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