So you are debugging like a boss and lost track of where you actually are in your code? No problem:

• Calling "l=" will show you the current file and line. That's a lower-case L and an equals sign.
• "where" (or "backtrace") will give you the debugger call stack, including current file and line as well. It can be quite long.

I am talking about development speed. When your application starts growing and you start adding gems, it starts to take really long to start up, be it the server, console or just running a single spec.

Zeus is smart, you don’t have to put it in your Gemfile or run it with Bundler, all you need to do is create a JSON config file via zeus init and then start the server zeus start.

After that, you’re ready to go, all you need to do is prefix every command with zeus. That means rails server becomes zeus server, `rails console...

The gem author Jonas Nicklas highlights in a Google Groups post that the release

• is not backwards compatible to 1.x versions of Capybara
• does not support Ruby 1.8.x anymore
• removes confusion with Rails' built in integration tests (you put capybara rspec integration tests into the spec/feature/... folder) and the :type metadata has been changed from :request to :feature
• throws exceptions when trying to interact with an element whose identifier is...

The very useful andand gem does not play very nice with Ruby's SimpleDelegator (or vice versa).

This following will not work:

class MyDecorator < SimpleDelegator
  def foo
  end
end

MyDecorator.new(Object.new).andand.foo

The reasons are a bit subtle, basically SimpleDelegator will "force" some methods to be delegated, so the andand method is called on the wrapped object, not the delegator.

You can fix it like this:

class Decorator < SimpleDelegator
  def an...

A technique to vastly reduce the number of join model records that need to be stored in the database.

The technique is only effective when there is a high redundancy in your data, e.g. combinations of the same 20 tags are used to label thousands of books.

The technique is also limited in that your join models cannot have additional logic, such as attributes or callbacks.

Ther has-many-with-set gem is an implementation of this technique.

If you get a stacktrace complaining about uninitialized constant MysqlCompat::MysqlRes a system library update might broke your gem.

You might have switched from MySQL to MariaDB, but forgot to rebuild your MySQL gems.

Try fully removing and re-installing the gem:

gem uninstall mysql mysql2
bundle install

When you have two models in a has_many, has_one or belongs_to association, the :inverse_of option in Rails tells ActiveRecord that they're two sides of the same association.

Example with a has_many / belongs_to association:

class Forum < ActiveRecord::Base
  has_many :posts, inverse_of: :forum
end

class Post < ActiveRecord::Base
  belongs_to :forum, inverse_of: :posts
end

Knowing the other side of the same association Rails can optimize object loading so forum and forum.posts[0].forum will reference the same o...

Capybara gives you two different methods for executing Javascript:

page.evaluate_script("$('input').focus()")
page.execute_script("$('input').focus()")

While you can use both, the first line (with evaluate_script) might freeze your browser window for 10 seconds.

The reason is that evaluate_script will always return a result. The return value will be converted back to Ruby objects, which in case of complex objects (e.g. a jQuery collection) is very expensive.

Because of this we recommend to only use evaluate_script whe...

Rarely, you might want to rebuild all gems with native extensions, because they might be compiled against outdated system libraries, resulting in some warnings or even segfaults or other ruby errors.

You can do that using

gem pristine --all

This will reset all gems to a pristine state as if you'd reinstall them, and as a side effect, rebuild all native extensions.

The above command will also help you sorting out errors like this after a distribution upgrade:

libmysqlclient_r.so.16: cannot open shared object file: No such fil...

url = 'http://www.foocorp.com/foo/bar'
URI.parse(url).host
# => www.foocorp.com

Note that this will raise an error if the given argument is not a URL.

If you need the host's full URL without path, query, fragment etc., use URI.join with a clever twist:

url = 'http://www.foocorp.com:33546/foo/bar?query=foobar#hash'
URI.join url, '/'
# => http://www.foocorp.com:33546/

In theory you can take any scope and extend it with additional joins or conditions. We call this chaining scopes.

In practice chaining becomes problematic when scope chains grow more complex. In particular having JOINs in your scope will reduce the scope's ability to be chained with additional JOINs without crashes or side effects. This is because ActiveRecord doesn't really "understand" your scope chain, it only mashes together strings that mostly happen to look like a MySQL query in the end.

**I don't generally advice against u...

In a nutshell:

If you require your Rails models manually, pay attention to the path you use. Unless you have to, don't do it at all.

Background

Consider these classes:

# app/models/user.rb

class User < ActiveRecord::Base
  validate :magic

  def magic
    errors.add_to_base('failed') if bad_things?
  end
end

^
# app/models/foo.rb

require 'user'

class Foo
  # something happens here
end

Now, when your environment is booted, Rails will automatically load your models, like User...

The (admittedly crazy) goal of this Gem is to be able to format/split all phone numbers in the world.

This is for you if you get the following strange error from the state_machine gem:

undefined method `-' for #<StateMachine::BlacklistMatcher:0x124769b0>

You probably did something like this in your state_machine ... do block:

def self.final_states
  [ :foo, :bar ]
end

transition (all - machine.final_states - [:baz]) => :target_state

Instead, define the source states like this:

def self.final_states
  [ :foo, :bar ]
end

transition (all - (mach...

The linked slidedeck holds many tips, of which I list the most interesting to me below

DATA and END

The __END__ keyword tells Ruby where a file ends – but you don't have to stop there. Any text you add after it is accessible via the DATA object.

Running the attached example file data.rb prints:

DATA is a File object to everything in the current file after "__END__"

No braces needed for 'special variables'

@instance, @@class, $global = [ 'instance', 'class', 'global' ]
puts "#@instance, #@@class, #$global"

...

The __END__ keyword tells Ruby where a file ends – but you don't have to stop there. Any text you add after it is accessible via the DATA object.

The attached example file data.rb looks like this:

puts DATA.read

__END__
DATA is a File object to everything in the current file after "__END__"

Running it with ruby data.rb prints:

DATA is a File object to everything in the current file after "__END__"

Ruby's mathn library changes Fixnum division to work with exact Rationals, so

2 / 3 => 0
2 / 3 * 3  => 0

require 'mathn'
2 / 3 => Rational(2,3)
2 / 3 * 3 => 2

While this might sometimes be quite neat, it's a nightmare if this gets required by some gem that suddenly redefines integer division across your whole project. Known culprits are the otherwise excellent distribution and [GetText](https://g...

If you get this warning on your local machine one of these steps might help:

Rebuilt the gem with the newer library

gem install --no-rdoc --no-ri nokogiri -- --with-xml2-include=/opt/local/include/libxml2 --with-xml2-lib=/opt/local/lib

If you still get the error, try to uninstall all nokogiri versions with

gem uninstall nokogiri

and install nokogiri again.

Fixing the issue on servers

However, on our servers this probably will not work. On the server, gems are stored in the ../shared/bundle/ruby/:version/gems dire...

If some of your JavaScripts fail on Internet Explorer, but only in staging or production environments, chances are that JavaScript compression is the culprit.

By default, Rails 3.2 compresses JavaScript with UglifyJS. I have seen a few cases where this actually breaks functioning JavaScript on IE (one example is the CKEditor).

I fixed this by switching to Yahoo's YUI Compressor.

To do this, do the following:

• replace the uglifier gem with the yui-compressor gem...

This describes how to migrate an existing cucumber test suite to Spreewald.

0. Add the gem

1. Include spreewald into your cucumber environment by putting
   require 'spreewald/web_steps'
   require 'spreewald/email_steps'
   # ...
   or just
   require 'spreewald/all_steps'
   into your support/env.rb.

2. Look through your step definitions for everything that might be included in Spreewald. Candidates are web_steps, shared_steps, table_steps, `em...

Cucumber_rails' old-school web-steps have been deprecated for a while, urging developers to write high-level step definitions that directly use Capybara or Webrat.

We think that's a bit drastic. More high-level steps are good, but ticking the odd check box with a general step is not always bad.

So we took the old web steps, improved them a bit, added some other favorites of ours (steps for emails, tables, [time travelling](/ma...

The ActionMailer in Rails 2 depends on a buggy version of TMail, which sometimes inserts a blank line into the mail header when sending a mail to multiple recipients. This makes the header end prematurely.

The reason why this is not exploding in your face all the time is that when you are relaying your e-mail through an MTA like Exim, it will fix this for you.

Fix for Rails if you don't have an awesome MTA

TMail is no longer maintained. The bug is fixed...