Project: YugabyteDB (App Definition and Development / Database)
File: cloud-ysql-node.md

title: Build a Node.js application that uses YSQL headerTitle: Build a Node.js application description: Build a simple Node.js application using the driver and using the YSQL API to connect to and interact with a YugabyteDB Managed cluster. headContent: "Client driver: node-postgres" menu: v2.18: parent: build-apps name: Node.js identifier: cloud-node weight: 400 type: docs The following tutorial shows a small that connects to a YugabyteDB cluster using the and performs basic SQL operations. Use the application as a template to get started with YugabyteDB Managed in Node.js. The latest version of . Clone the sample application to your computer: ```sh git clone https://github.com/YugabyteDB-Samples/yugabyte-simple-node-app.git && cd yugabyte-simple-node-app ``` If your cluster is running on YugabyteDB Managed, you need to modify the connection parameters so that the application can establish a connection to the YugabyteDB cluster. (You can skip this step if your cluster is running locally and listening on 127.0.0.1:5433.) To do this: Open the `sample-app.js` file. Set the following configuration parameter constants: host - the host name of your YugabyteDB cluster. For local clusters, use the default (127.0.0.1). For YugabyteDB Managed, select your cluster on the Clusters page, and click Settings. The host is displayed under Connection Parameters. port - the port number for the driver to use (the default YugabyteDB YSQL port is 5433). database - the name of the database you are connecting to (the default is `yugabyte`). user and password - the username and password for the YugabyteDB database. For local clusters, use the defaults (`yugabyte` and `yugabyte`). For YugabyteDB Managed, use the credentials in the credentials file you downloaded. ssl - YugabyteDB Managed . To enable `verify-ca` SSL mode, the `rejectUnauthorized` property is set to `true` to require root certificate chain validation; replace `pathtoyourrootcertificate` with the full path to the YugabyteDB Managed cluster CA certificate. Save the file. Install the node-postgres module. ```sh npm install pg ``` Install the utility: ```sh npm install --save async ``` Start the application. ```sh $ node

``` You should see output similar to the following: ```output >>> Successfully connected to YugabyteDB! >>> Successfully created table DemoAccount. >>> Selecting accounts: name = Jessica, age = 28, country = USA, balance = 10000 name = John, age = 28, country = Canada, balance = 9000 >>> Transferred 800 between accounts. >>> Selecting accounts: name = Jessica, age = 28, country = USA, balance = 9200 name = John, age = 28, country = Canada, balance = 9800 ``` You have successfully executed a basic Node.js application that works with YugabyteDB Managed. Open the `sample-app.js` file in the `yugabyte-simple-node-app` folder to review the methods. The `connect` method establishes a connection with your cluster via the node-postgres driver. ```js try { client = new pg.Client(config); await client.connect(); console.log('>>>> Connected to YugabyteDB!'); callbackHadler(); } catch (err) { callbackHadler(err); } ``` The `createDatabase` method uses PostgreSQL-compliant DDL commands to create a sample database. ```js try { var stmt = 'DROP TABLE IF EXISTS DemoAccount'; await client.query(stmt); stmt = `CREATE TABLE DemoAccount ( id int PRIMARY KEY, name varchar, age int, country varchar, balance int)`; await client.query(stmt); stmt = `INSERT INTO DemoAccount VALUES (1, 'Jessica', 28, 'USA', 10000), (2, 'John', 28, 'Canada', 9000)`; await client.query(stmt); console.log('>>>> Successfully created table DemoAccount.'); callbackHadler(); } catch (err) { callbackHadler(err); } ``` The `selectAccounts` method queries your distributed data using the SQL `SELECT` statement. ```js try { const res = await client.query('SELECT name, age, country, balance FROM DemoAccount'); var row; for (i = 0; i < res.rows.length; i++) { row = res.rows[i]; console.log('name = %s, age = %d, country = %s, balance = %d', row.name, row.age, row.country, row.balance); } callbackHadler(); } catch (err) { callbackHadler(err); } ``` The `transferMoneyBetweenAccounts` method updates your data consistently with distributed transactions. ```js try { await client.query('BEGIN TRANSACTION'); await client.query('UPDATE DemoAccount SET balance = balance - ' + amount + ' WHERE name = \'Jessica\''); await client.query('UPDATE DemoAccount SET balance = balance + ' + amount + ' WHERE name = \'John\''); await client.query('COMMIT'); console.log('>>>> Transferred %d between accounts.', amount); callbackHadler(); } catch (err) { callbackHadler(err); } ```