Installing rbx-require-relative (0.0.5) Unfortunately, a fatal error has occurred.
Please report this error to the Bundler issue tracker at https://github.com/carlhuda/
bundler/issues so that we can fix it. Thanks!/Users/sjain/.rvm/rubies/ruby-1.9.2-p290/
lib/ruby/site_ruby/1.9.1/rubygems/ installer.rb:364:in `ensure_required_ruby_version_met':
rbx-require-relative requires Ruby version ~> 1.8.7. (Gem::InstallError)

This most likely happens because you are declaring a dependency on ruby-debug gem in your Gemfile.

group :development do
  gem 'ruby-debug'
end

With ruby 1.9, you need to update this with new gem name ruby-debug19.

group :development do
  gem 'ruby-debug19'
end

This will eliminate the dependency on rbx-require-relative and fix the issue.

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Not anymore. With this service called “localtunnel”, it is a piece of cake.

http://progrium.com/localtunnel/

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My takeaway:

Mac OS X applies .bash_profile and .profile only for Terminal.app environment and Apple’s technical documentation suggests using ~/.MacOSX/environment.plist for other applications. So, by default PATH value will differ for RubyMine and the console.

For managing the global environments, it also recommends a system preference pane app. This worked for me.

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Here is my take away:

  # returns [class, count] tuples for all active records in the heap 
  def ar_space 
    GC.start 
    h = Hash.new(0) 
    ObjectSpace.each_object do |o| 
      next if o.__id__ == self.__id__ 
      next unless ActiveRecord::Base === o 
      h[o.class.to_s] += 1 
    end 
    return h.sort{|a,b| -(a[1]<=>b[1])} 
  end

Nifty little snippet to fetch number of active record objects on heap. I am guessing, incorporating this as Controller after_filter can help with cost of each request..

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Deploy at Will!

At the first RailsConf I had the pleasure of hearing Martin Fowler deliver an amazing keynote. He made some apt metaphors regarding agile development that I will now paraphrase and mangle.

Imagine you’re tasked with building a computer controlled gun that can accurately hit a target about 50 meters distant. That is the only requirement. One way to do this is to build a complex machine that measures every possible variable (wind, elevation, temperature, etc.) before the shot and then takes aim and shoots. Another approach is to build a simple machine that fires rapidly and can detect where each shot hits. It then uses this information to adjust the aim of the next shot, quickly homing in on the target a little at a time.

The difference between these two approaches is to realize that bullets are cheap. By the time the former group has perfected their wind detection instrument, you’ll have finished your simple weapon and already hit the target.

In the world of web development, the target is your ideal offering, the bullets are your site deploys, and your customers provide the feedback mechanism. The first year of a web offering is a magical one. Your customers are most likely early adopters and love to see new features roll out every few weeks. If this results in a little bit of downtime, they’ll easily forgive you, as long as those features are sweet. In the early days of GitHub, we’d deploy up to ten times in one afternoon, always inching closer to that target.

Make good use of that first year, because once the big important customers start rolling in, you have to be a lot more careful about hitting one of them with a stray bullet. Later in the game, downtime and botched deploys are money lost and you have to rely more on building instruments to predict where you should aim.

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This is a documented gotcha with mocha. And also discussed here.

It happens when mocha gem is listed as library dependency inside rails app. The library gets loaded too soon. The fix is to load mocha after rails has booted up.

For rails < 3.0.0, this means removing -- config.gem 'mocha' -- entry from config/environment.rb and adding -- require 'mocha' -- at the bottom of test/test_helper.rb.

For rails >= 3.0.0, this means adding — :require => false — inside Gemfile entry as follows.

# Gemfile
group :test do
  gem 'mocha', :require => false
end

And then adding following line at the bottom of test/test_helper.rb:

# test_helper.rb
require 'mocha'

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sudo port install tiff -macosx imagemagick +q8 +gs +wmf
sudo gem install rmagick

Reference: http://rmagick.rubyforge.org/install-osx.html

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Sooner or later, the need arises to assign default values to model attributes. In rails this is usually done in model’s after_initialize() with a new_record? guard.

Something like:

class User
  def after_initialize
    if new_record?
      self.country = "US"
    end
  end
end

This initializes the object with proper default so the UI form gets properly populated and the database gets proper default if user hasn’t overridden it.

Sometimes, you realize that you have (pre-existing?) objects in database that also need the same default if the current value is nil. In such case, you may modify your initializer like this:

class User
  def after_initialize
    self.country ||= "US"
  end
end

This works for both scenarios: User.new and User.find.

However, it introduces a behavior that may not be apparant immediately.

$ script/console
ree> User.find(u.id)
  User Load (0.9ms)   SELECT * FROM `users` WHERE (`users`.`id` = 1) 
ree> User.exists?(:id => u.id)
  RateSearch Load (0.6ms)   SELECT `users`.id FROM `users` WHERE (`users`.`id` = 1) LIMIT 1
ActiveRecord::MissingAttributeError: missing attribute: country
/[prj]/app/models/User.rb:3:in `after_initialize'

A closer look reveals that ActiveRecord tries to be smart and only fetch ‘id’ column when performing Model.exists? call.

Many people have tripped this and logged it as a bug. The report has been silently ignored, and I believe, for good/performance reasons.

So, what do we get around it? Here’s one way.

class User
  def after_initialize
    self.country ||= "US"
  rescue ActiveRecord::MissingAttributeError
    # this should only happen on Model.exists?() call. It can be safely ignored.
  end
end

As they say, it is not a bug, it is a feature.

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http://rubular.com/

Good one!

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