fasthttp.Response.Header.SetContentType(ctype[0])
+	} else {
+		c.fasthttp.Response.Header.SetContentType(MIMEApplicationJSON)
+	}
 	return nil
 }
 

ctx_test.go

@@ -574,6 +574,9 @@ func Test_Ctx_BodyParser(t *testing.T) {
 	testDecodeParser(MIMEApplicationForm, "name=john")
 	testDecodeParser(MIMEMultipartForm+`;boundary="b"`, "--b\r\nContent-Disposition: form-data; name=\"name\"\r\n\r\njohn\r\n--b--")
 
+	// Ensure JSON extension MIME type gets parsed as JSON
+	testDecodeParser("application/problem+json", `{"name":"john"}`)
+
 	testDecodeParserError := func(contentType, body string) {
 		c.Request().Header.SetContentType(contentType)
 		c.Request().SetBody([]byte(body))
@@ -708,6 +711,30 @@ func Benchmark_Ctx_BodyParser_JSON(b *testing.B) {
 	utils.AssertEqual(b, "john", d.Name)
 }
 
+// go test -v -run=^$ -bench=Benchmark_Ctx_BodyParser_JSON_Extension -benchmem -count=4
+func Benchmark_Ctx_BodyParser_JSON_Extension(b *testing.B) {
+	app := New()
+	c := app.AcquireCtx(&fasthttp.RequestCtx{})
+	defer app.ReleaseCtx(c)
+	type Demo struct {
+		Name string `json:"name"`
+	}
+	body := []byte(`{"name":"john"}`)
+	c.Request().SetBody(body)
+	c.Request().Header.SetContentType("application/problem+json")
+	c.Request().Header.SetContentLength(len(body))
+	d := new(Demo)
+
+	b.ReportAllocs()
+	b.ResetTimer()
+
+	for n := 0; n < b.N; n++ {
+		_ = c.BodyParser(d) //nolint:errcheck // It is fine to ignore the error here as we check it once further below
+	}
+	utils.AssertEqual(b, nil, c.BodyParser(d))
+	utils.AssertEqual(b, "john", d.Name)
+}
+
 // go test -v -run=^$ -bench=Benchmark_Ctx_BodyParser_XML -benchmem -count=4
 func Benchmark_Ctx_BodyParser_XML(b *testing.B) {
 	app := New()
@@ -2927,6 +2954,7 @@ func Test_Ctx_JSON(t *testing.T) {
 
 	utils.AssertEqual(t, true, c.JSON(complex(1, 1)) != nil)
 
+	// Test without ctype
 	err := c.JSON(Map{ // map has no order
 		"Name": "Grame",
 		"Age":  20,
@@ -2935,6 +2963,15 @@ func Test_Ctx_JSON(t *testing.T) {
 	utils.AssertEqual(t, `{"Age":20,"Name":"Grame"}`, string(c.Response().Body()))
 	utils.AssertEqual(t, "application/json", string(c.Response().Header.Peek("content-type")))
 
+	// Test with ctype
+	err = c.JSON(Map{ // map has no order
+		"Name": "Grame",
+		"Age":  20,
+	}, "application/problem+json")
+	utils.AssertEqual(t, nil, err)
+	utils.AssertEqual(t, `{"Age":20,"Name":"Grame"}`, string(c.Response().Body()))
+	utils.AssertEqual(t, "application/problem+json", string(c.Response().Header.Peek("content-type")))
+
 	testEmpty := func(v interface{}, r string) {
 		err := c.JSON(v)
 		utils.AssertEqual(t, nil, err)
@@ -2990,6 +3027,30 @@ func Benchmark_Ctx_JSON(b *testing.B) {
 	utils.AssertEqual(b, `{"Name":"Grame","Age":20}`, string(c.Response().Body()))
 }
 
+// go test -run=^$ -bench=Benchmark_Ctx_JSON_Ctype -benchmem -count=4
+func Benchmark_Ctx_JSON_Ctype(b *testing.B) {
+	app := New()
+	c := app.AcquireCtx(&fasthttp.RequestCtx{})
+	defer app.ReleaseCtx(c)
+	type SomeStruct struct {
+		Name string
+		Age  uint8
+	}
+	data := SomeStruct{
+		Name: "Grame",
+		Age:  20,
+	}
+	var err error
+	b.ReportAllocs()
+	b.ResetTimer()
+	for n := 0; n < b.N; n++ {
+		err = c.JSON(data, "application/problem+json")
+	}
+	utils.AssertEqual(b, nil, err)
+	utils.AssertEqual(b, `{"Name":"Grame","Age":20}`, string(c.Response().Body()))
+	utils.AssertEqual(b, "application/problem+json", string(c.Response().Header.Peek("content-type")))
+}
+
 // go test -run Test_Ctx_JSONP
 func Test_Ctx_JSONP(t *testing.T) {
 	t.Parallel()

docs/api/ctx.md

@@ -797,11 +797,11 @@ app.Get("/", func(c *fiber.Ctx) error {
 Converts any **interface** or **string** to JSON using the [encoding/json](https://pkg.go.dev/encoding/json) package.
 
 :::info
-JSON also sets the content header to **application/json**.
+JSON also sets the content header to the `ctype` parameter. If no `ctype` is passed in, the header is set to **application/json**.
 :::
 
 ```go title="Signature"
-func (c *Ctx) JSON(data interface{}) error
+func (c *Ctx) JSON(data interface{}, ctype ...string) error
 ```
 
 ```go title="Example"
@@ -827,6 +827,22 @@ app.Get("/json", func(c *fiber.Ctx) error {
   })
   // => Content-Type: application/json
   // => "{"name": "Grame", "age": 20}"
+
+  return c.JSON(fiber.Map{
+    "type": "https://example.com/probs/out-of-credit",
+    "title": "You do not have enough credit.",
+    "status": 403,
+    "detail": "Your current balance is 30, but that costs 50.",
+    "instance": "/account/12345/msgs/abc",
+  }, "application/problem+json")
+  // => Content-Type: application/problem+json
+  // => "{
+  // =>     "type": "https://example.com/probs/out-of-credit",
+  // =>     "title": "You do not have enough credit.",
+  // =>     "status": 403,
+  // =>     "detail": "Your current balance is 30, but that costs 50.",
+  // =>     "instance": "/account/12345/msgs/abc",
+  // => }"
 })
 ```