ShouldBindJSON bind struct, header "content-type application/json", no Response?

[AutumnFlowerTheLeft]

ide debug log
ShouldBindJSON.txt

ShouldBind.txt

I use ApiFox, modify Content-Type to "application/json", can't be mapping into the struct by two functions(ShouldBindJSON and ShouldBind)

Struct, form and json setting.

type register struct {
	Username        string `form:"username" json:"username" `
	Useremail       string `form:"useremail" json:"useremail"`
	Passowrd        string `form:"passowrd" json:"password"`
	Confirmpassword string `form:"confirmpassword" json:"confirmpassword"`
}

func *RegisterUser()

func RegisterUser(c *gin.Context) {
	var reg register

	//c.Header("Content-Type", "application/json")
	e := c.ShouldBind(&reg)
	if e != nil {
		slog.Error("ERROR", "ERRORS", e)
	}
	slog.Info("INFO", "*RegisterUser() UserName", reg.Username, "UserEmail", reg.Useremail)
}

If the server uses ShouldBind, and the client requests to remove the application/json, it can access normally.

Using the Vue, JavaScript function *fetch() code to make a request, it still doesn't work.
"Content-Type": "application/json"

 const handleSubmit = ({values, errors}) => {
      console.log('values:', values, '\nerrors:', errors)
      // https://api.chingluennetwork.org
      $fetch('/api/v1/register/',{
        method: 'POST',
        body:{
          username:values.name,
          useremail:values.email,
          passowrd: values.password,
          confirmpassword: values.password2
        }
      })
    }

Sometimes it succeeds or fails.

2025/02/08 23:15:37 INFO INFO "*RegisterUser() UserName"=qwwqewq [email protected]
[GIN] 2025/02/08 - 23:15:37 | 200 |            0s |       127.0.0.1 | POST     "/api/v1/register/"

Request head

POST /api/v1/register/ HTTP/1.1
Accept-Encoding: gzip, deflate, br, zstd
Accept-Language: zh-CN,zh;q=0.9,en-US;q=0.8,en;q=0.7
Connection: keep-alive
Content-Length: 96
Host: localhost:3000
Origin: http://localhost:3000
Referer: http://localhost:3000/oauth/register
Sec-Fetch-Dest: empty
Sec-Fetch-Mode: cors
Sec-Fetch-Site: same-origin
User-Agent: Mozilla/5.0 (Linux; Android 6.0; Nexus 5 Build/MRA58N) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/132.0.0.0 Mobile Safari/537.36
accept: application/json
content-type: application/json
sec-ch-ua: "Not A(Brand";v="8", "Chromium";v="132", "Google Chrome";v="132"
sec-ch-ua-mobile: ?1
sec-ch-ua-platform: "Android"

plz, plz, plz, ty.