Ruby and Rails deprecation warnings and how to fix them

Add deprecation warnings and their solution or link to available solutions.

Global access to Rake DSL methods is deprecated. Please include Rake::DSL into classes and modules which use the Rake DSL methods.

Open your Rakefile and add the following line above YourApp::Application.load_tasks:

YourApp::Application.class_eval do
  include Rake::DSL
end

Use of ole/file_system is deprecated. Use ole/storage (the file_system api is recommended and enabled by default)...

JavaScript Garden

JavaScript Garden is a growing collection of documentation about the most quirky parts of the JavaScript programming language. It gives advice to avoid common mistakes, subtle bugs, as well as performance issues and bad practices that non-expert JavaScript programmers may encounter on their endeavours into the depths of the language.

JavaScript Garden does not aim to teach you JavaScript. Former knowledge of the language is strongly recommended in order to understand the topics covered in this guide

RSpec matcher to check if an ActiveRecord exists in the database

The attached RSpec matcher exist_in_database checks if a given record still exists in the database and has not been destroyed:

describe Ticket do
  describe '.purge_expired' do
    fresh_ticket = Ticket.create(:expiry => Date.tomorrow)
    expired_ticket = Ticket.create(:expiry => Date.yesterday)
    Ticket.purge_expired
    fresh_ticket.should exist_in_database
    expired_ticket.should_not exist_in_database
  end
end

Note that there is also [ActiveRecord::Base#destroyed?](http://apidock.com/rails/ActiveRecord/Base/destroyed...

Synchronize a Selenium-controlled browser with Capybara

When you click a link or a press a button on a Selenium-controlled browser, the call will return control to your test before the next page is loaded. This can lead to concurrency issues when a Cucumber step involves a Selenium action and a Ruby call which both change the same resources.

Take the following step which signs in a user through the browser UI and then sets a flag on the user that was just signed in:

Given /^the user "([^"]*)" signed in (\d) days ago$/ do |name, days|
  visit new_session_path
  fill_in 'Username', :w...

Monitoring Theory

Around the time in my life when I stopped ordering drinks made with more than one ingredient, I was woken up for the last time by a hypochondriac Nagios monitoring installation. If you are on-call long enough, you cultivate a violent reaction to the sound of your cell phone's text message alert. If your monitoring is overconfigured, that reaction boils over hastily, as it will interrupt you during meals, sex, sleep — all of the basics — with the excruciating operational details of your web site.

I've since developed, with the help of some n...

Keyboard shortcuts for Pivotal Tracker

Pressing the ? key will display a list of keyboard shortcuts. Available shortcuts are:

|search |/|
|help|?|
|add story|a|
|toggle backlog|<Shift> + b|
|toggle charts (graphs)|<Shift> + g|
|toggle current|<Shift> + c|
|toggle done|<Shift> + d|
|toggle history|<Shift> + h|
|toggle icebox|<Shift> + i|
|toggle my work|<Shift> + w|
|toggle labels & searches|<Shift> + l|

This is awesome.

Convert Adobe Flash FLA files into HTML5 with Wallaby

"Wallaby" is the codename for an experimental technology that converts the artwork and animation contained in Adobe® Flash® Professional (FLA) files into HTML. This allows you to reuse and extend the reach of your content to devices that do not support the Flash runtimes. 

Check that an element is hidden via CSS with Spreewald

If you have content inside a page that is hidden by CSS, the following will work with Selenium, but not when using the Rack::Test driver. The Selenium driver correctly only considers text that is actually visible to a user.

Then I should not see "foobear"

This is because the Rack::Test driver does not know if an element is visible, and only looks at the DOM.

Spreewald offers steps to check that an element is hidden by CSS:

Then "foo" should be hidden

You can also check that an el...

Add a prefix to form field IDs

If you use a form (or form fields) multiple times inside one view, Rails will generate the same id attributes for fields again.

This card presents you with a way to call something like

- form_for @user, :prefix => 'overlay' do |form|
  = form.text_field :email

and get this as HTML:

<input name="user[email]" id="overlay_user_email" (...) />

You can also put a :prefix into a field's options. Note how only the id but not the name changes as we would not want to pass an overlay_user[email] param to the controller. Sett...

Exchange messages between Javascript and Flash

Flash movies (.swf files) can talk with Javascript code embedded in the same HTML page. There are two ways to do this:

  • The preferred way is to use the ExternalInterface class to call Javascript functions from ActionScript, and to bind ActionScript functions to the Flash movie's DOM element so they can be called from Javascript.
  • The deprecated way is to use the global [fscommand](http://help.adobe....

Simple database lock for MySQL

Note: For PostgreSQL you should use advisory locks. For MySQL we still recommend the solution in this card.


If you need to synchronize multiple rails processes, you need some shared resource that can be used as a mutex. One option is to simply use your existing (MySQL) database.

The attached code provides a database-based model level mutex for MySQL. You use it by simply calling

Lock.acquire('string to synchronize on') do
  # non-th...

Continously run command under bash

Sometimes you want to run a command forever, e.g. to compile a haml to html file on the console. Use this:

$ while(true) do haml index.haml index.html; sleep 1.5; done

hyphenator

Javascript that implements client-side hyphenation of HTML-Documents.

Using Firebug Lite to inspect HTML in Internet Explorer and other browsers

You know Firebug as a Firefox extension but there is also a "Lite" version which runs purely off JavaScript.

Though all major browsers offer inspection tools you may like the Firebug style. Also, for me this is a lot better than the IE8 developer tools -- and it works in older versions of IE, too.

Get the bookmarklet over at http://getfirebug.com/firebuglite#Stable. It usually loads the JavaScript code from a remote server but you can also download it to have it run locally. If adding the bookmarklet does not work in IE, add a new book...

OscarGodson/jKey - GitHub

jQuery plugin to register callback functions to keyboard shortkuts. Keyboard events in vanilla Javascripts are super-painful to work with, so hopefully this library can help.

Dynamic conditions for belongs_to, has_many and has_one associations

Note: Consider not doing this. Use form models or vanilla methods instead.


The :conditions option for Rails associations cannot take a lambda. This makes it hard to define conditions that must be evaluated at runtime, e.g. if the condition refers to the current date or other attributes.

A hack to fix this is to use faux string interpolation in a single-quoted :conditions string:

class User < ActiveRecord::Base
  has_many :contracts
  has_one :current_contract, :class_name => 'Contract', :conditions => '...

The Difference Between jQuery’s .bind(), .live(), and .delegate()

The difference between .bind(), .live(), and .delegate() is not always apparent. Having a clear understanding of all the differences, though, will help us write more concise code and prevent bugs from popping up in our interactive applications.

Perform HTTP basic authentication in Cucumber (with or without Selenium)

This card describes a Cucumber step that lets you say:

When I perform basic authentication as "username/password" and I visit the admin area

The path component ("... the admin area") is parsed through your path_to helper in features/support/paths.rb.

Capybara

The step definition is part of Spreewald. The step has been tested with multiple versions of Capybara, Rack::Test and Selenium.

Webrat (legacy)

This is a simpler version of the step above:

When /...

In-depth HTTP traffic analysis using tcpdump & Wireshark

From time to time we're convinced that an error must be very close to the network card, OS IP stack or compiler. In reality this is quite rare, so before continuing, triple-check that the issue is not located between chair and keyboard...

If you're still convinced that a in-depth analysis of network traffic might help you, go on:

  • Find out the IP address the client causing trouble will come from.

  • Replace 147.0.0.123 with the client address, log into your web server and run:

    `remote$ sudo tcpdump host 147.0.0.123 and port 80 -s 0 -w...

Don't mix Array#join and String#html_safe

You cannot use Array#join on an array of strings where some strings are html_safe and others are not. The result will be an unsafe string and will thus be escaped when rendered in a view:

unsafe_string = '<span>foo</span>'
safe_string = '<span>bar</span>'.html_safe
[unsafe_string, safe_string].join(' ') # will incorrectly render as '&lt;span&gt;foo&lt;/span&gt;&lt;span&t;bar&lt;/span&gt;'

Bad

The solution is not to call html_safe on the joined array and if you thought it would be, you [don't understand how XSS prot...

Styling and scaling for mobile devices

If you want your application to display properly on iPad, iPhone or Android there are two things to do:

Define a stylesheet for mobile devices

Using the media attribute on stylesheet HTML tags allows you to have a CSS for mobile browsers:

<!--[if !IE]><!-->
  <%= stylesheet_link_tag 'mobile', :media => 'only screen and (max-device-width: 1024px)' %>
<!--<![endif]-->

Here I chose 1024 pixels as the maximum device width to include the iPad. If you want to target only mobile phones, pick 960 to include high-end Android d...

Computational cost of SSL connections

In January this year (2010), Gmail switched to using HTTPS for everything by default. Previously it had been introduced as an option, but now all of our users use HTTPS to secure their email between their browsers and Google, all the time. In order to do this we had to deploy no additional machines and no special hardware. On our production frontend machines, SSL/TLS accounts for less than 1% of the CPU load, less than 10KB of memory per connection and less than 2% of network overhead. Many people believe that SSL takes a lot of CPU time and...

Firefox: Remove dotted border from focused buttons

The following Sass will do the trick:

button,
input[type="reset"],
input[type="button"],
input[type="submit"],
input[type="file"] > input[type="button"]
  &::-moz-focus-inner
    border: none

There's also a plain CSS version.

Note that you can no longer visually navigate through a form with the keyboard without these borders.

Cucumber steps to test input fields for equality (with wildcard support)

Our collection of the most useful Cucumber steps, Spreewald, now supports exact matching of form fields and lets you use wildcards.

Examples:

And the "Money" field should contain "134"
# -> Only is green if that field contains the exact string "134", neither "134,50" nor "1000134"

And the "Name" field should contain "*Peter*"
# -> Accepts if the field contains "Peter" or "Anton Peter" or "Peter Schödl" etc.

And the "Comment" field should contain "Dear*bye"
# -> Accepts if the field contains "De...