Accessing pseudo elements via JavaScript or jQuery is often painful/impossible. However, accessing their styles is fairly simple.

Using getComputedStyle

First, find the element in question.

let element = document.querySelector('.my-element') // or $('.my-element').get(0) when using jQuery

Next, use JavaScript's getComputedStyle. It takes an optional 2nd argument to filter for pseudo elements.

let style = window.getComputedStyle(element, '::before')
let color = style.getPropertyValue('background-color...

Percent Notation

We already know that that we can create strings using the percent notation:

%(<foo="bar's ton">) is perfectly fine Ruby.

Modifier

But there is more. The curly brackets ({}) are interchangable with most unicode characters (e.g. square brackets[]).
Furthermore, you can add a "modifier" to the percent notation to control the return type of th...

Grazie Lite

Rubymine 2024.3 bundles Grazie Lite by default. You need to enabled "German" under Settings/Preferences | Editor | Natural Languages.

Hunspell (legacy)

1. Install the Hunspell plugin and restart Ruby Mine
2. Run sudo apt install hunspell-de-de
3. Select /usr/share/hunspell/de_DE.dic in File > Settings > Editor > Spelling > Custom Directory +

![Screenshot_from_2018-10-17_16-47-03.png](https://makandracards.com/makandra/57341-rubymine...

Starting with Ruby 2.0 you can define methods with keyword arguments.

In 2.1+ required keyword arguments can be defined by using a colon without default value:

def match(value, ignore:)
  # ...
end

To accomplish something similar in ruby 1.8, use:

def match(value, options = {})
  ignore = options.fetch(:ignore)
  # ...
end

When debugging your application, you will come across objects created by some gem or framework. You don't have the source code at hand, still need to inspect this object. Here are some tools to do so:

Relevant methods

@object.methods - Object.instance_methods returns a list of methods excluding methods inherited from Object. This makes the methods list drastically more relevant. You can also try subtracting other base classes like ActiveRecord::Base.methods etc.
To further narrow it down you can also just look at public methods...

Normally you can list all gems of the current ruby version with gem list, which also includes the gems of you Gemfile. These can be uninstalled with gem uninstall gemname.

List and uninstall a gem installed via Bundler from Github

This does not work for gems installed directly from Github. They do not appear in gem list.

Show all gems installed via Github by bundler:

ls ~/.rbenv/versions/2.4.1/lib/ruby/gems/2.4.0/bundler/

Remove a gem installed via Github by Bundler:

rm -rf ~/.rbenv/versions/2.4.1/lib/ruby/gems/2....

Phusion Passenger changed the way how it gets restarted several times. Through the project's history, these all were valid:

• touch tmp/restart.txt
• sudo passenger-config restart-app /path/to/app
• passenger-config restart-app /path/to/app

You should not need to know which one to use. Instead, the capistrano-passenger gem will choose the appropriate restart mechanism automatically based on your installed the passenger version.

Installation

1. Add to your Gemfile:

   gem 'capistr...
   

In this example we assume that not only the storage gem changes but also the file structure on disc.

A general approach

Part A: Create a commit which includes a script that allows you to copy the existing file to the new file structure.

Part B: Create a commit which removes all paperclip logic and replace it with the same code you used in the first commit

Part A

Here are some implementation details you might want to reuse:

• Use the existing models to read the files from
• Use your own carrierwave models to write t...

A JavaScript error in an E2E test with Selenium will not cause your test to fail. This may cause you to miss errors in your frontend code.

Using the BrowserConsole helper below you can check your browser's error console from your E2E tests.

The following will raise BrowserConsole::ErrorsPresent if there is an error on the browser console:

BrowserConsole.assert_no_errors!

Ignoring errors

You can ignore errors by their exact message:

BrowserConsole.ignore('Browser is burning')

You can ignore errors with me...

If you use transactional_fixtures or the database_cleaner gem with strategy :transaction, after_commit callbacks will not be fired in your tests.

Rails 5+

Rails 5 has a fix for this issue and no further action is needed.

Rails 3, Rails 4

Add the gem test_after_commit to your test group in the Gemfile and you are done. You don't need to change the database strategy to deletion (wh...

Let's say you have a gem which has the following module:

module SuperClient

  def self.foo
    'Foo'
  end
  
  def bar
    'Bar'
  end

end

For reasons you need to override foo and bar.

Keep in mind: Your code quality is getting worse with with each prepend (other developers are not happy to find many library extensions). Try to avoid it if possible.

1. Add a lib/ext/super_client.rb to your project (see How to organize monkey patches in Ruby on Rails projects)
2. Add the extension, which ov...

We want to keep a changelog for all gems we maintain. There are some good practices for writing a changelog that adds value, please stick to these.

• Add a notice to the README's contribute section about the changelog
• For every release update the changelog
• Note the date format yyyy-mm-tt

What is a changelog?

A changelog is a file which contains a curated, chronologically ordered list of notable changes for each version of a project.

Why keep a changelog?

To make it easier for users and...

At makandra, we've built a few gems over the years. Some of these are quite popular: spreewald (> 1M downloads), active_type (> 1M downloads), and geordi (> 200k downloads)

Developing a Ruby gem is different from developing Rails applications, with the biggest difference: there is no Rails. This means:

• no defined structure (neither for code nor directories)
• no autoloading of classes, i.e. you need to require all files yourself
• no active_support niceties

Also, their scope...

Having a unique selector for an element is useful to later select it from JavaScript or to update a fragment with an Unpoly.

Haml lets you use square brackets ([]) to generate a unique class name and ID from a given Ruby object. Haml will infer a class attribute from the given object's Ruby class. It will also infer an id attribute from the given object's Ruby class and #id method.

This is especially useful with ActiveRecord instances, which have a persisted #id and will hence **generate the same selector o...

Why secure-only cookies used to be necessary

Cookies have an optional secure flag. It tells the browser to not send the cookie for a non-https request.

It used to be important to activate the secure flag even on sites that automatically redirect users from http:// to https://. The reason was that most users will only enter a scheme-less domain like makandra.de into their location bar, which will default to `http://m...

If you want to fill in textareas with multiple lines of text (containing line breaks / new lines) you can use Cucumber's docstrings:

And I fill in "Comment" with:
  """
  This is a long comment.
  With multiple lines.

  And paragraphs.
  """

The step definition is part of the spreewald gem

On some machines, installing Ruby 1.8.7 with ruby-build can lead to this error:

math.c:37:13: error: missing binary operator before token "("

Try instead to install ruby-1.8.7-p374.

Ruby has this handy block shortcut map(&:to_i) for map { |x| x.to_i }. However, it is limited to argument-less method invocations.

To call a method with an argument, you usually need to use the full block form. A common and annoying case is retrieving values from a list of hashes (imagine using a JSON API):

users = [ { name: 'Dominik', color: 'blue' }, { name: 'Stefan', color: 'red'} ]
names = users.collect do |user|
  user[:name]
end

If you're using Rails 5+, this example is covered by Enumerable#pluck (`users.pluck(:name)...

Whenever is a Ruby gem that provides a nicer syntax for writing and deploying cron jobs.

Leading zeros are important for whenever if you use the 24-hours format!

This schedule.rb:

every 1.day, at: '3:00', roles: [:primary_cron] do
  runner 'Scheduler.delay.do_things'
end

will lead to this crontab entry (crontab -l) with the default configuration:

0 15 * * * /bin/bash -l -c 'cd /var/www/my-project/releases/20180607182518 && bin/rails runner -e production '\''Scheduler.delay.do_things'\'''

Which would run on 3...

To catch all possible exceptions from a network call, we need to rescue many error classes like this:

rescue SocketError, Errno::ECONNREFUSED, Errno::ECONNRESET, Errno::ECONNABORTED, Errno::EHOSTUNREACH, OpenSSL::SSL::SSLError, MyHttpLib::BadResponse

You can shorten this a bit by rescuing SystemCallError, which is a base class for all Errno:: exceptions:

rescue SocketError, SystemCallError, OpenSSL::SSL::SSLError, MyHttpLib::BadResponse

Some high-level ...

When you need to store structured data (like Ruby hashes) in a single database column with ActiveRecord, a simple way is to use PostgreSQL's jsonb columns. ActiveRecord will automatically serialize and deserialize your Hash to and from JSON, and you can index JSON paths for fast reads.

As an alternative, ActiveRecord::Store offers a way to store hashes in a single database column. This card will show you how to migrate those hashes in an ActiveRecord::Migration by example:
...

Just like Ruby Gems tag their version releases to the corresponding Git commit, it can be helpful to track production deploys within the commit history. This task does the tagging for you.

Capistrano 3

# lib/capistrano/tasks/deploy.rb
namespace :deploy do
  ...

  desc 'Tag the deployed revision'
  task :tag_revision do
    date = Date.today.to_s

    puts `git tag deploy-#{date} #{fetch :current_revision}`
    puts `git push --tags origin`
  end

end

# config/deploy/production.rb
after 'deploy:finished', 'deploy:tag_revi...

Recent Bundler (1.16.1) started complaining about missing dependencies in the Gemfile. This is due to a stricter handling of specifications (see attached link).

The error message looks like this:

Downloading example-gem-1.2.3 revealed dependencies not in the API or the lockfile (other-gem (< 3)).
Either installing with `--full-index` or running `bundle update example-gem` should fix the problem.

However, bundle install --full-index did not any better for me, and bundle update is not always a viable solution.

Easiest solut...

This might be a known issue with Rubygems 2.5.1. This will help:

gem update --system