Here’s my use case: I need to fetch child models but only those that have certain flags set on the parent. Here’s how you would do this using a simple boolean:

class Child
  scope :visible, include(:parent).where(visible: true)
end

However, this does not work immediately since FlagShihTzu stores any number of fields inside one column. After a little digging around in the source code I discovered that the conditions are exposed, allowing me to use them:

class Child
  scope :visible, include(:parent).where(Parent.visible_condition)
end

So easy.

The idea behind the app is simple: provide a safe environment for young children (age 2-6) to play, watch, learn and discover. It features content from television, games such as memory, a drawing tool and sing-a-long songs. The app mostly follows the website, but is adapted for touch screens.

I have young children and they keep coming back to this app again and again. We can also see this in the visitor stats. In fact the Z@ppelin team, including myself, was quite surprised when we received a call from the hosting team that we were causing a massive load on their servers. Since then I added a huge amount of caching and CDN speedups and now we’re fine.

Some numbers:

• 100.000+ downloads in 10 months time
• 60.000 children use the app every month
• 6 million pageviews per month on average

I did the back end in Ruby on Rails using JSON. The app itself was coded by Noodlewerk.

First the technical background. This website was created by me and I both wrote articles and programmed the website. Back in 2000 I did this in plain HTML, then jumped on J2EE. Looking back that was a nightmare. When Rails hit the scene in 2005 (I think) I ported everything to Rails and have been using that ever since.

In fact GO Magazine has been running every Rails version from 0.9-something until now. In recent years the website has been defunct and completely stagnant. Until now!

After a quick website design contest using freelancer.com, which was eventually won by Webdeezine from Serbia, I had SliceCraft do the HTML5 front-end. This all went very smoothly.

I coded the back-end in Rails 3.1 using the awesome asset pipeline. What does that mean? Well, it’s the Rails solution for all the CSS and javascript files that make up a modern web site. The asset pipeline makes sure all these little files are grouped together, so they can be pushed into your browser in the least amount of time possible. And when you visit www.gomagazine.nl you can see exactly that. There is only one CSS file and only one Javascript file visible to you, but actually there are lots of different files in the back end. Last but not least SliceCraft did their magic and made sure the HTML is squeeky clean. Check the source to see what I mean, it’s beautiful.

With this massive refresh, GO Magazine can continue showing all the articles written by me and my friends, when we were heavily into electronic music and DJ culture. Enjoy!

Bootstrap

Not a Ruby plugin, but Bootstrap is the quickest way to create a web site from scratch. It’s a CSS file that sets up everything just right: grid, typography, forms, navigation, modals, tooltips. It’s far better than the alternatives. github

Kaminari

First-class paging for Rails apps. A worthy successor to Will Paginate. github

Rack-rewrite

I discovered this one fairly recently. It’s Rack middleware that lets you rewrite and redirect URLs. Perfect for legacy URLs you need to support, because Rack-rewrite lets you deal with those before routes.rb, so they won’t clutter up your code. The only downside is that the rules are more or less hidden in the middleware config, so novice coders won’t easily figure out why some URLs behave like they do. github

Paperclip

Still the quintessential attachment plugin for Rails. github

Foreigner

You should care about your database. It’s the place where your, or your client’s, business lives. It’s the place where money and companies are made. Guard it with your life. Which means maintaining referential integrity between tables. Foreigner does it all, does it in the background and does it cross-platform. I love everything about it. github

As a Ruby programmer, a CI tool always struck me very C/Java-esque. There is no real build process in a scripting language, right? Well, turns out CI has other useful properties.

My gem has a (small, but thourough) spec suite. Travis runs this suite every time I make significant changes. A few minutes later I get the results in my e-mail. When everything’s OK, I know the software is good to go.

The true value dawned on me just now, where (frustratingly) Travis would report an error, but my local tests ran fine. Travis (on an older version of Ruby by default) didn’t like my use of method_missing much. And to be honest I didn’t either. So I yanked that out and replaced it with more well-behaving code. Travis passed right away! A clear example of a CI tool improving the code internals.

I am now much more confident that Zelda will play nice with all the Ruby versions out there. I will definitely add my other gems to Travis as well.

Since we now hate MySQL this had got to stop. Enter Randomizr. Include that in your Rails project and you’re golden. Just use Model.randomizr and you will receive one random record provided using ANSI SQL. Now you can migrate to PostgreSQL too! Like the big boys.

Paperclip.options[:swallow_stderr] = false

What I do know is this: ERB in Ruby 1.9 and Rails 2.3 will happily force all your templates to ASCII-8BIT while your database strings are most likely UTF-8. Hilarity ensues. There is no way to change this behaviour besides monkeypatching a bunch of internals.

So without further ado here are the monkeypatches: gist.

Drop in config/initializers and enjoy.

attachment_fu is not compatible with Passenger 3 on Ruby 1.9.2

Yes I know that’s an edge case, but it was true for me. Consider this code in attachment_fu:

require 'tempfile'

Tempfile.class_eval do
# overwrite so tempfiles use the extension of the basename.  important for rmagick and image science
  def make_tmpname(basename, n)
    ext = nil
    sprintf("%s%d-%d%s", basename.to_s.gsub(/\.\w+$/) { |s| ext = s; '' }, $$, n, ext)
  end
end

Does that make you cry? It should.

Anyway, after removing it completely my app works fine again.

Panda Maas is the children’s mascot of Maasstad Ziekenhuis in Rotterdam. He lives in this website, where you can meet the doctors, ask questions, hear jokes, download drawings and wander through the hospital.

This is the first website I’ve developed completely in Rails 3 and Rspec 2 from the start. Interestingly, over time I liked the Rspec 2 syntax so much that I now feel slightly dirty doing Rspec 1 for my other Rails websites. Also, the first deploy was pure hell; Bundler was still in prerelease and didn’t do at all what I wanted. But Bundler went release and came with deployment settings; after that it was all smooth sailing.

For those who still think you can’t develop production apps in SQLite: well, you can. Quite easily. Yes SQLite does table level locking on write; but so does MyISAM. And the read performance is just awesome. For any app that’s mostly read, using SQLite should be a no-brainer.