Connect to PostgreSQL Data in JRuby

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PostgreSQL JDBC Driver

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Create a simple JRuby app with access to live PostgreSQL data.

JRuby is a high-performance, stable, fully threaded Java implementation of the Ruby programming language. The CData JDBC Driver for PostgreSQL makes it easy to integrate connectivity to live PostgreSQL data in JRuby. This article shows how to create a simple JRuby app that connects to PostgreSQL data, executes a query, and displays the results.

Configure a JDBC Connection to PostgreSQL Data

Before creating the app, note the installation location for the JAR file for the JDBC Driver (typically C:\Program Files\CData\CData JDBC Driver for PostgreSQL\lib).

JRuby natively supports JDBC, so you can easily connect to PostgreSQL and execute SQL queries. Initialize the JDBC connection with the getConnection function of the java.sql.DriverManager class.

To connect to PostgreSQL, set the Server, Port (the default port is 5432), and Database connection properties and set the User and Password you wish to use to authenticate to the server. If the Database property is not specified, the data provider connects to the user's default database.

Built-in Connection String Designer

For assistance in constructing the JDBC URL, use the connection string designer built into the PostgreSQL JDBC Driver. Either double-click the JAR file or execute the jar file from the command-line.

java -jar cdata.jdbc.postgresql.jar

Fill in the connection properties and copy the connection string to the clipboard.

Below is a typical JDBC connection string for PostgreSQL:

jdbc:postgresql:User=postgres;Password=admin;Database=postgres;Server=127.0.0.1;Port=5432;

Create a JRuby App with Connectivity to PostgreSQL Data

Create a new Ruby file (for example: PostgreSQLSelect.rb) and open it in a text editor. Copy the following code into your file:

require 'java' require 'rubygems' require 'C:/Program Files/CData/CData JDBC Driver for PostgreSQL 2018/lib/cdata.jdbc.postgresql.jar' url = "jdbc:postgresql:User=postgres;Password=admin;Database=postgres;Server=127.0.0.1;Port=5432;" conn = java.sql.DriverManager.getConnection(url) stmt = conn.createStatement rs = stmt.executeQuery("SELECT ShipName, ShipCity FROM Orders") while (rs.next) do puts rs.getString(1) + ' ' + rs.getString(2) end

With the file completed, you are ready to display your PostgreSQL data with JRuby. To do so, simply run your file from the command line:

jruby -S PostgreSQLSelect.rb

Writing SQL-92 queries to PostgreSQL allows you to quickly and easily incorporate PostgreSQL data into your own JRuby applications. Download a free trial today!