// Copyright 2025 Google LLC

//

// Licensed under the Apache License, Version 2.0 (the "License");

// you may not use this file except in compliance with the License.

// You may obtain a copy of the License at

//

// http://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing, software

// distributed under the License is distributed on an "AS IS" BASIS,

// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

// See the License for the specific language governing permissions and

// limitations under the License.

// sample-metadata:

// title: Performs a read-write transaction with isolation level option

// usage: node repeatable-reads.js <INSTANCE_ID> <DATABASE_ID> <PROJECT_ID>

'use strict';

function main(

instanceId = 'my-instance',

databaseId = 'my-database',

projectId = 'my-project-id',

) {

// [START spanner_isolation_level]

// Imports the Google Cloud Spanner client library

const {Spanner, protos} = require('@google-cloud/spanner');

// The isolation level specified at the client-level will be applied

// to all RW transactions.

const defaultTransactionOptions = {

isolationLevel:

protos.google.spanner.v1.TransactionOptions.IsolationLevel.SERIALIZABLE,

};

// Instantiates a client with defaultTransactionOptions

const spanner = new Spanner({

projectId: projectId,

defaultTransactionOptions,

});

function runTransactionWithIsolationLevel() {

// Gets a reference to a Cloud Spanner instance and database

const instance = spanner.instance(instanceId);

const database = instance.database(databaseId);

// The isolation level specified at the request level takes precedence over the isolation level configured at the client level.

const isolationOptionsForTransaction = {

isolationLevel:

protos.google.spanner.v1.TransactionOptions.IsolationLevel

.REPEATABLE_READ,

};

database.runTransaction(

isolationOptionsForTransaction,

async (err, transaction) => {

if (err) {

console.error(err);

return;

}

try {

const query =

'SELECT AlbumTitle FROM Albums WHERE SingerId = 1 AND AlbumId = 1';

const results = await transaction.run(query);

// Gets first album's title

const rows = results[0].map(row => row.toJSON());

const albumTitle = rows[0].AlbumTitle;

console.log(`previous album title ${albumTitle}`);

const update =

"UPDATE Albums SET AlbumTitle = 'New Album Title' WHERE SingerId = 1 AND AlbumId = 1";

const [rowCount] = await transaction.runUpdate(update);

console.log(

`Successfully updated ${rowCount} record in Albums table.`,

);

await transaction.commit();

console.log(

'Successfully executed read-write transaction with isolationLevel option.',

);

} catch (err) {

console.error('ERROR:', err);

transaction.end();

} finally {

// Close the database when finished.

await database.close();

}

},

);

}

runTransactionWithIsolationLevel();

// [END spanner_isolation_level]

}

process.on('unhandledRejection', err => {

console.error(err.message);

process.exitCode = 1;

});

main(...process.argv.slice(2));