Go: Cloud Firestore のデータを更新 (Update)

firestore_update.go

// ---------------------------------------------------------------
//
//	firestore_update.go
//
//					Dec/16/2020
//
// ---------------------------------------------------------------
package main
 
import (
	"context"
	"fmt"
	"log"
	"os"
	"strconv"
	"time"
 
	firebase "firebase.google.com/go"
	"google.golang.org/api/option"
)
 
// ---------------------------------------------------------------
func get_current_date_proc () string {
	now := time.Now ()
	fmt.Printf ("%s\t" ,now)
	fmt.Printf ("%d-%d-%d\n" ,now.Year (),now.Month(),now.Day())
	today := strconv.Itoa (now.Year()) + "-" +
		fmt.Sprintf ("%d",now.Month()) + "-" +
		strconv.Itoa (now.Day())

	return	today
}

// ---------------------------------------------------------------
func main() {
	fmt.Fprintf (os.Stderr,"*** 開始 ***\n")
	key_in := os.Args[1]
	population_in,_ := strconv.Atoi (os.Args[2])
	fmt.Printf ("key_in = %s\t" , key_in)
	fmt.Printf ("population_in = %d\n" , population_in)
	// 初期化
	ctx := context.Background()
	sa := option.WithCredentialsFile("./application_default_credentials.json")
	app, err := firebase.NewApp(ctx, nil, sa)
	if err != nil {
		log.Fatalln(err)
	}
 
	client, err := app.Firestore(ctx)
	if err != nil {
		log.Fatalln(err)
	}

dsnap, err := client.Collection("cities").Doc(key_in).Get(ctx)
if err != nil {
        log.Fatalf("Failed : %v", err)
}

mm := dsnap.Data()
fmt.Printf("Document data: %#v\n", mm)

name_aa := dsnap.Data()["name"]

today := get_current_date_proc ()


 _, err = client.Collection("cities").Doc(key_in).Set(ctx, map[string]interface{}{
	"name":  name_aa,
	"population": population_in,
	"date_mod": today,
    })
    if err != nil {
        log.Fatalf("Failed adding alovelace: %v", err)
    }

	// 切断
	defer client.Close()

	fmt.Fprintf (os.Stderr,"*** 終了 ***\n")
}

// ---------------------------------------------------------------

実行コマンド

project_id="project-dec16-2020"
echo $project_id
export GOOGLE_CLOUD_PROJECT=$project_id
#
go run firestore_update.go t0926 5134900