custom_json.go

package main

import (
	"encoding/json"
	"fmt"
)

type BinaryInt int

func (b BinaryInt) MarshalJSON() ([]byte, error) {
	return []byte(fmt.Sprintf("\"%b\"", b)), nil
}

type Home struct {
	Number   int
	District string
}

type Person struct {
	Name string
	Age  int
	Home Home
}

type MyHome struct {
	*Home
	Number BinaryInt
}
type MyPerson struct {
	*Person
	Age  BinaryInt
	Home MyHome
}

func Encode(p *Person) ([]byte, error) {
	mypersion := MyPerson{
		Person: p,
		Age:    BinaryInt(p.Age),
		Home: MyHome{
			Home:   &p.Home,
			Number: BinaryInt(p.Home.Number),
		},
	}
	return json.Marshal(mypersion)
}

func main() {
	p := Person{
		Name: "John",
		Age:  30,
		Home: Home{
			Number:   123,
			District: "Sofia",
		},
	}
	buf, _ := Encode(&p)
	fmt.Println(string(buf))
}