How to get the value of interface{} in Go? (Interface conversion: interface{} is Resp, not mapinterface{})

func login() func(c *lmhttp.context, code int, data interface{}) (int, interface{}) {
    return func(c *lmhttp.context, code int, data interface{}) (int, interface{}) {
    map_data := data.(map[string]interface{})
    fmt.print(map_data, map_data["id"])
  }
}

interface conversion: interface {} is loginresp, not map[string]interface {}

func (c *Context) Response(data interface{}) {
    c.result(http.StatusOK, data)
}

json_str, jsonErr := json.Marshal(data)
if json_str != nil {
    fmt.Printf("%v", jsonErr)
}
m := make(map[string]interface{})
err := json.Unmarshal([]byte(json_str), &m)
if err != nil {
    fmt.Println(err)
    fmt.Println("This is ID", m["id"])
}