Idiosynchracy With Apache Rewrites
Posted on September 22, 2009, under GNU/Linux.
Did you know that it’s not possible to apply an Apache rewrite condition to multiple rewrite rules? I thought this would work, but requests from every IP address were being redirected:
RewriteCond %{REMOTE_ADDR} ^10\.0\.10\.10$
RewriteRule ^uploads/(.*)$ /wp-content/uploads/$1
RewriteRule (.*) http://deadorange.com/blog$1 [L,R=301]
It turns out that RewriteCond directives only apply to the following RewriteRule. So my rewrite directives above were equivalent to “If the request came from 10.0.10.10, rewrite /uploads/.* to /wp-content/uploads/.* .Next, redirect everyone to http://deadorange.com/blog$1 .”
Unfortunately, the only solution is to repeat the condition:
RewriteCond %{REMOTE_ADDR} ^10\.0\.10\.10$
RewriteRule ^uploads/(.*)$ /wp-content/uploads/$1
RewriteCond %{REMOTE_ADDR} ^10\.0\.10\.10$
RewriteRule (.*) http://deadorange.com/blog$1 [L,R=301]
That isn’t very DRY, but if it’s the only way, we have to live with it!
Importing large WordPress blogs
Posted on September 17, 2009, under GNU/Linux.
I just finished importing a WordPress blog with >1500 posts into a different WordPress blog. Importing the posts succeeded, but the last few steps at the end failed, like recalculating how many posts are in each category. This happened because the page always timed out; the import took more than 10 minutes.
If you find yourself with this problem, the fix is easy:
- First, comment out the following line in wp-admin/import/wordpress.php . In WordPress 2.8.4, it’s line 367.
set_time_limit( 60 );
- Configure your web server to allow PHP scripts to execute for a long time. In Apache, you do that with the “Timeout” directive:
Timeout 6000
This can be put within a specific virtual host, or configured globally.
- Increase PHP’s max execution time. This is done with the “max_execution_time” setting in the appropriate php.ini :
max_execution_time = 600 ; Maximum execution time of each script, in seconds
or within your web server’s configuration, if that’s allowed. For example, within Apache, you include this globally, or within a virtual host:
<IfModule mod_php5.c> php_value max_execution_time 6000</IfModule>
Hashes and Frozen Keys
Posted on August 21, 2009, under Coding.
The hash class freezes keys that are strings:
This can be a problem if you want to use those keys later on…more specifically, if you want to extract and edit those strings:
Unfortunately, those strings will have to be duped or cloned:
Sinatra and Passenger/mod_rails
Posted on August 13, 2009, under Coding.
If you want Apache to serve up a Sinatra app, your best bet is to use Passenger (AKA mod_rails).
All your app needs is the usual Rackup config file (config.ru) in the app’s root directory, and the directory public/ .
There’s one caveat, though: if you have a file named environment.rb , do not put it in config/ .
If mod_rails finds config/environment.rb , it’ll think your app runs on Rails:
Ruby in Etch
As some of you may know, Ruby and Debian’s ways of packaging software go together like Darwin and religious zealots…as in, they don’t. So how should you install Ruby when using Debian Stable? How do you stay up-to-date with new versions of Ruby and gems?
By using Backports, and not worrying so much.
First, setup your box to be able to install backports of packages. Next, uninstall any Ruby-related packages. Yeah, that’s right. Do you know why? Because, if you’re running Etch, you’re using Ruby 1.8.5! Egad! That’s almost medieval. Make sure to uninstall irb and rdoc, too.
Now it’s time to install shinier versions…1.8.7, to be exact:
$ sudo aptitude install -t etch-backports libruby1.8 ruby1.8 rdoc1.8 irb1.8
All of that should be on one line.
There you have it. Now you’ve got Ruby 1.8.7 on Debian Stable (AKA “Etch”). Ruby’s not complete without RubyGems, though. Download the latest version to /usr/src/ , and extract it:
$ cd /usr/src/$ wget http://rubyforge.org/frs/download.php/45905/rubygems-1.3.1.tgz$ tar zxf rubygems-1.3.1.tgz
Then run the setup utility:
$ cd rubygems-1.3.1/$ sudo ruby setup.rb
Let’s do one last thing to make life easier. The RubyGems setup script installed the “gem” command as /usr/bin/gem1.8 . I don’t want to have to type that “1.8″ every time.
$ cd /usr/local/bin/$ sudo ln -v -s /usr/bin/gem1.8 gem
There. Now we can run “gem” like the rest of the world.
Easy? Yar.
Default stegosaurses
Ever heard of Jonathan Viney’s active_record_defaults plugin? It’s fantastic. In a nutshell, it enables you to specify default values for model attributes. If an attribute isn’t set when initialising a new instance, the attribute’s set to whatever the default value is.
For example, let’s rebuild that Stegosaurus class from a previous post:
class Stegosaurus < ActiveRecord::Base attr_accessible :tail_spikes, :back_plates validates_numericality_of :tail_spikes,nly_integer => true, :greater_than_or_equal_to => 0 validates_numericality_of :back_plates,
With that, if we created a new Stegosaurus and didn’t specify any attributes, not only would it have no tail spikes or back plates, but the model instance wouldn’t be valid.
To fix that, all we need to do is add two lines:
class Stegosaurus < ActiveRecord::Base attr_accessible :tail_spikes, :back_plates default :tail_spikes => 4 default :back_plates => 6 validates_numericality_of :tail_spikes,
And voila, new Stegosaurus objects will automatically have 4 tail spikes and 6 back plates:
>> s = Stegosaurus.new=> #<Stegosaurus tail_spikes: 4, back_plates: 6>>> ?> s.tail_spikes=> 4>> s.back_plates=> 6
However, if used improperly, this can lead to several hours of pounding your head on your desk. Note that that the default values we used above, 4 and 6, are immutable objects. You can’t change them. You can perform operations on them, such as addition (4 + 1), but that never changes the object.
Say we want our Stegosaurus class to have an array specifying its diet that defaults to “fern” and “cycad”:
class Stegosaurus < ActiveRecord::Base attr_accessible :tail_spikes, :back_plates, :diet default :tail_spikes => 4 default :back_plates => 6 default :diet => %w(fern cycad) validates_numericality_of :tail_spikes,
That looks right. But watch this:
=> charles = Stegosaurus.new=> #<Stegosaurus tail_spikes: 4, back_plates: 6, diet: ["fern", "cycad"]>>> ?> arnold = Stegosaurus.new=> #<Stegosaurus tail_spikes: 4, back_plates: 6, diet: ["fern", "cycad"]>>> ?> charles.diet < < 'moss'=> ["fern", "cycad", "moss"]>> ?> arnold.diet=> ["fern", "cycad", "moss"]
We didn’t mean to do that…Arnold doesn’t want to eat moss!
At the moment, when the Stegosaurus class is initialised, it creates one Array for the default “diet” attribute of all future Stegosaurus objects. In other words, Charles’ and Arnolds’ “diet” attributes were references to the same object:
>> charles.diet.object_id=> 19103090>> ?> arnold.diet.object_id=> 19103090
How do we fix that? We tell the Stegosaurus class to create a new Array for each model instance. Simply change this:
default :diet => %w(fern cycad)
to this:
default :diet => Proc.new { %w(fern cycad) }
Now each time we create a new Stegosaurus, that Proc will fire, and create a new “diet” Array:
=> charles = Stegosaurus.new=> #<Stegosaurus tail_spikes: 4, back_plates: 6, diet: ["fern", "cycad"]>>> ?> arnold = Stegosaurus.new=> #<Stegosaurus tail_spikes: 4, back_plates: 6, diet: ["fern", "cycad"]>>> ?> charles.diet < < 'moss'=> ["fern", "cycad", "moss"]>> ?> arnold.diet=> ["fern", "cycad"]
I highly recommend giving active_record_defaults a try. It’s very handy, and very easy to use.
And by the way, yes, I was bitten by this problem. Why else would I be writing about it! Can you guess how I discovered it, though? … My tests picked it up!
Toblerone
Posted on January 23, 2009, under Other.
Why is Toblerone so damn tasty? Y’know what? It doesn’t matter. All that matters is access to it when desired. My parents each gave me a huge Toblerone bar for Christmas. The first one went quickly, and I’ve been savouring the second one…but it’s nearly done, too!
Windows Preview: BSOD
Posted on January 16, 2009, under Other.
The power went out last night, so I’m at my Dad’s house right now, leeching his heat, electricity, and intertubes connection.
I opened up Finder, and noticed that MacOS had found a computer on the LAN. I clicked “Get Info” on it, and well..I’ll let the image speak for itself:
I love finding small touches like that. It reminds me that there are real people at work behind the things we use every day.
Friends don’t let friends code without tests
But what if your friends don’t write tests? Or what if you’re just lazy? Well, if the latter applies, that’s your own damn fault. But if nobody around you tests their code, you’re probably not going to be motivated to test your own code. But, fear not! RSpec is here!
RSpec is a really awesome testing framework. By “awesome”, I mean that it:
- makes it easy to write tests;
- makes your tests easy to read;
- gives you an easy development path to follow.
It accomplishes this by following behaviour-driven development (BDD). If you’re not a keener, don’t bother following that link. Just read on for the stegosaurus.
With BDD, you write specs that describe your application’s behaviour in terms of what it should and shouldn’t do.
Let’s write an app to mimic one of my favourite dinosaurs. And while we’re at it, we’ll do some testing. But first, install RSpec:
sudo gem install rspec
Stegosauruses are known for 2 things. Let’s start with those awesome tail spikes:
class Stegosaurus attr_accessor :tail_spikesend
That’s pretty simple. So how do we spec this? We start off by describing what we want our application to do. In this case, we should be able to grab the “tail_spikes” attribute:
require 'stegosaurus' describe Stegosaurus doit 'should have tail spikes' do steggie = Stegosaurus.new steggie.should respond_to :tail_spikes steggie.should respond_to :tail_spikes=endend
Run the spec, and we’re off to the races!
$ spec stegosaurus_spec.rb. Finished in 0.015328 seconds 1 example, 0 failures
We should also spec setting the number of tail spikes, so let’s update the spec:
require 'stegosaurus' describe Stegosaurus doit 'should have tail spikes' do steggie = Stegosaurus.new steggie.should respond_to :tail_spikes steggie.should respond_to :tail_spikes= steggie.tail_spikes = 4 steggie.tail_spikes.should equal 4endend
That’s one of the most readable and easy-to-understand tests you’ve ever seen, eh?
Stegosauruses are also known for the huge plates on their backs:
class Stegosaurusattr_accessor :tail_spikesattr_accessor :platesend
The spec should be pretty obvious:
require 'stegosaurus' describe Stegosaurus doit 'should have tail spikes' do steggie = Stegosaurus.new steggie.should respond_to :tail_spikes steggie.should respond_to :tail_spikes= steggie.tail_spikes = 4 steggie.tail_spikes.should equal 4end it 'should have plates' do steggie = Stegosaurus.new steggie.should respond_to :plates steggie.should respond_to :plates= steggie.plates = 12 steggie.plates.should equal 12endend
Notice, though, that we’re beginning to repeat ourselves. In both of those examples (#it blocks), we create a new Stegosaurus. Let’s tidy that up a bit:
require 'stegosaurus' describe Stegosaurus dobefore :each do @steggie = Stegosaurus.newend it 'should have tail spikes' do @steggie.should respond_to :tail_spikes @steggie.should respond_to :tail_spikes= @steggie.tail_spikes = 4 @steggie.tail_spikes.should equal 4end it 'should have plates' do @steggie.should respond_to :plates @steggie.should respond_to :plates= @steggie.plates = 12 @steggie.plates.should equal 12endend
What we did there is tell RSpec to create a new Stegosaurus before each example is run. To make the stegosaurus available to the examples, it simply needs to be an instance variable.
When running your specs, there are a few different ways to format the output. I tend to use the default and “specdoc” formats. Currently, our spec’s output looks like this:
$ spec stegosaurus_spec.rb.. Finished in 0.01591 seconds 2 examples, 0 failures
But we can also tell RSpec to spit out a summary of our specs:
$ spec stegosaurus_spec.rb --format specdoc Stegosaurus- should have tail spikes- should have plates Finished in 0.057443 seconds 2 examples, 0 failures
Our Stegosaurus class is feeling a bit weird, though..technically, we can set the “tail_spikes” and “plates” attributes to any object:
$ irb>> require 'stegosaurus'=> true>>?> steggie = Stegosaurus.new=> #<Stegosaurus:0x602afc>>>?> steggie.tail_spikes = "we don't want to be able to do this!"=> "we don't want to be able to do this!"
So we need to restrict those two attributes to integers:
class Stegosaurusattr_reader :tail_spikesattr_reader :plates def tail_spikes=(number_of_tail_spikes) raise ArgumentError, 'The first argument (number_of_tail_spikes) must be a Fixnum.' unless number_of_tail_spikes.is_a? Fixnum @tail_spikes = number_of_tail_spikesend def plates=(number_of_plates) raise ArgumentError, 'The first argument (number_of_plates) must be a Fixnum.' unless number_of_plates.is_a? Fixnum @plates = number_of_platesendend
With that done, what do we need to change in our specs? We need to spec the behaviour of the 2 new setter methods:
require 'stegosaurus' describe Stegosaurus dobefore :each do @steggie = Stegosaurus.newend describe '"tail_spikes" attribute' do it 'can only be set to an integer' do Proc.new { @steggie.tail_spikes = 'asdf' }.should raise_error ArgumentError, 'The first argument (number_of_tail_spikes) must be a Fixnum.' @steggie.tail_spikes = 4 @steggie.tail_spikes.should equal 4 endend describe '"plates" attribute' do it 'can only be set to an integer' do Proc.new { @steggie.plates = 'asdf' }.should raise_error ArgumentError, 'The first argument (number_of_plates) must be a Fixnum.' @steggie.plates = 12 @steggie.plates.should equal 12 endendend
Most of that is pretty self-explanatory. However, notice that we’ve just nested #describe inside of the original #describe…twice! We do this because it makes are specs read more fluidly, and it groups examples (#it blocks) together. And inside these inner-#describes, we can do anything we talked about earlier, like setup a before-block.
Let’s add one more attribute…a name:
class Stegosaurusattr_reader :tail_spikes, :plates, :name def tail_spikes=(number_of_tail_spikes) raise ArgumentError, 'The first argument (number_of_tail_spikes) must be a Fixnum.' unless number_of_tail_spikes.is_a? Fixnum @tail_spikes = number_of_tail_spikesend def plates=(number_of_plates) raise ArgumentError, 'The first argument (number_of_plates) must be a Fixnum.' unless number_of_plates.is_a? Fixnum @plates = number_of_platesend def name=(name) raise ArgumentError, 'The first argument (name) must be a String.' unless name.is_a? String @name = nameendend
And now the specs look like:
require 'stegosaurus' describe Stegosaurus dobefore :each do @steggie = Stegosaurus.newend describe '"tail_spikes" attribute' do it 'can only be set to an integer' do Proc.new { @steggie.tail_spikes = 'asdf' }.should raise_error ArgumentError, 'The first argument (number_of_tail_spikes) must be a Fixnum.' @steggie.tail_spikes = 4 @steggie.tail_spikes.should equal 4 endend describe '"plates" attribute' do it 'can only be set to an integer' do Proc.new { @steggie.plates = 'asdf' }.should raise_error ArgumentError, 'The first argument (number_of_plates) must be a Fixnum.' @steggie.plates = 12 @steggie.plates.should equal 12 endend describe '"name" attribute' do it 'can only be set to a string' do Proc.new { @steggie.name = ['not valid'] }.should raise_error ArgumentError, 'The first argument (name) must be a String.' @steggie.name = 'Rupert' @steggie.name.should equal 'Rupert' endendend
Let’s run that spec now:
$ spec stegosaurus_spec.rb..F 1)'Stegosaurus "name" attribute can only be set to a string' FAILEDexpected "Rupert", got "Rupert" (using .equal?)./stegosaurus_spec.rb:37: Finished in 0.02225 seconds 3 examples, 1 failure
Hrmmm, that’s no good. But that’s a fairly useful error message, eh?…well, sort of. It’s telling us what it expected, and what it received. The thing is, it expected “Rupert” and got “Rupert”, so what’s going on? The problem lies in the fact that you can’t use #equal? to compare strings, and that’s exactly what we’re doing. If you don’t believe me, try it for yourself:
$ irb>> 'Rupert'.equal? 'Rupert'=> false
BTW, did you notice the “(using .equal?)” hint that RSpec gave us?
Enough banter. All we need to do is change this:
@steggie.name.should equal 'Rupert'
to this:
@steggie.name.should == 'Rupert'
Shall we view our specs in all their glory now?
$ spec stegosaurus_spec.rb --format specdoc Stegosaurus "tail_spikes" attribute- can only be set to an integer Stegosaurus "plates" attribute- can only be set to an integer Stegosaurus "name" attribute- can only be set to a string Finished in 0.018755 seconds 3 examples, 0 failures
Those’re the absolute basics of RSpec. If you’re thirsty for more, check out the RSpec website.
Testing…it’s what life’s all about
Posted on January 7, 2009, under Coding.
I just read a great call to action by John Nunemaker. He wants to see everyone writing tests for their code, and has decided to “post like a superhuman fiend until everyone is testing”. He’s on to something!
With that said, I’m joining in. I primarily use RSpec, so I’ll be focussing on that, but we’ll give Cucumber and other tools a go, and we’ll be starting with the basics.
So subscribe to our feeds, and stay tuned!