Using git fixup helps you to speed up appending changes further back in the git history of your feature branch.

Example:

git commit --fixup aabbcc # Create a commit with the message "fixup! Commit message of aabbcc"
git rebase -i --autosquash master

It would be nice if you could use this feature without the -i flag, but until now it seems not to be possible. Read more about our recommended git workflow for feature branches.

Also have a look at [git shortcut to use git fixup](https://makandracards.com/makand...

Ubuntu has a package mysql-sandbox that lets you install multiple MySQL versions into your user home:

1. Install mysql-sandbox

sudo apt install mysql-sandbox

2. Download the version of MySQL you want to use from mysql.com:
   https://dev.mysql.com/downloads/file/?id=480427
   Make sure to choose "Generic Linux" instead of "Ubuntu" so you get a .tar.gz instead of .deb

3. cd into the directory the mysql binaries will be extracted to

mkdir -p ~/bin/sandbox_dist
cd ~/bin/sandbox_dist

4. Build the sandbox

make_sandbo...

Sometimes it is useful to define a named scope by implementing a static method with the scope's name on the scoped class. For instance, when a method should decide which existing scope should be the next link in the scope chain. Take this class for example:

class Meal < ActiveRecord::Base

  named_scope :for_date, lambda { |date| :conditions => { :date => date }}
  named_scope :with_meat, :conditions => { :meat => true }
  named_scope :without_meat, :conditions => { :meat => false }

  def self.suitable_for(user)
    if user.vegetar...

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...

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...

Chrome allows you to throttle the Network and the CPU. Both settings are useful to measure the performance of you application and reproduce performance issues (Example Debugging frontend performance issues with Chrome DevTools).

You find the settings in: DevTools > Performance > Capture Settings (Gear icon in the right corner) > `CPU: No...

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...

By default, Devise redirects to a sign-in form when accessing a route that requires authentication. If for some reason you do not want this, but use Basic Authentication (and the corresponding browser username/password dialog) instead, this is a simple change.

Note that Devise's default configuration actually only redirects requests for HTML content (as requested by the HTTP Accept header).
For all other formats (like JSON) it would use Basic Auth if the http_authenticatable setting was enabled. So you can simply enable that flag and cl...

Code comments allow for adding human readable text right next to the code: notes for other developers, and for your future self. You can imagine comments as post-its (or sometimes multi-sheet letters ...) on real-world objects like cupboards, light switches etc.

As always, with power comes responsibility. Code comments can go wrong in many ways: they may become outdated, silently move away from the code they're referring to, restate the obvious, or just clutter files.

Good Comments

Here are some simple rules to keep your comments help...

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.

In applications without a sign-up, user accounts are usually created by an admin. This imposes two challenges:

• How to transmit the password securely and
• How to make the user change the initial password immediately

There is a simple solution: create the account with a secret password, then ask the user to use the password reset with his user name.

After loading a staging dump into development, you might get an ActiveRecord::EnvironmentMismatchError when trying to replace the database (like rails db:drop, rails db:schema:load).

$ rails db:drop
rails aborted!
ActiveRecord::EnvironmentMismatchError: You are attempting to modify a database that was last run in `staging` environment.
You are running in `development` environment. If you are sure you want to continue, first set the environment using:

        bin/rails db:environment:set RAILS_ENV=development

Starting with R...

Sometimes it's nice to have some coloring in your logs for better readability. You can output your logs via tail and pipe this through sed to add ANSI color annotations (which your console then interprets).

To print a log (e.g. rails log) and color all lines containing "FATAL" in red and all lines with "INFO" in green:

tail -f /path/to/log | sed --unbuffered -e 's/\(.*INFO.*\)/\o033[32m\1\o033[39m/' -e 's/\(.*FATAL.*\)/\o033[31m\1\o033[39m/'

Here are the ...

To find an input with the type hidden, you need to specify the type hidden:

find_field('Some label', type: :hidden)

Otherwise you will see an exception :

find_field('Some label')
# => Capybara::ElementNotFound: Unable to find field "Some label" that is not disabled`.

Note: Usually you don't need to check the input of hidden fields in an integration test. But e.g. waiting for a datepicker library to write the expected value to this field before continuing the test, which prevents flaky tests, is a valid use case.

If you need to test some HTML, e.g. an embed code, you can use RubyMine's "scratch files":

1. File > New Scratch File (or Ctrl + Shift + Alt + Ins)
2. Select "HTML" as file type
3. Write or paste the HTML
4. Move your mouse to the upper right corner of the scratch file editor. Pick a browser to instantly open your file.

You can use the CSS property mask-image to define an "alpha channel" for an element.

E.g. to let an element start at full opacity at the top and gradually fade into transparency at the bottom:

.box {
  -webkit-mask-image: linear-gradient(to bottom, black 0%, transparent 100%);
  mask-image: linear-gradient(to bottom, black 0%, transparent 100%);
}

• A fully opaque black pixel will render the masked pixel fully opaque
• A fully transparent black pixel will render the ...

jQuery offers many different methods to move a selection through the DOM tree. These are the most important:

$element.find(selector)
Get the descendants of each element in the current set of matched elements, filtered by a selector. Does not find the current element, even it matches. If you wanted to do that, you need to write $element.find(selector).addBack(selector).

$element.closest(selector)
Get the first ancestor el...

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...