appengine/datastore と cloud/datastore の timezone に関する挙動を確認する

datastore_comparison.go

package main

import (
	"context"
	"fmt"
	"net/http"
	"time"

	cldatastore "cloud.google.com/go/datastore"
	"google.golang.org/appengine"
	aedatastore "google.golang.org/appengine/datastore"
	"google.golang.org/appengine/log"
)

type User struct {
	Name string
	CreatedAt time.Time
}

var jstLoc *time.Location
var pstLoc *time.Location

func init() {
	var err error
	jstLoc, err = time.LoadLocation("Asia/Tokyo")
	if err != nil {
		panic(err)
	}
	pstLoc, err = time.LoadLocation("America/Dawson")
	if err != nil {
		panic(err)
	}
}

func main() {
	http.HandleFunc("/appengine", hookError(func(ctx context.Context) ([]string, error) {
		var outputs []string

		k := aedatastore.NewKey(ctx, "User", "id-appengine", 0, nil)
		put := &User{
			Name:      "appengine",
			CreatedAt: time.Date(2020, 1, 2, 1, 2, 3, 0, jstLoc),
		}
		if _, err := aedatastore.Put(ctx, k, put); err != nil {
			return nil, err
		}
		got := new(User)
		if err := aedatastore.Get(ctx, k, got); err != nil {
			return nil, err
		}
		outputs = append(outputs, fmt.Sprintf("put: %+v, loc: %#v", put, put.CreatedAt.Location()))
		outputs = append(outputs, fmt.Sprintf("got: %+v, loc: %#v", got, got.CreatedAt.Location()))
		return outputs,nil
	}))

	http.HandleFunc("/cloud", hookError(func(ctx context.Context) ([]string, error) {
		var outputs []string
		client, err := cldatastore.NewClient(ctx, cldatastore.DetectProjectID)
		if err != nil {
			return nil, err
		}
		defer func(){
			client.Close()
		}()
		k := cldatastore.NameKey("User", "id-cloud", nil)
		put := &User{
			Name:      "cloud",
			CreatedAt: time.Date(2020, 1, 2, 1, 2, 3, 0, pstLoc),
		}
		if _, err := client.Put(ctx, k, put); err != nil {
			return nil, err
		}
		got := new(User)
		if err := client.Get(ctx, k, got); err != nil {
			return nil, err
		}
		outputs = append(outputs, fmt.Sprintf("put: %+v, loc: %#v", put, put.CreatedAt.Location()))
		outputs = append(outputs, fmt.Sprintf("got: %+v, loc: %#v", got, got.CreatedAt.Location()))
		return outputs, nil
	}))
	appengine.Main()
}

func hookError(f func (ctx context.Context) ([]string, error)) func(http.ResponseWriter, *http.Request) {
	return func(w http.ResponseWriter, r *http.Request) {
		ctx := appengine.NewContext(r)
		outputs, err := f(ctx)
		if err != nil {
			log.Errorf(ctx, "error: %+v", err)
			http.Error(w, err.Error(), 500)
			return
		}
		w.Header().Set("Content-Type", "text/plain; charset=utf-8")
		for _, o:= range outputs {
			fmt.Fprintf(w, "%s\n", o)
		}
	}
}

datastore console 上の表示

PC のタイムゾーンをウランバートル標準時に変えてから再度 datastore console を表示した結果