Build a Ruby application that uses YSQL

The following tutorial shows a small Ruby application that connects to a YugabyteDB cluster using the Ruby Pg driver and performs basic SQL operations. Use the application as a template to get started with YugabyteDB Aeon in Ruby.

Prerequisites

• Ruby 3.1 or later.

• OpenSSL 1.1.1 or later (used by libpq and pg to establish secure SSL connections).

• libpq. Homebrew users on macOS can install using brew install libpq. You can download the PostgreSQL binaries and source from PostgreSQL Downloads.

• Ruby pg. To install Ruby pg, run the following command:

  shCopy

  gem install pg -- --with-pg-include=<path-to-libpq>/libpq/include --with-pg-lib=<path-to-libpq>/libpq/lib
  

  Replace <path-to-libpq> with the path to the libpq installation; for example, /usr/local/opt.

Clone the application from GitHub

Clone the sample application to your computer:

git clone https://github.com/YugabyteDB-Samples/yugabyte-simple-ruby-app.git && cd yugabyte-simple-ruby-app

Provide connection parameters

If your cluster is running on YugabyteDB Aeon, 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:

1. Open the sample-app.rb file.

2. Set the following configuration-related parameters:

   • host - the host name of your YugabyteDB cluster. For local clusters, use the default (127.0.0.1). For YugabyteDB Aeon, 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).
   • dbname - 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 Aeon, use the credentials in the credentials file you downloaded.
   • sslmode - the SSL mode to use. YugabyteDB Aeon requires SSL connections; use verify-full.
   • sslrootcert - the full path to the YugabyteDB Aeon cluster CA certificate.

3. Save the file.

Build and run the application

Make the application file executable.

chmod +x sample-app.rb

Run the application.

$ ./sample-app.rb

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 Ruby application that works with YugabyteDB Aeon.

Explore the application logic

Open the sample-app.rb file in the yugabyte-simple-ruby-app folder to review the methods.

connect

The connect method establishes a connection with your cluster via the libpqxx driver.

conn = PG.connect(
    host: '',
    port: '5433',
    dbname: 'yugabyte',
    user: '',
    password: '',
    sslmode: 'verify-full',
    sslrootcert: ''
    );

create_database

The create_database method uses PostgreSQL-compliant DDL commands to create a sample database.

conn.exec("DROP TABLE IF EXISTS DemoAccount");

conn.exec("CREATE TABLE DemoAccount ( \
            id int PRIMARY KEY, \
            name varchar, \
            age int, \
            country varchar, \
            balance int)");

conn.exec("INSERT INTO DemoAccount VALUES \
            (1, 'Jessica', 28, 'USA', 10000), \
            (2, 'John', 28, 'Canada', 9000)");

select_accounts

The select_accounts method queries your distributed data using the SQL SELECT statement.

begin
    puts ">>>> Selecting accounts:\n";

    rs = conn.exec("SELECT name, age, country, balance FROM DemoAccount");

    rs.each do |row|
        puts "name=%s, age=%s, country=%s, balance=%s\n" % [row['name'], row['age'], row['country'], row['balance']];
    end

ensure
    rs.clear if rs
end

transfer_money_between_accounts

The transferMoneyBetweenAccounts method updates your data consistently with distributed transactions.

begin
    conn.transaction do |txn|
        txn.exec_params("UPDATE DemoAccount SET balance = balance - $1 WHERE name = \'Jessica\'", [amount]);
        txn.exec_params("UPDATE DemoAccount SET balance = balance + $1 WHERE name = \'John\'", [amount]);
    end

    puts ">>>> Transferred %s between accounts.\n" % [amount];

rescue PG::TRSerializationFailure => e
    puts "The operation is aborted due to a concurrent transaction that is modifying the same set of rows. \
            Consider adding retry logic for production-grade applications.";
    raise
end

Learn more

Ruby pg driver

libpq driver