unmarshal text in go programming language

jsonUnmarshalText.go

package main

import (
	"bytes"
	"encoding/json"
	"errors"
	"fmt"
	"log"
)

var errUnmarshalNilLevel = errors.New("Can't unmarshal a nil *EmpType")

type EmpType int8

const (
	HR EmpType = iota - 1
	Designer
	Coder
	Manager
	CEO
)

func (e EmpType) String() string {
	switch e {
	case HR:
		return "HR"
	case Designer:
		return "Designer"
	case Coder:
		return "Coder"
	case Manager:
		return "Manager"
	case CEO:
		return "CEO"
	default:
		return fmt.Sprintf("LEVEL(%d)", e)
	}
}

func (e *EmpType) unmarshalText(text []byte) bool {
	switch string(text) {
	case "hr", "HR":
		*e = HR
	case "designer", "DESIGNER":
		*e = Designer
	case "coder", "CODER":
		*e = Coder
	case "manager", "MANAGER":
		*e = Manager
	case "CEO":
		*e = CEO
	default:
		return false
	}
	return true
}

func (e *EmpType) UnmarshalText(text []byte) error {

	if e == nil {
		return errUnmarshalNilLevel
	}

	if !e.unmarshalText(text) && !e.unmarshalText(bytes.ToLower(text)) {
		return fmt.Errorf("Unrecognied employee code: %q", text)
	}

	return nil
}

type Employee struct {
	Name string  `json:"name"`
	Code int64   `json:"code"`
	Age  int64   `json:"age"`
	Type EmpType `json:"type"`
}

func main() {
	rawJSON := []byte(`{
		"name": "Manjeet Singh",
		"code": 3213,
		"age": 32,
		"type": "coder"
	}`)

	var emp Employee

	if err := json.Unmarshal(rawJSON, &emp); err != nil {
		panic(err)
	}

	log.Printf("%+v", emp)

}