Firestoreの設計ミスをCloudFuntionsとGoスクリプトで解消する

db.collection("users").get()

import * as functions from 'firebase-functions';
import * as admin from 'firebase-admin';

const serviceAccount = require("../xxxxx.json");
admin.initializeApp({
  credential: admin.credential.cert(serviceAccount),
  databaseURL: "https://xxxxxxx.firebaseio.com"
});

export const SyncSongsToUsers = functions.firestore
  .document('users/{userId}/songs/{songId}')
  .onWrite(async (change: any, context: any) => {
    const uid = context.params.userId;
    const newVal = change.after.data();
    const updatedAt = newVal.updatedAt;

    const queryUser = admin.firestore().collection(`users`).doc(uid);
    try {
        const doc = await queryUser.get();
      if (doc.exists) {
        await queryUser.update({
          updatedAt: updatedAt.toDate()
        });
      } else {
        await queryUser.set({
          createdAt: updatedAt.toDate(),
          updatedAt: updatedAt.toDate(),
          deletedAt: null
        });
      }
    } catch(e) {
      console.log("ERROR Set or Update =====>", e);
    }

    return null
  });

func main() {
	ctx := context.Background()
	firestoreClient, err := connectFirestore(ctx)
	if err != nil {
		fmt.Println("firebase Connection error: ", err)
	}
	defer firestoreClient.Close()

	it := firestoreClient.CollectionGroup("songs").Documents(ctx)
	for {
		doc, err := it.Next()
		if err == iterator.Done {
			break
		}
		if err != nil {
            fmt.Println("err\n", err)
		}
		song := &Song{}
		err = doc.DataTo(song)
		if err != nil {
			return
		}
		doc.Ref.Set(ctx, map[string]interface{}{
			"folderId": xxxx,
		}, firestore.MergeAll)
	}
	fmt.Println("----- main end -----")
}

func connectFirestore(ctx context.Context) (*firestore.Client, error) {
	sa := option.WithCredentialsFile("../xxxxx.json")
	app, err := firebase.NewApp(ctx, nil, sa)
	if err != nil {
		fmt.Printf("error initializing app: %v", err)
		return nil, err
	}
	return app.Firestore(ctx)
}

func main() {
	ctx := context.Background()
	firestoreClient, err := connectFirestore(ctx)
	if err != nil {
		fmt.Println("firebase Connection error: ", err)
	}
	defer firestoreClient.Close()

	iter := firestoreClient.Collection("users").Documents(ctx)
	for {
		doc, err := iter.Next()
		if err == iterator.Done {
			break
		}
		if err != nil {
			fmt.Println("err\n", err)
		}
		it := doc.Ref.Collection("folders").Documents(ctx)
		flg := true
		for {
			folderDoc, err := it.Next()
			if err == iterator.Done {
				break
			}
			if doc.Data() != nil {
				flg = false
			}
		}
		if flg == true {
			uid := doc.Ref.ID
			now := time.Now()
			_, _, err = firestoreClient.
				Collection("users").
				Doc(uid).
				Collection("folders").
				Add(ctx, map[string]interface{}{
                    "name":          "未分類",
                    ・
                    ・
					"createdAt":     now,
					"updatedAt":     now,
					"deletedAt":     nil,
				})
			if err != nil {
				fmt.Println("err\n", err)
			}
		}
	}
	fmt.Println("----- main end -----")
}

func connectFirestore(ctx context.Context) (*firestore.Client, error) {
	sa := option.WithCredentialsFile("../xxxxx.json")
	app, err := firebase.NewApp(ctx, nil, sa)
	if err != nil {
		fmt.Printf("error initializing app: %v", err)
		return nil, err
	}
	return app.Firestore(ctx)
}