So you downloaded inaction_mailer, and you had a folder full of e-mails generated while writing your app?

Easily show multiple, overlapping events across calendar days and rows.

A simple implementation of an Identity Mapper for Active Record.

Unfortunately vanilla Ruby modules lack support for many idioms popular in modern Ruby. Most importantly, we have become accustomed to composing our classes with meta-programming macros such as has_many, validates_presence_of or after_save. And modules weren't built with macros in mind.

Steak is like Cucumber but in plain Ruby.

Rack middleware for rate-limiting incoming HTTP requests.

File upload solution that supports form roundtrips when a validation fails.

Here is a set of additive color model conversion algorithms that I found published on Wikipedia and have implemented in JavaScript.

We recently decided our CI server needed an overhaul. I really enjoyed Integrity as a build server, but after trying out Hudson it’s hard to say I want to go back. Hudson has several huge advantages.

What do we expect from the custom finder? We expect that it should find assets A, B, C and should not find assets D, E, F. And sometimes the order is important: it should find A, B C with exact order.

All ActiveRecord associations except for has_many :through support callbacks for pre- and post-insertion/deletion via the following, self-documenting parameters:

"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:/...

By default, Rails views escape HTML in any strings you insert. If you want to insert HTML verbatim, you need to call #html_safe. However, #html_safe does not "unescape" a string. It merely marks a string as safe for unescaped insertion.

How html_safe works

Calling html_safe on a String returns a new object that looks and acts like a String, but actually is a ActiveSupport::SafeBuffer:

"foo".length
# => 3
"foo".class
# => String

"foo".html_safe.length
# => 3
"foo".html_safe.class
# => ActiveSupport::S...

Database connections are not thread-safe. That's why ActiveRecord uses a separate database connection for each thread.

For instance, the following code uses 3 database connections:

3.times do
  Thread.new do
    User.first # first database access makes a new connection
  end
end

These three connections will remain connected to the database server after the threads terminate. This only affects threads that use ActiveRecord.

You can rely on Rails' various clean-up mechanisms to release connections, as outlined below. This may...

ActiveStorage does not provide any built-in way of implementing authentication for the available DirectUpload endpoint in Rails. When using DirectUpload as JS wrapper in the frontend, be aware that its Rails endpoint is public by default, effectively allowing anyone to upload an unlimited amount of files to your storage.

The DirectUploadController from @rails/activestorage bypasses your form controller because it uploads the file using an AJAX request that runs directly, before any form roundtrip happens. This is a comfortable solutio...

When localizing model attributes via I18n you may run into errors like this:

I18n::InvalidPluralizationData: translation data { ... } can not be used with :count => 1. key 'one' is missing.

They seem to appear out of the blue and the error message is more confusing than helpful.

TL;DR A model (e.g. Post) is lacking an attribute (e.g. thread) translation.
Fix it by adding a translation for that model's attribute (attributes.post.thread). The error message reveals the (wrongly) located I18n data (from `attributes.thread...

Rails' url_for is useful for generating routes from a Hash, but can lead to an open redirect vulnerability.

Your application's generated route methods with a _url suffix are also affected because [they use url_for unter the hood](https://github.com/rails/rails...

To allow HTTP 304 responses, Rails offers the fresh_when method for controllers.

The most common way is to pass an ActiveRecord instance or scope, and fresh_when will set fitting E-Tag and Last-Modified headers for you. For scopes, an extra query is sent to the database.

fresh_when @users

If you do not want that magic to happen, e.g. because your scope is expens...

A flaky test is a test that is often green, but sometimes red. It may only fail on some PCs, or only when the entire test suite is run.

There are many causes for flaky tests. This card focuses on a specific class of feature with heavy side effects, mostly on on the UI. Features like the following can amplify your flakiness issues by unexpectedly changing elements, causing excessive requests or other timing issues:

• Lazy loading images
• Autocomplete in search f...

When working with custom transactions and use ActiveRecord::Rollback you may encounter unexpected behaviour if you try to roll back your changes.

tl;dr

When using nested transactions, ActiveRecord::Rollback might not do what you expect, since it will only roll back the inner, but not the outer transaction.

You can fix this behavior by using transaction(joinable: false) but this leads to a bunch of different problems.

When you don't need an explicit ActiveRecord::Rollback, don't worry about any of this and just use a plan `tran...