Debouncing a method call delays its execution until after a specified time has passed.
If it's called again before that time has passed, its execution is delayed again.

This technique is commonly used to improve performance when code would be run more often than it needs to.
One example for that are scroll event handlers in JavaScript: You want to react to a user scrolling, but it's enough to do that when they have stopped scrolling.

Here is a small JavaScript function that you can use for that:

function debounce(callback...

You might know a few examples, where you configure some library via a block. One example is the Rails configuration:

Rails.application.configure do |config|
  config.enable_reloading = false
end

This card describes a simple example on how to make your ruby library configurable.

Example

module FooClient
  class Client
    class_attribute :config

    def self.configure
      self.config ||= Configuration.new
      yield(config)
    end

    def test
      uri = URI.parse(FooClient::Client.config.endpoint)
      Net:...

This cards describes an example with a Github Client on how to keep your Rails application more maintainable by extracting domain independent code from the app/models folder to the lib/ folder. The approach is applicable to arbitrary scenarios and not limited to API clients.

Example

Let's say we have a Rails application that synchronizes its users with the Github API:

.
└── app
    └── models
        ├── user
        │   ├── github_client.rb
        │   └── sychronizer.rb
        └── user.rb

In this example the app folder ...

Fresh Chrome installations now show a "Choose your search engine" popup in Europe. This might make your Cucumber tests fail.

Fortunately there is a flag to disable the popup. Add the following option to your chromedriver setup code:

options.add_argument('--disable-search-engine-choice-screen')

I found this flag in Peter Beverloo's list.

Background: This was experienced locally with google-chrome 127.0.6533.72. In CI I did not get the popup.

This card is a short summary on different ways of assigning multiple attributes to an instance of a class.

Using positional parameters

Using parameters is the default when assigning attributes. It works good for a small number of attributes, but becomes more difficult to read when using multiple attributes.

Example:

class User
  def initialize(salutation, first_name, last_name, street_and_number, zip_code, city, phone_number, email, newsletter)
    @salutation = salutation
    @first_name = first_name
    @last_name = last_nam...

I used two lab days to read the The framework field guide - Fundamentals, the first of a three part series to learn the basics of frontend technologies. I can highly suggest it for learning the fundamentals. 'The framework field guide' is written by Unicron Utterances and there side has many high quality articles on web development and computer science related to programming.

[The Framework Field Guide](https://unicorn-ut...

When you mocked method calls in RSpec, they are mocked until the end of a spec, or until you explicitly release them.

You can use RSpec::Mocks.with_temporary_scope to have all mocks applied inside a block to be released when the block ends.
Example:

RSpec::Mocks.with_temporary_scope do
  allow(Rails).to receive(:env).and_return('production'.inquiry)
  puts Rails.env # prints "production"
end
puts Rails.env # prints "test"

Note that, when overriding pre-existing mocks inside the block, they are not reverted to the previously ...

tl;dr

Do not use the option optional on association declarations with a symbol, lambda or proc.

Explanation

Association declarations like belongs_to support the option optional. This option does not support symbols, lambdas or procs. If you do so, this will always result in optional: true. So your records can miss a presence validation if optional is used with a symbol, lambda or proc.

If you set t...

As we're switching from PT to Linear, I've updated the existing bash script to work for commits that are referencing Linear IDs.

A core benefit of our convention to prefix commits by their corresponding issue ID is that we can easily detect commits that belong to the same issue. You can either do that manually or use the bash script below. It can either be placed in your .bashrc or a...

If an view spec crashes due to undefined helper methods, you can enable this option:

# config/application.rb
config.action_controller.include_all_helpers = true

If you cannot use this setting, your spec can include individual helper modules like this:

describe 'some view', type: :view do
  helper SomeHelper
  helper OtherHelper

  it 'renders' do
    render 'view_that_uses_helpers'
  end
end

Alternatively you can also explicitly include *all help...

Raising errors for required and permitted attributes makes it easier to find errors in your application during development and in tests. Consider this approach if you want to strengthen the params handling in your application.

Example

# config/application.rb

config.action_controller.action_on_unpermitted_parameters = :raise

def user_params
  params.require(:user).permit(:full_name)
end

Effects

• This raises an error `Ac...

This card describes four variants, that add a more intuitive workflow when working with nested attributes in Rails + Unpoly:

1. Without JS
2. With HTML template and JS
3. With HTML template and JS using dynamic Unpoly templates
4. Adding Records via XHR and JS

Example

For the following examples we use a simple data model where a user has zero or more tasks.

When making requests using the http gem you might want to automatically follow redirects to get the desired response. This is supported but not the default behavior.

You can do so by using the .follow method.
This follows redirects for the following status codes: 300, 301, 302, 303, 307, 308

response = HTTP.get('https://www.example.com/redirect')
response.status # => 302
response.uri.to_s # => "https://www.example.com/redirect"

response = HTTP.follow.get('https://www.example.com/redirect')
response.status # => 200
response....

tl;dr When browsers start to adapt proposals from Open UI, it might not be necessary to use any 3rd party libraries to have nice components and controls in web applications e.g. selects. It would require only a minimum of CSS and Javascript to get them working and looking good.

The purpose of the Open UI, a W3C Community Group, is to allow web developers to style and extend built-in web UI components and controls, such as <select> dropdowns, checkboxes, radio buttons, and date/color pickers.

To do that, we’ll need to fully speci...

This card describes different flavors for concatting HTML safe strings in a helper method in Rails. You might want to use the tag helper instead of the content_tag helper (the tag helper knows all self closing tags).

Example

We want to generate HTML like this:

<h1>Navigation</h1>
<ul>
  <li>Left</li>
  <li>Right</li>
</ul>

Below you ca...

HTML <video> elements can automatically start playing when the autoplay attribute is set on them. Except for when they can not, e.g. on pageload, or when the element enters the DOM without user interaction, or when the browser for some other reason decided to not start playing the video.

While there is no native "autoplay failed" event to listen to, you can wait for video data to be loaded and then check if the video actually started playing.

Example

<video autoplay>
  <source src="example.mp4" type="video/mp4" />
</video>
...

Debugging performance issues in your Rails app can be a tough challenge.

To get more detailed insights consider using the rack-mini-profiler gem.

Setup with Unpoly

Add the following gems:

group :development do
  gem 'memory_profiler'
  gem 'rack-mini-profiler'
  gem 'stackprof'
end

Unpoly will interfere with the rack-mini-profiler widget, but configuring the following works okayish:

// rack-mini-profiler + unpoly
if (process...

There are two ways a logout in SAML can happen: Service Provider (SP) initiated and Identity Provider (IDP) initiated logout. I'll explain how to implement both flows with devise_saml_authenticatable.

Note

SAML also supports a SOAP and an Artifact binding to do this. This guide only refers to POST and Redirect bindings. devise_saml_authenticatable does not support SOAP and Artifact bindings.

SP initiated logout (using the Redirect Binding)

When the user clicks on Logout within the app, the app can trigger...

Note

Using rem only ever makes sense when the root font size is dynamic, i.e. you leave control to the user. Either by a) respecting their user agent defaults, or by b) offering multiple root font sizes in your application.

By defining @media queries in rem, they will accommodate to the root font size of your page. At a larger root font, breakpoints will be at larger widths, scaling with the font. However, there is a catch in case b) mentioned in the note above.

Relative length units in media queries are based on the initial value,...

Developing or debugging SAML functionality can be a hassle, especially when you need to go back and forth with someone external who is managing the identity provider (IDP).
But you can setup a local keycloak server to act as your IDP to play around with. This might seam intimidating, but is actually quite simple when using docker and turning off some verification steps.

1. Start a keycloak instance using docker

`mkdir -p keycloak_data && docker run --network=host -e KEYCLOAK_ADMIN=admin -e KEYCLOAK_ADMIN...

If you need to make an HTTPS connection to a host which uses an expired certificate, do not disable certificate verifications entirely. Doing that enables e.g. man in the middle attacks.
If you accept only a single expired and known certificate, you are much less in trouble.

Setup

All the solutions described below use a verify_callback for the request's OpenSSL::X509::Store where you can specify a lambda to adjust its verification response.
Your callback must return either true or false and OpenSSL's verification result is...

tl;dr

Prefer request specs over end-to-end tests (Capybara) to joyfully test file downloads!

Why?

Testing file downloads via Capybara is not easy and results in slow and fragile tests. We tried different approaches and the best one is just okay.

Tests for file downloads via Capybara ...

• ... are slow,
• ... are fragile (breaks CI, breaks if Selenium driver changes, ...),
• ... need workarounds for your specia...

10.0.0 2024-03-07

Compatible changes

• console command: You can now globally disable the IRB multiline feature by setting irb_flags: --nomultiline in ~/.config/geordi/global.yml. All configured irb_flags are automatically passed on to the console IRB.
• console command: Ctrl + C now properly exits a local Rails console
• rspec and cucumber commands: Run specs even if the automatic chromedriver update fails
• Improve detection of IRB version
• Add new hints to 'Did you know'

Breaking changes

• dump command: Drop...