c.Request.Body is a stream, EOF after read from, example in Golang Gin

gin_bind.go

package main

import (
	"encoding/json"
	"fmt"
	"github.com/gin-gonic/gin"
	"net/http"
)

type SimpleUser struct {
	Id       int    `json:"id"`
	Email    string `json:"email"`
	Password string `json:"password"`
}

func Cors() gin.HandlerFunc {
	return func(c *gin.Context) {
		c.Writer.Header().Add("Access-Control-Allow-Origin", "*")
		c.Writer.Header().Add("Content-Type", "application/json")
		c.Next()
	}
}

func handleErrors(c *gin.Context) {
	c.Next()
	errorToPrint := c.Errors.ByType(gin.ErrorTypePublic).Last()
	if errorToPrint != nil {
		c.JSON(500, gin.H{
			"status":  500,
			"message": errorToPrint.Error(),
		})
	}
}

func GetMainEngine() *gin.Engine {
	r := gin.Default()
	r.Use(handleErrors)
	r.Use(Cors())
	v1 := r.Group("api/v1")
	{
		v1.POST("/users", CreateUser)
	}

	v1.Use()

	return r
}

func main() {
	GetMainEngine().Run(":8080")
}

func OptionsDelPostPut(c *gin.Context) {
	c.Writer.Header().Set("Access-Control-Allow-Methods", "DELETE,POST, PUT")
	//c.Writer.Header().Set("Access-Control-Allow-Headers", "Content-Type")
	c.Next()
}

func CreateUser(c *gin.Context) {
	fmt.Println("Raw Request Body : %s", c.Request.Body)

	var tuser SimpleUser
	decoder := json.NewDecoder(c.Request.Body)
	err := decoder.Decode(&tuser)
	if err != nil {
		fmt.Printf("error %s", err)
		c.JSON(501, gin.H{"error": err})
	}
	//fmt.Printf("Decode Body %v\n\n", tuser)
	fmt.Printf("Decoded Body Request Email : %v\n", tuser.Email)
	fmt.Printf("Decoded Body Request Password : %v\n", tuser.Password)

	var su SimpleUser
	err = c.BindJSON(&su) 
	// err = Bind error EOF
	// why not set?!
	//fmt.Println("%v\n\n", su)
	fmt.Printf("Bind Email - Why not Set? %v\n", su.Email)
	fmt.Printf("Bind Password  - Why not Set? %v\n", su.Password)

	//email := c.PostForm("email")     // not expected
	//email = c.Params.ByName("email") // not expected

	c.JSON(http.StatusCreated, gin.H{"success": "success"})
}

gin_bind_test.go

package main

import (
	"bytes"
	"net/http"
	"net/http/httptest"
	"testing"
)

func TestWhyNotBinding(t *testing.T) {
	oParams := `{"email": "testEmail", "password": "testPassword"}`
	req, _ := http.NewRequest("POST", "/api/v1/users", bytes.NewBufferString(oParams))
	//req.Header.Add("Content-Type", "application/json; charset=UTF-8")
	req.Header.Add("Content-Type", "application/json")

	resp := httptest.NewRecorder()
	ts := GetMainEngine()
	ts.ServeHTTP(resp, req)
}