Golang API（与Buffalo）检索发布数据

I am developing an API in Golang (with Buffalo library).

I have my route set to point to :

func (ur UserResource) Create(c buffalo.Context) error {
    // new User
    u := &models.User{}
    if err := c.Bind(u); err != nil {
        return c.Render(500, r.String(err.Error()))
    }
    id, _ := uuid.NewV4()
    u.ID = id
    db[u.ID] = *u
    return c.Render(201, r.JSON(u))
}

The problem is that when I test my api I have the following error :

(and my header Content-Type is set to multipart/form-data)

If I change the way values are passed to form-url-encoded and set no header, I have this error : invalid character 'i' in literal false (expecting 'a')