Build a Node.js application
The following tutorial shows a small Node.js application that connects to a YugabyteDB cluster using the node-postgres module and performs basic SQL operations. Use the application as a template to get started with YugabyteDB Managed in Node.js.
Prerequisites
The latest version of Node.js.
Clone the application from GitHub
Clone the sample application to your computer:
git clone https://github.com/YugabyteDB-Samples/yugabyte-simple-node-app.git && cd yugabyte-simple-node-app
Provide connection parameters
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
andyugabyte
). For YugabyteDB Managed, use the credentials in the credentials file you downloaded. - ssl - YugabyteDB Managed requires SSL connections. To enable
verify-ca
SSL mode, therejectUnauthorized
property is set totrue
to require root certificate chain validation; replacepath_to_your_root_certificate
with the full path to the YugabyteDB Managed cluster CA certificate.
-
Save the file.
Build and run the application
Install the node-postgres module.
npm install pg
Install the async utility:
npm install --save async
Start the application.
$ node sample-app.js
You should see output similar to the following:
>>>> 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.
Explore the application logic
Open the sample-app.js
file in the yugabyte-simple-node-app
folder to review the methods.
connect
The connect
method establishes a connection with your cluster via the node-postgres driver.
try {
client = new pg.Client(config);
await client.connect();
console.log('>>>> Connected to YugabyteDB!');
callbackHadler();
} catch (err) {
callbackHadler(err);
}
createDatabase
The createDatabase
method uses PostgreSQL-compliant DDL commands to create a sample database.
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);
}
selectAccounts
The selectAccounts
method queries your distributed data using the SQL SELECT
statement.
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);
}
transferMoneyBetweenAccounts
The transferMoneyBetweenAccounts
method updates your data consistently with distributed transactions.
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);
}