Background

wshlst uses a lot of Javascript. When developing, I want to have all of my JS files listed in my index.html page. But in production mode, I want a single JS file. So I wrote a script to read in my index.html file, find all the references to my Javascript files, and write out a new HTML file that contains a reference to a single JS file that was created by concatenating and compressing all the JS files.

As an example, have a look at what my index.html page looks like in development mode and in production mode.

Ruby Script → Rake

When a server move prompted me to upgrade to Subversion and Capistrano, I decided to turn my Ruby script into a Rake task that I could trigger from my Capistrano deploy: minify.rake

Capistrano

I added a line to my Capistrano deploy.rb file to run rake minify on the server after updating from Subversion:

run "cd #{release_path} && rake minify RAILS_ENV=#{rails_env}"

Apache

I also added a few lines to my httpd.conf file to support this. First, since the Rake task combines all the JS files into a single JS file but Capistrano deploys the entire app, I wanted to restrict access to everything in the javascripts directory:

# Don't allow access to the javascripts directory (all JS should be in minified js file)
RewriteRule ^/javascripts/ - [F]

Then, because the Rake task reads index.html and outputs a file called index-mini.html, I wanted to send all requests for / and /index.html to /index-mini.html:

# Rewrite index.html to index-mini.html
RewriteRule ^/index.html$ /index-mini.html [QSA]

# Rewrite index to check for static
RewriteRule ^/$ /index-mini.html [QSA]

Why Not Use AssetPackager?

For a normal Rails application, AssetPackager is probably the right solution to this problem. However, wshlst doesn’t use Rails to generate the UI (it’s all done in Javascript), so AssetPackager wouldn’t work.

I contemplated having a per-user time zone setting, but that seemed complicated. So I decided to just show how old the item is. For that, I needed to write two things. I’m posting them here in case anyone else finds them useful.

RelativeDate.js

First, I needed a simple relative date formatter, so I wrote a simple one. Given two dates, it returns a string like

4 days ago

or

26 hours ago

Here’s the code and the JsUnit test:

RelativeDate.js
RelativeDateTest.html

ServerTime.js

The timestamps of the items I’m displaying are stored in the database, so they are based on the clock of my database server. The relative dates are calculated in Javascript, so they are based on the clock of the user, which might be hours or just minutes off from the database server time.

The first thing my app does when it loads is checks to see if the user is logged in, so I decided to piggyback the current server time along with the response. Since the client and server talk using JSON, it’s simple to add another property to the response:

def current
  ...
  render_json({
    :success => true,
    :user => user,
    :servertime => dbtime()
  }.to_json)
end

...

def dbtime
  ActiveRecord::Base
    .connection
    .select_all("select unix_timestamp(now()) as now")[0]["now"]
    .to_i
end

I wrote a ServerTime class on the client side and I initialize it when the app receives the current user response from the server:

this.serverTime = new ServerTime(json.servertime);

Here’s the code (it’s very simple):

ServerTime.js

Putting It Together…

And now to display the relative time, my app only has to do this:

var updated = new Date(item.updated_at * 1000);
element.insert(new RelativeDate(updated, app.serverTime.get()).toString());

Easier said than done

Here’s the error I got:

It was looking for header files in /usr/lib/ruby/1.8/powerpc-darwin8.0, but they weren’t there; they were in /usr/lib/ruby/1.8/universal-darwin8.0.

The Solution

The solution was simple enough: create symlinks to the header files:

$sudo ln -s ../universal-darwin8.0/*.h ./
$sudo gem install termios

Creating the join table

Starting with tables foos and bars, I created a join table bars_foos. (Rails expects the join table’s name to be a concatenation of the two table names in alphabetical order).

Reading attributes

I added an attribute baz to bars_foos. I had originally tried to access it with:

myFoo.baz

but that didn’t work. It turns out that I needed to force Rails to do the join before accessing the attribute, which makes sense when you think about it (but it took me a while before my little brain thought about it correctly):

myFoo.bars.baz

Adding attributes

Use the well-documented push_with_attributes method:

myFoo.bars.push_with_attributes(bar, :baz => "fez")

Updating attributes

Apparently you can’t. Luckily, in my app the attribute is immutable. Other people have suggested deleting and re-inserting the row which I imagine shouldn’t be a problem for most applications.

One big problem is that it can’t run all your tests. So we wrote a test suite class that runs all tests and can be run from Test::Unit:

require 'test/unit'

Dir.chdir("test")
@@test_files = Dir.glob("**/*_test.rb")
@@test_files.each {|x| require x} 

class TestSuite
  def self.suite
    suite = Test::Unit::TestSuite.new

    @@test_files.each do |filename|
      File.open(filename) do |file|
        file.each_line do |line|
          if match = (/class\s+(\w+Test)/).match(line)
           suite << eval(match[1] + ".suite")
          end
        end
      end
    end

    return suite

  end
end

Here’s what ended up working for me. It’s based on the instructions on Jamie’s Blogomatic.

1. Install the XCode tools from the Tiger DVD.

2. Download and run the Ruby on Rails installer from: http://users.tpg.com.au/aarnold/Ruby%20on%20Rails.zip.

3. Download and run the MySQL installer (I used version 4.1.11): http://dev.mysql.com/downloads/index.html.

4. Start mysql: bash$ sudo /usr/local/mysql/bin/mysqld_safe

5. Put mysql into the background: ctrl-z and then bash$ bg

6. Update gems: bash$ sudo gem update

7. Install the mysql gem from the remote source: bash$ sudo gem install -r mysql -- --with-mysql-dir=/usr/local/mysql

8. Compile and install the MySQL API module from here: http://www.tmtm.org/en/mysql/ruby/.

9. All done!