"Open-source software (OSS) is great. Anyone can use virtually any open-source code in their projects."

Well, it depends. Licenses can make things difficult, especially when you are developing closed-source software. Since some OSS licenses even require the employing application to be open-sourced as well (looking at you, GPL), you cannot use such software in a closed-source project.

To be sure on this, we have developed a project-level integration of Pivotal's excellent [license_finder](https:/...

Nokogiri is great. It will even fix invalid HTML for you, like a browser would (e.g. move block elements out of parents which are specified to not allow them).

>> Nokogiri::HTML.fragment("<h1><p>foo</p><span>bar</span></h1>").to_s
=> "<h1></h1><p>foo</p><span>bar</span>"

While this is mostly useful, browsers are actually fine with a bit of badly formatted HTML. And you don't want to be the one to blame when the SEO folks complain about an empty <h1>.

To avoid said behavior, use Nokogiri::XML instead of Nokogiri::HTML whe...

TL;DR PostgreSQL handles Rails 4+ text and string columns the same. Some libraries may still reflect on the column type and e.g. render differently sized text fields.

PostgreSQL offers three character types for your columns:

• character varying(n) (also called varchar or just string): Contents are limited to n characters, smaller contents are allowed.
• character(n): All contents are padded with spaces to allocate exactly n characters.
• text: There is no upper or lower character limit (except for the absolute...

In a web application you sometimes have tasks that can not be processed during a request but need to go to the background.
There are several gems that help to you do that, like Sidekiq or Resque.

With newer Rails you can also use ActiveJob as interface for a background processing library. See here for a list of supported queueing adapters.
For ...

An unresponsive service can be worse than a down one. It can tie up your entire system if not handled properly. All network requests should have a timeout.

Here’s how to add timeouts for popular Ruby gems. All have been tested. You should avoid Ruby’s Timeout module. The default is no timeout, unless otherwise specified. Enjoy!



Speaker today is Henning Koch, Head of Development at makandra.

This talk will be in German with English slides.

Introduction

As web developers we work with JavaScript every day, even when our backend code uses another language. While we've become quite adept with JavaScript at a basic level, I think many of us lack a deep understanding of the JavaScript object model and its capabilities.

Some of the questions we will answer in this talk:

• How does the new keyword construct an object?
• What is the differen...

tl;dr

Don't forget require 'English' if you use a named global such as $LAST_MATCH_INFO. Otherwise this could result in an annoying bug.

With Ruby's build-in library English you can reference global variables with an english name. This makes you code easier to read and is also suggested by Rubocop's Style/GlobalVars cop.

Example before:

if 'foo' =~ /foo/
  puts $~[1] # => foo
end

Example af...

We use the whenever gem to automatically update the crontab of the servers we deploy to. By default, whenever will update all servers with a matching role (we use the :cron role ).

This card describes how to install some tasks only for a given Rails environment or for a given Capistrano stage ("deployment target").

Installing jobs only for a given Rails environment
-----------------------------------...

In case you want to use pry with an older version of Ruby, you can try the following configurations.

Ruby 1.8.7

Your pry version must not be greater than 0.9.10.

gem 'pry', '=0.9.10'
gem 'ruby-debug', '=0.10.4'
gem "ruby-debug-pry", :require => "ruby-debug/pry"
gem 'pry-nav'
gem 'ruby18_source_location'

Ruby 1.9.3

Your pry version must not be greater than 0.9.9.

gem 'debugger', '=1.1.4'
gem 'pry-debugger', '=0.2.0'
gem 'pry', '=0.9.9'

Known errors

No source for ruby-1...

Ruby and Rails have several methods for creating a new object that looks like another: clone, dup, deep_dup. When using them you should be aware of their differences so that you can select the method you really need.

clone

• Shallow copy: references to other objects/values are copied (instead of cloning those objects/values)
• Clones the object and all its "special object attributes" like frozen, tainted and modules that the object has been extended with
• [Ruby 2.6 documentation for clone](https://devdocs.io/ruby~2.6/obj...

You can install rubygems 3.0.8 (released on February 18, 2020) to keep all the Gem::Specification#rubyforge_project deprecation warnings away from your development log. With Rubygems >= 3.1 this deprecation warning was introduced. While maintaining older projects this could get quite annoying and the fix below might okey, for newer projects the right ways is to upgrade the gems.

gem update --system 3.0.8

Example message:

NOTE: Gem::Specification#rubyforge_project= is deprecated with no replacement. It will be removed o...

You can run bundle install in parallel. This might be helpful for development, where you often install many new gems when switching between projects.

1. Find out the number of processors you have:

lscpu

2. Set the config in your ~/.bundle/config globally (replace 8 with your number of proccessors):

bundle config jobs 8

Note

If you suspect parallel execution for bundling issues, you can try serially with bundle install --jobs 1.

When you have many changes, and you want to spread them across different commits, here is a way to stage all changes matching a given regular expression for a single commit.

Example

Consider the following git diff output.

diff --git a/file1.rb b/file1.rb
index 806ca88..36d536b 100644
--- a/file1.rb
+++ b/file1.rb
@@ -1,7 +1,5 @@
-# Here is a useless comment.
-# It will be removed.
 class File1
-  def foo
+  def bar
     # ...
   end
 end
diff --git a/file2.rb b/file2.rb
index 550e1c6..600f4e3 100644
--- a/file2.rb
+++ b/file2...

The linked GitHub repository is a bit like our "dev" cards deck, but groomed from a single person (Josh Branchaud). It includes an extensive list of over 900 TILs on many topics that might be interesting for most of us. (e.g. Ruby, Rails, Git, Unix..)

Ruby

Here is an excerpt of all the Ruby TILs that were new to me. I encourage you to take your time to skim over the original list as well!

• Assoc For Hashes
  • `Hash#ass...

With puma you can have concurrent requests. There are two concepts on how Puma can handle two incoming requests: Workers and Threads.

Workers

Puma can have multiple workers. Each worker is a process fork from puma and therefore a very heavy instance and can have multiple threads, that handle the incoming requests.

Example: A Puma server with 2 workers and 1 thread each can handle 2 request in parallel. A third request has to wait until the thread of one of the workers is free.

Threads

Rails is thread-safe since version 4 (n...

Simplecov is a code coverage tool. This helps you to find out which parts of your application are not tested.

Integrating this in a rails project with rspec, cucumber and parallel_tests is easy.

1. Add it to your Gemfile and bundle

   group :test do
     gem 'simplecov', require: false
   end
   

2. Add a .simplecov file in your project root:

   SimpleCov.start 'rails' do
     # any custom configs like groups and filters can be here at a central place
     enable_cov...
   

"Everything in Ruby is an object". This is also true for nested hashes and arrays. If you copy a hash with #clone or #dup and you modify the copy, you will run into the following behavior:

original_hash = { foo: { bar: 'original value' } }
copied_hash = original_hash.dup
copied_hash[:foo][:bar] = 'changed value'

original_hash # => { foo: { bar: "changed value" }

This is, because { bar: 'baz' } is an object, which is referenced in :foo. The copy of original_hash still holds the reference to the same object, so alterin...

A recent patch level Ruby update caused troubles to some of us as applications started to complain about incompatible gem versions. I'll try to explain how the faulty state most likely is achieved and how to fix it.

Theory

When you deploy a new Ruby version with capistrano-opscomplete, it will take care of a few things:

• The new Ruby version is installed
• The Bundler version stated in the Gemfil...

Intro

Embedding videos on a website is very easy, add a <video> tag to your source code and it just works. Most of the time.

The thing is: Both the operating system and Browser of your client must support the container and codecs of your video. To ensure playback on every device, you have to transcode your videos to one or more versions of which they are supported by every device out there.

In this card, I'll explore the available audio and video standards we have right now. The goal is to built a pipeline that...

Ruby's Net::HTTP library repeats a failing request once, as long as it deems it idempotent (GET, HEAD etc). Both requests will use the configured timeout. Hence, if both requests time out, Net::HTTP will only return after twice the configured timeout.

This can become an issue if you rely on the timeout to strike precisely.

TLS/SSL certificates are often used for HTTPS traffic. Occasionally a service may also use their TLS certificate to support public-key encrypting data (e.g. when it is part of the URI and visible to the user, but contains sensitive information).

Here is how to easily fetch such certificate data.

certificate = Net::HTTP.start('example.com', 443, use_ssl: true) { |http| http.peer_cert }
# => #<OpenSSL::X509::Certificate: subject=#<OpenSSL::X509::Name CN=www.example.org,...>

certificate.public_key
# => #<OpenSSL::PKey::RSA:0x...

The linked article has a great explanation how to to deal with string encodings in Ruby. Furthermore you can check out some of our cards about encoding:

• Ruby's default encodings can be unexpected
• How to fix invalid byte sequence in UTF-8 error

This is a personal post-mortem analysis of a project that was mainly build to provide a REST API to mobile clients.

For the API backend we used the following components:

• Active Model Serializer (AMS) to serializer our Active Record models to JSON.
• JSON Schema to test the responses of our server.
• SwaggerUI to document the API.

It worked

The concept worked really good. Here are two points that were extraordinary compared to normal Rails project with many UI components:

• Having a Rails application, that has no UI components (only...