Go: gorm で PostgreSQL のデータを更新 (Update)

プログラム

フォルダー構造

$ tree -a
.
├── .env
├── config_postgres.go
└── gorm_pg_update.go

gorm_pg_update.go

// ----------------------------------------------------------------
//
//	gorm_pg_update.go
//
//					Mar/03/2023
//
// ----------------------------------------------------------------
package main

import (
	"fmt"
	"os"
	"strconv"
	"time"
	"gorm.io/gorm"
	"gorm.io/driver/postgres"
)

// ----------------------------------------------------------------
func main() {
	fmt.Fprintln (os.Stderr,"*** 開始 ***")
	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)

	host,user,password,data_base := config_postgres_proc()

dsn := "host=" + host + " user=" + user + " password=" + password + " dbname=" + data_base + " port=5432 sslmode=disable TimeZone=Asia/Tokyo"

	db, err := gorm.Open(postgres.Open(dsn), &gorm.Config{})
	if err != nil {
		panic(err)
		}

	today := get_current_date_proc ()

	fmt.Println (today)

	db.Exec("UPDATE cities SET population = ?,date_mod = ? WHERE id = ?", population_in,today,key_in)

	fmt.Fprintln (os.Stderr,"*** 終了 ***")
}

// ----------------------------------------------------------------
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
}

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

.env
config_postgres.go
はこちら
Go: gorm で PostgreSQL のバージョンを表示

実行の準備

go mod init update
go mod tidy

go.mod go.sum が作成される。

実行結果

$ go run gorm_pg_update.go config_postgres.go t3466 48532100
*** 開始 ***
key_in = t3466	population_in = 48532100
2023-03-03 17:38:09.509613607 +0900 JST m=+0.005400168	2023-3-3
2023-3-3
*** 終了 ***