For the vast majority of rails CRUD applications, you aren’t going to need exotic SQL queries, but when you need to make assertions on the generated query, there are two options at your disposal.
Assume you have the following model:
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class Post belongs_to :author has_many :comments scope :publicly_visible, -> { where(public: true) } end |
Travis CI is an awesome continuous integration service that’s free for open-source projects.
If you’d like to test your app against multiple database engines, it’s fairly simple.
For these examples, I’m testing my app against SQLite, MySQL, and PostgreSQL.
In shutting down the AdGrok servers (talk about bittersweet…), I stopped the instances, but then remembered I wanted to shred the files first, so I clicked “start,” and was greeted by the following error:
The requested Availability Zone is no longer supported. Please retry your request by not specifying an Availability Zone or choosing us-west-1b, us-west-1c.
This last Friday I taught my “it really is rocket science” class to another hundred children (Kindergarten through 5th grade). Last year PTO Today wrote an article about Arts and Science day, and interviewed me. This year, the kids were great, I had tons of help, and the new rocket launcher designs let the kids experiment with different pressures and different launch angles. Good stuff!
Seeing this?
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rake/rdoctask is deprecated. Use rdoc/task instead (in RDoc 2.4.2+) |
Edit your Rakefile and change these lines:
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require 'rake/rdoctask' Rake::RDocTask.new(:rdoc) do |rdoc| ... |
to look like this:
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require 'rdoc/task' RDoc::Task.new do |rdoc| ... |
You may need to add gem 'rdoc' to your Gemfile, too. While you’re at it, you might want to add rdoc/ to your .gitignore, too
Seeing this?
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Installing pg (0.11.0) with native extensions /Users/mrm/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/site_ruby/1.9.1/rubygems/installer.rb:533:in `rescue in block in build_extensions': ERROR: Failed to build gem native extension. (Gem::Installer::ExtensionBuildError) /Users/mrm/.rvm/rubies/ruby-1.9.2-p180/bin/ruby extconf.rb checking for pg_config... no No pg_config... trying anyway. If building fails, please try again with --with-pg-config=/path/to/pg_config checking for libpq-fe.h... no Can't find the 'libpq-fe.h header *** extconf.rb failed *** |
Wondering how or where to get this mythical pg_config? It’s part of the PostgreSQL package. If you’re running MacPorts, it’s easy:
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sudo port install postgresql90 |
Then, following the instructions on the RVM website, run
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gem install pg -- --with-pg-config=/opt/local/lib/postgresql90/bin/pg_config |
Launching git gui from the command line, when built with MacPorts, causes an irritating dialog to pop up:
The solution is simple:
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$ sudo port install aspell aspell-dict-en |
Update January 2012: since originally writing this post, I’ve recanted my love for rails plugins — having a stubbed rails app in your plugin’s test directory is just too funky. If you need an example of a rails 3.2.x plugin that uses rspec 2 and has Travis CI integrated, check out closure_tree. But even that setup feels to heavyweight.
The original post follows.
There are a lot of posts on how to build rubygems. With Rails 3.1, though, they’re all old and busted.
The new hotness is built right into rails now. Just incant
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rails plugin new APP_PATH |
You’ll get:
When you run rake, you’ll see “rake/rdoctask is deprecated. Use rdoc/task instead (in RDoc 2.4.2+)”. To remedy, follow these steps.
The Edge edition of the Ruby on Rails Guides has more information.
In rebuilding PhotoStructure on Rails, I was surprised that one of the most popular gem for trees used a nested set model. Nested sets are performant for reads, but for adding and deleting nodes, it’s extremely expensive — on average, half of the rows for your model acting as a nested set have to be updated for every add or delete. That’s crazy-talk! It requires a table-level lock for something that, at least for PhotoStructure, is a very common task. To top it off, the gem doesn’t even do the lock!
I then found the ancestory gem, which works by materializing the ancestral path as a string and storing that as a column. Bill Karwin’s excellent Models for hierarchical data presentation describes this as the Path Enumeration algorithm, which doesn’t have referential integrity, and relies on performant LIKE selects.
As the tag hierarchies in PhotoStructure are never moved, closure trees should prove to be ideal. It’s an excellent excuse to learn how to build and publish a rails plugin gem, so I’ve built a new gem to support closure trees: github.com/mceachen/closure_tree.
1.0.0.beta1 released. All public methods have test coverage.
1.0.0.beta2 and 1.0.0.beta3 were released, which added find_or_create class and instance methods, ancestry_path, and root instance methods. Documentation is on the README and in the rdocs.
1.0.0.beta5 is released, which cleaned up the ancestor and descendant relationships to use has_and_belongs_to_many, and adds leaves class and instance methods.
2.0.0.beta1 is released, which added the :dependant option, switched from an embedded dummy rails app for testing to rspec, and much better test coverage (including tests and fixes for a couple reported issues) under sqlite, MySQL, and PostgreSQL.
3.0.0 is released, which supports polymorphic trees.
In AdGrok’s GrokBar, we inject a “heads-up display” on pages that the user is advertising. The heads-up display is actually an iframe that’s positioned within a browser-extension-injected div, and that iframe renders content from our secure server farm. You can see a demo video here (and see that we truly spared no expense on the voice-over talent!).
I wanted to make our extension’s button-click incant a javascript method that was inside the GrokBar’s iframe. I found this horrible hack, but every time a javascript timer scrapes a hidden DOM element, or mucks with the URL fragment of an iframe src in order to send messages, the code gods kick a puppy.
