JSON unmarshalJson Timestamp to ISO Date

main.go

package main

import (
	"encoding/json"
	"fmt"
	"strconv"
	"time"
)

type CustomTime struct {
	Time time.Time
}

const ctLayout = "2006-01-02T15:04:05Z0700"

func (ct *CustomTime) UnmarshalJSON(b []byte) (err error) {

	s := string(b)
	i, err := strconv.ParseInt(s, 10, 64)
	if err != nil {
		panic(err)
	}
	tm := time.Unix(i, 0)

	ct.Time = tm

	return nil
}

type User struct {
	Time CustomTime `json:"Time"`
}

func main() {
	var b = User{}
	var data = `{"Time":1579008351}`
	json.Unmarshal([]byte(data), &b)
	fmt.Printf("%v", b)
}