sync from project

magic/json.go

@@ -2,8 +2,15 @@ package magic
 
 import (
 	"encoding/json"
-	"io"
 	"net/http"
+	"reflect"
+	"strings"
+
+	"github.com/go-playground/validator/v10"
+)
+
+var (
+	jsonValidator = NewValidator("json")
 )
 
 type JsonDecodeError struct {
@@ -18,10 +25,25 @@ func (err JsonDecodeError) WriteResponse(rw http.ResponseWriter) {
 	rw.WriteHeader(http.StatusBadRequest)
 }
 
-type Json[T any] struct {
-	Data T
+type ValidateError []string
+
+func (err ValidateError) Error() string {
+	return "invalid or missing fields: [" + strings.Join(err, ", ") + "]"
 }
 
+func (v ValidateError) WriteResponse(w http.ResponseWriter) {
+	w.Header().Set("Content-Type", "text/plain; charset=utf-8")
+	w.WriteHeader(http.StatusBadRequest)
+	w.Write([]byte(v.Error()))
+}
+
+type Json[T any] struct {
+	Data T `json:"data"`
+}
+
+// TakeRequestBody is a marker method to indicate that this extractor takes the request body.
+func (j Json[T]) TakeRequestBody() {}
+
 func NewJson[T any](data T) Json[T] {
 	return Json[T]{
 		Data: data,
@@ -29,35 +51,41 @@ func NewJson[T any](data T) Json[T] {
 }
 
 func (data *Json[T]) FromRequest(request *http.Request) error {
+	if request.Body == nil {
+		panic("body is already taken")
+	}
+
 	bodyReader := request.Body
 	defer bodyReader.Close()
 
-	request.Body = http.NoBody
+	request.Body = nil
 
 	if err := json.NewDecoder(bodyReader).Decode(&data.Data); err != nil {
 		return JsonDecodeError{inner: err}
 	}
 
+	value := reflect.ValueOf(data.Data)
+	if value.Kind() == reflect.Struct || (value.Kind() == reflect.Ptr && value.Elem().Kind() == reflect.Struct) {
+		if err := jsonValidator.StructCtx(request.Context(), data.Data); err == nil {
+			return nil
+		} else if validateErr, isValidateErr := err.(validator.ValidationErrors); isValidateErr {
+			fields := make([]string, len(validateErr))
+			for idx, err := range validateErr {
+				fields[idx] = err.Field()
+			}
+			return ValidateError(fields)
+		} else {
+			return err
+		}
+	}
+
 	return nil
 }
 
-type counter struct {
-	counter int64
-}
-
-func (c *counter) Write(b []byte) (int, error) {
-	n := len(b)
-	c.counter += int64(n)
-
-	return n, nil
-}
-
-func (container Json[T]) Write(w io.Writer) (int64, error) {
-	counter := &counter{}
-	err := json.NewEncoder(io.MultiWriter(counter, w)).Encode(container.Data)
-	return counter.counter, err
-}
-
-func (json Json[T]) WriteResponse(w http.ResponseWriter) {
-	json.Write(w)
+func (data *Json[T]) WriteResponse(w http.ResponseWriter) {
+	w.Header().Set("Content-Type", "application/json")
+	if data == nil {
+		return
+	}
+	json.NewEncoder(w).Encode(data)
 }