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Connect to MongoDB Data in JRuby

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

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

Configure a JDBC Connection to MongoDB 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 MongoDB\lib).

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

Set the Server, Database, User, and Password connection properties to connect to MongoDB. To access MongoDB collections as tables you can use automatic schema discovery or write your own schema definitions. Schemas are defined in .rsd files, which have a simple format. You can also execute free-form queries that are not tied to the schema.

Built-in Connection String Designer

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

java -jar cdata.jdbc.mongodb.jar

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

Below is a typical JDBC connection string for MongoDB:

jdbc:mongodb:Server=MyServer;Port=27017;Database=test;User=test;Password=Password;

Create a JRuby App with Connectivity to MongoDB Data

Create a new Ruby file (for example: MongoDBSelect.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 MongoDB 2018/lib/cdata.jdbc.mongodb.jar' url = "jdbc:mongodb:Server=MyServer;Port=27017;Database=test;User=test;Password=Password;" conn = java.sql.DriverManager.getConnection(url) stmt = conn.createStatement rs = stmt.executeQuery("SELECT borough, cuisine FROM restaurants") while (rs.next) do puts rs.getString(1) + ' ' + rs.getString(2) end

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

jruby -S MongoDBSelect.rb

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