GoLang CustomTime format with json Unmarshal and Marshal operations

main.go

package main

import (
	"encoding/json"
	"fmt"
	"log"
	"strings"
	"time"
)

type StructWithCustomTime struct {
	MyTime CustomTime `json:"my_time"`
}

type CustomTime struct {
	time.Time
}

const localTimeLayout = "2006-01-02 15:04"

func (ct *CustomTime) UnmarshalJSON(b []byte) (err error) {
	s := strings.Trim(string(b), "\"")
	if s == "null" {
		ct.Time = time.Time{}
		return
	}
	ct.Time, err = time.Parse(localTimeLayout, s)
	return
}

func (ct CustomTime) MarshalJSON() ([]byte, error) {
	stamp := fmt.Sprintf("\"%s\"", ct.Time.Format(localTimeLayout))
	return []byte(stamp), nil
}

func main() {
	incomingJson := `{"my_time":"2020-01-01 12:00"}`

	var s StructWithCustomTime

	// Unmarshal the incoming JSON into a StructWithCustomTime
	err := json.Unmarshal([]byte(incomingJson), &s)
	if err != nil {
		log.Printf("Error unmarshalling JSON: %v", err)
	}

	// Marshal the StructWithCustomTime back into JSON
	outgoingJson, err := json.Marshal(s)
	if err != nil {
		log.Printf("Error marshalling JSON: %v", err)
	}

	fmt.Println(string(outgoingJson))
}