Gist to reproduce the CreatedAt behaviour in Gorm library (GO)

main.go

package main

import (
	"encoding/json"
	"errors"
	"time"

	_ "github.com/go-sql-driver/mysql"
	"github.com/jinzhu/gorm"
)

var db gorm.DB

func init() {
	var err error

	db, err = gorm.Open("mysql", "root:@/embrace?charset=utf8&parseTime=True")
	if err != nil {
		panic(err)
	}

	db.LogMode(true)
}

func main() {
	db.SingularTable(true)

	//create the user
	var user = User{ID: 1, FirstName: "Alessio", LastName: "Cavaleri"}
	if err := user.Create(); err != nil {
		panic(err)
	}

	//simulate a json string received and consumed by an API
	var updatedUserJSON = `{"id":1, "firstName" : "Alessio2", "lastName" : "Cavaleri2"}`
	var updatedUser User
	json.Unmarshal([]byte(updatedUserJSON), &updatedUser)

	//update the user
	if err := updatedUser.Update(); err != nil {
		panic(err)
	}
}

//User defines a user
type User struct {
	ID        int64     `json:"id"`
	FirstName string    `json:"firstName"`
	LastName  string    `json:"lastName"`
	CreatedAt time.Time `json:"createdAt"`
	UpdatedAt time.Time `json:"updatedAt"`
}

//Create create a new user
func (u *User) Create() error {
	db.NewRecord(*u)
	return db.Create(u).Error
}

//Update update a user in DB
func (u *User) Update() error {
	if u.ID <= 0 {
		return errors.New("Cannot update a user without ID")
	}
	return db.Save(u).Error
}


/*

(/Users/alessiocavaleri/Documents/Code/go/src/github.com/alecha/gorm-created/main.go:57) 
[2015-11-19 10:02:44]  [0.76ms]  INSERT INTO `user` (`first_name`,`last_name`,`created_at`,`updated_at`,`id`) VALUES ('Alessio','Cavaleri','2015-11-19T10:02:44+01:00','2015-11-19T10:02:44+01:00','1') 

(/Users/alessiocavaleri/Documents/Code/go/src/github.com/alecha/gorm-created/main.go:65) 
[2015-11-19 10:02:44]  [1.59ms]  UPDATE `user` SET `updated_at` = '2015-11-19T10:02:44+01:00', `first_name` = 'Alessio2', `last_name` = 'Cavaleri2', `created_at` = '0001-01-01T00:00:00Z'  WHERE (`id` = '1')
  
*/