Paperclip file rename

While developing an application with Sebastián that allow users to upload videos with some file name restrictions, meaning that it must contain only A-Z and 0-9 digits, underscores (_) as a valid component as well, and also the name must be preceded by it’s own #id, we came up with the need of applying this custom filter to each uploaded video. After doing some research on paperclip source code and internet tutorials, we suggest the following solution:

class Video < ActiveRecord::Base
  has_attached_file :video,
    :path => ":rails_root/public/system/:attachment/:id/:style/:normalized_video_file_name",
    :url => "/system/:attachment/:id/:style/:normalized_video_file_name" 

  Paperclip.interpolates :normalized_video_file_name do |attachment, style|
    attachment.instance.normalized_video_file_name
  end

  def normalized_video_file_name
    "#{self.id}-#{self.video_file_name.gsub( /[^a-zA-Z0-9_\.]/, '_')}" 
  end
end

path default => ":rails_root/public/system/:attachment/:id/:style/:filename" 
url default => "/system/:attachment/:id/:style/:filename"

Values preceded by ’:’ are the standard interpolations paperclip has. For further information on this visit http://wiki.github.com/thoughtbot/paperclip/interpolations.

What we did was change * with *:normalized_video_file_name in both path and url, being the second a custom interpolation and then added the ‘normalized_video_file_name’ method to video.rb.

By doing this we not only achieve a way for paperclip to handle the file by this normalized way, but also have a method to access the normalized file name, plus being able to access the original file name through paperclip video_file_name method.

So remember on video_file_name you have the uploaded filename and on normalized_video_file_name you have the server filename.

TwitterAuth Integration Testing

Michael Bleigh’s TwitterAuth gem is truly full of awesome. It’s a complete OAuth authentication and API access solution for building Twitter apps with Rails. It uses familiar conventions borrowed from the Restful Authentication plugin, too. If you’re building a Rails-based app and you want to allow your users to Sign in with Twitter there’s just no better way to go.

For this particular app, I’m using the dynamic duo of Cucumber and Webrat to whip up integration tests. Since I initially stumbled a little bit when thinking about how to test integrated authentication against an external source like Twitter, I thought I’d doc the solution here in case other people were having the same issue.

Ready? Let’s do it.

Setup

First, install the TwitterAuth gem and use the provided generator to whip up the appropriate facilities. You’ll need to register your Twitter application accounts too. Or you know what? Screw it. If you want to make this super easy on yourself, Mike wrote a really great Twitter app Rails template that does all the setup for you, including walking you through getting the dev accounts. It’s nice, try it out. You’ll be up and writing Twitter apps in no time.

For the rest of this I’m going to assume that you have all of that working, and have installed Cucumber too. Don’t have Cucumber? Install it using RubyGems and then just run script/generate cucumber inside your Rails app.

Authentication Feature

So let’s write a Cucumber feature to test authentication in our boilerplate Twitter template application. Put the following in features/authentication.feature:

Feature: Authentication
In order to create and edit games
As a user
I want to sign in with Twitter

  Scenario: Login via Twitter
    When I go to "the homepage"
    And I follow "Login via Twitter"
    And Twitter authorizes me
    Then I should see "Logged in as"

  Scenario: Checking login status
    Given I am signed in
    When I go to "the homepage"
    Then I should see "Logged in as"

  Scenario: Log out
    Given I am signed in
    When I go to "the homepage"
    And I follow "Log out"
    Then I should see "Login via Twitter"

Step Definitions

Next, you’ll need to write step definitions to satisfy the missing steps. Do that by creating a file called features/step_definitions/auth_steps.rb. The content of the file should define the following two steps:

Given /^I am signed in$/ do  
  visit login_path
  visit oauth_callback_path
end  

When /^Twitter authorizes me$/ do
  visit oauth_callback_path
end

Fake Style

The secret sauce here is FakeWeb. We’ll use it to fake out responses from the Twitter auth service so that your integration tests stay local (and reliable). Make sure to gem install fakeweb, and add the following to tests/environments/cucumber.rb:

config.gem "fakeweb", :version => ">= 1.2.5"

Now edit Cucumber’s features/support/env.rb file:

FakeWeb.allow_net_connect = false
FakeWeb.register_uri(:post, 'http://twitter.com/oauth/request_token', :body => 'oauth_token=fake&oauth_token_secret=fake')
FakeWeb.register_uri(:post, 'http://twitter.com/oauth/access_token', :body => 'oauth_token=fake&oauth_token_secret=fake')
FakeWeb.register_uri(:get, 'http://twitter.com/account/verify_credentials.json', :response => File.join(RAILS_ROOT, 'features', 'fixtures', 'verify_credentials.json'))

Here we’re stubbing out the interaction with Twitter auth, and responding to all outbound authorization attempts with canned data. Note that this references a fixture file, containing a sample verify_credentials API response from Twitter. You can obtain a copy using curl from the comfort of your terminal prompt (substitute your own username and password):

curl -i -u user:pass "http://twitter.com/account/verify_credentials.json" > verify_credentials.json

And We’re Done

Alright that should do it. Go ahead and run rake features. Everything should be green. And green is good. If you need to write other features that are dependent on a login requirement, you can reuse the same “Given I am signed in” step that we created earlier.

Thanks to b.kocik, whose original post on using FakeWeb to stub Twitter auth was 80% of the solution I needed here.

Windy City Rails Deadline Approaching Fast

Many of us in the Midwest are looking forward to the Windy City Rails Conference on September 12, 2009.

The deadline is very rapidly approaching for the early bird rates ($99 conference only, or $199 for the conference plus a complete 3-hour tutorial session).

I’m doing the morning tutorial called REST 101: Best Practices for Rails Developers for those of you who are relatively new to Rails or trying to get a handle on what the whole REST thing is all about.

So register now for the conference and/or tutorial. Profits from the tutorials/conference go to charity. So we’ll learn a lot, have fun, and support a good cause all in one day.

Questions? Leave a comment below and I’ll try to respond quickly.

Thanks! See you there!