Ask for Help

"Has anyone implemented mutli-table (class table) inheritance in Rails, as apposed to single table inheritance (STI)?"

• There are some plugins that nobody has tried, such as inherits_from
• What about a view to represent the super set of tables and rows?

"We're looking for a dead-simple, drop-in JS rating or 'starting' plugin."

Check out the start-rating jQuery plugin. Any other suggestions?

At Pivotal, we are passionate about test driven development, keeping things DRY, and writing readable and understandable code. Satisfying all of these desires can be challenging, especially when writing test code. In particular, ActiveRecord extensions present several challenges: which models using an extension should we test? How do we both test our extension in isolation while also testing all model's usage of that extension? Is it even worth it?

The answer is yes, it is worth it, and it's also fairly easy, readable, understandable, and DRY. I will present both a common problem and a solution, using a cumulation of technologies and techniques from multiple Pivotal projects, in particular using acts_as_fu to create laser-targeted, isolated, and disposable ActiveRecord models for testing extensions and RSpec shared behaviors to minimize the amount of duplicated test code.

Interesting Things

• application.rb vs. application_controller.rb: As we all know, ApplicationController breaks with Rails convention and lives in the application.rb file, not application_controller.rb. Be careful if you create an application_controller.rb file of your own, as this can confuse Rails class loading and might result in Rails deciding not to load application.rb.

• Google Webmaster Tools: Note that if you are using Google Webmaster Tools that statistics are different for www.example.com and example.com (sans www).

• Nested Model Forms are coming in Rails 2.3! There is even a patch in progress.

• One team discovered a jaw-dropping issue with has_many :through. Given the following:

  class User < ActiveRecord::Base
    has_many :user_photos
    has_many :photos, :through => :user_photos
  

  • a_user.photos.create will create and persist both a Photo object and the UserPhoto join object
  • photo = a_user.photos.build followed by photo.save will create and persist the Photo object only, and will not persist an appropriate UserPhoto join object.

• Rails 2.2: Test::Unit::TestCase extentions have been removed from Rails Core and are now in ActiveSupport::TestCase. As stated in the Groups Thread about this, use ActiveSupport::TestCase instead of Test::Unit::TestCase in test/test_helper.rb.

Interesting Things

• Teaser: Selenium for Flash! We've developed a Selenium-like framework for Flash. It's pre-alpha, and needs to be extracted from it's current home inside a project. Are you interested in a Selenium-like framework for Flash, or have you written one yourself? Let us know!

• STI-weirdness. Rails surprise of the day: given a query of a has_many :photos where Photos has STI subclasses (got that?) Rails will build a SQL query that includes the subclass types of Photo, which you might not want:

  foo.photos.find_by_type("Photo") 
  # query will have "... WHERE type IN ('Photo', 'OriginalPhoto', 'ThumbnailPhoto')"
  

• It appears that the retardase_inhibitor might not work with Rails 2.1.X due to fixes in ActionMailer.

• JetBrains has been hard at work: they have released both a new Ruby plugin for IntelliJ, and a ruby-specific IDE (based on IntelliJ) named RubyMine.

• Check out Pivot Jonathan's wife's art exhibit at Artist-Xchange Gallery in San Francisco, Friday 11/7 from 7-10pm:

  
  3169 16th Street
  San Francisco
  CA 94103
  

Ask for Help

"I want to create a custom launcher for Firefox 2 and Firefox 3 with different profiles. Perhaps the real question is how do we create a custom version of a Mac application launcher, passing in the arguments we need?"

... without having to invoke it on the command line every time.

"We're trying to delete cookies in our Controller, but they keep appearing in the headers anyway."

Suggestion: make sure you are specifying your URL paths and domains correctly.

"Why won't our CSS and other assets load the first time when accessing an SSL-protected domain on Engine Yard?"

It's most likely not Engine Yard or Firefox 3's fault. More research needed.

• Where am I? -- Ever need to find the name of the method you are currently within? Here's a this_method method! The magic is in the REGEX, of course.

module Kernel
  private
  def this_method
    caller[0] =~ /`([^']*)'/ and $1
  end
end

• One project wanted to test a very ActiveRecord-specific Module in an isolated, generic way. After spending time researching techniques of mocking and stubbing the many, many ActiveRecord methods that would be touched, they decided to just dynamically create an ActiveRecord and a DB Table for it on the fly! They even used single table inheritance (STI)

  describe "MyMagicModule Mixin" do
    before(:all) do
      ActiveRecord::Base.connection.create_table "some_base_models",
                                                   :force => true do |t|
        t.string   "name"
        t.string   "type"
        t.integer  "some_model_b_id", :limit => 11
      end
    end

    after(:all) do
      ActiveRecord::Base.connection.drop_table "some_base_models"
    end


    class SomeBaseModel < ActiveRecord::Base;end

    class SomeModelA < SomeBaseModel
      include MyMagicModule

      belongs_to: :some_model_b
    end

    class SomeModelB < SomeBaseModel
      include MyMagicModule
    end

    it 'should use special belongs_to stuff from MyMagicModule' do
       model_a = SomeModelA.create!(
                        :name=> "Model A",
                        :some_model_be => SomeModelB.create!(:name => "Model B"))
       # test the functionality from MyMagicModule
    end
  end