Golang bytearray hex json representation, Playground: https://play.golang.org/p/fO7lmZ5WjWq

hexByteArray.go

package main

import (
	"encoding/hex"
	"encoding/json"
	"fmt"
	"os"
)

// JSN has some struct for json
type JSN struct {
	Bytes ByteString `json:"bytes"`
	Name  string     `json:"name"`
}

// ByteString is a byte array that serializes to hex
type ByteString []byte

// MarshalJSON serializes ByteArray to hex
func (s ByteString) MarshalJSON() ([]byte, error) {
	bytes, err := json.Marshal(fmt.Sprintf("%x", string(s)))
	return bytes, err
}

// UnmarshalJSON deserializes ByteArray to hex
func (s *ByteString) UnmarshalJSON(data []byte) error {
	var x string
	err := json.Unmarshal(data, &x)
	if err == nil {
		str, e := hex.DecodeString(x)
		*s = ByteString([]byte(str))
		err = e
	}

	return err

}

func main() {
	j := JSN{[]byte("test"), "Michael"}
	marshaledJ := toJSON(j)

	fmt.Printf("json is %s\n\n", marshaledJ)

	unmarshaledJ := JSN{}
	json.Unmarshal([]byte(marshaledJ), &unmarshaledJ)
	fmt.Printf("Deserialized: bArray: %s name: %s\n",
		string(unmarshaledJ.Bytes), unmarshaledJ.Name)
}

func toJSON(p interface{}) string {
	bytes, err := json.Marshal(p)
	if err != nil {
		fmt.Println(err.Error())
		os.Exit(1)
	}

	return string(bytes)
}