gistfile1.go

package main

import "fmt"

import "encoding/json"

type My struct {
	Name string
}

func (m My) MarshalJSON() ([]byte, error) {
	return json.Marshal(m.Name + "Asdf")
}

func main() {
	t := My{"Angel"}
	j, err := json.Marshal(t)
	fmt.Println(err, string(j))
}