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JRuby: Calling Ruby’s ActiveRecord from Java Using the Bean Scripting Framework

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JRuby: Calling Ruby’s ActiveRecord from Java Using the Bean Scripting FrameworkHere we need to use the Bean Scripting Framework (BSF) since Java 5 doesn’t have the built-in scripting support that Java 6 has. I will also use 2 helper classes (JRubyHelper.java and BSFHelper.java) provided by ociweb.com. For brevity I will leave out the source of the helper classes and concentrate on the actual code to make a call to a Ruby script from Java:

book_titles

Line 31: initializes an empty ArrayList that will be passed into the Ruby script.

Line 32: declares (or registers) the books by name which can then be referenced
in the Ruby script.

Line 33: actually executes the Ruby script.

Lines 36-40: just looping over the books and printing the titles.

Here I’ve created an arjava directory under the Rails plugins directory:

arjava_dir

book_titles.rb is the script called from Java:

book_titles


models.rb defines the book Ruby object and extends ActiveRecord::base

models

query.rb is just a script to test the models.rb dependency.

query
For simplicity and just to prove the call to Ruby’s ActiveRecord will work from Java, I setup an Ant target to test it:

ant_arjava

That’s it for now. For a good write-up on ActiveRecord, Bruce Tate wrote an article on developerWorks: “Crossing borders: Exploring ActiveRecord”

Written by Shane

July 25th, 2007 at 11:45 am

Posted in Software Development

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7 Responses to 'JRuby: Calling Ruby’s ActiveRecord from Java Using the Bean Scripting Framework'

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  1. Hi

    is it possible to provide a working example for this article?

    Thanks!

    Jason

    26 Jul 07 at 2:26 pm

  2. I want to ask you about integration JRuby to Idea, without highlighting errors in: require ‘rubygems’

    pftg

    27 Jul 07 at 1:53 am

  3. I’m using the latest version of the IDEA EAP IDE as well as the latest version of the Ruby plugin.

    shane

    27 Jul 07 at 11:22 am

  4. Just tried your code. I had an error with connection to database. After knocking my head on the keyboard I found a mistake in your code (at least for me it was a mistake).
    In the code ActiveRecord::Base.establish_connection … you wrote :user => “root” - well it should be :username => “root”.
    The way I found out the error was - I ran the script and got a error for mysql connection - connection from root@192.168.*.* is forbidden. But I set :user => ‘my_correct_login’. So as :user was not valid option it was just ignored, so “root” was used instead by default.

    Ziggy

    22 Aug 07 at 8:10 am

  5. [...] I found this great blog post that describes using the BSF to call Ruby’s ActiveRecord from [...]

    Follow-up on Ruby On Java Presentation « dambalah

    24 Aug 07 at 7:01 pm

  6. I tried to run this example , but i am getting the following error
    “unable to load language: ruby: org.jruby.exceptions.RaiseException: cannot load Java class JavaLang”

    padmapriya

    6 Aug 08 at 2:22 pm

  7. I tried to run this example as
    1) standalone
    2)Using “ant run-java-ar”

    In both cases i got the same above error
    [java] org.jruby.exceptions.RaiseException: cannot load Java class JavaLang
    [java] unable to load language: ruby: org.jruby.exceptions.RaiseException: cannot load Java class JavaLang

    Please let me know if i need to set anything in the classpath?

    padmapriya

    6 Aug 08 at 2:45 pm

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