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...

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...

Or: How to avoid and refactor spaghetti code

Please note that I tried to keep the examples small. The effects of the methods in this card are of course much more significant with real / more complex code.

What are the benefits of more modular code?

Code is written once but read often (by your future self and other developers who have to understand it in order to make changes for example). With more modular code you reduce the scope of what has to be understood in order to change something. Also, naming things gives you the opportunity t...

I recently noticed that better_errors allows you to to open files from within your favorite editor. However it was not so easy to get rubymine:// links to work on Gnome/Linux. Here is how it finally worked for me:

Step 1: Add a Desktop launcher

Add this file to ~/.local/share/applications/rubymine.desktop:

[Desktop Entry]
Version=1.0
T...

Debugging your integration tests, that run a headless Chrome inside a docker image, is tricky.

In many cases you can connect your Chrome to a remote docker container like docker-selenium, which should be the preferred way when you try to inspect a page within your integration test.

Otherwise you might be able to start your docker container with --net=host and access your local chromedriver in the host address space host.docker.internal.

If both options above don't work for you here is a...

Localizing a non-trivial application can be a huge undertaking. This card will give you an overview over the many components that are affected.

When you are asked to give an estimate for the effort involved, go through the list below and check which points are covered by your requirements. Work with a developer who has done a full-app localization before and assign an hour estimate to each of these points.

Static text

• Static strings and template text in app must be translated: Screens, mailer templates, PDF templates, helpe...

PostgreSQL, unlike MySQL, treats strings as case sensitive in all circumstances.

This includes

• comparison with = and LIKE
• collision detection in unique indexes

Usually this is fine, but some strings (like emails and usernames) should typically be treated as case insensitive.

There are a few workarounds available:

• use the citext extension (not recommended)
• use ILIKE instead of LIKE
• use Postgres' lower() function
• add an index on lower(email)

Probably th...

If you want to prevent that two processes run some code at the same time you can use the gem with_advisory_lock.

What happens

1. The thread will wait indefinitely until the lock is acquired.
2. While inside the block, you will exclusively own the advisory lock.
3. The lock will be released after your block ends, even if an exception is raised in the block.

This is usually required if there is no suitable database row to lock on.

Example

You want to generate a...

Within Capybara you most certainly use the #check- and #uncheck-method to (un)check checkboxes.
But there's one problem, if you want to test a custom styled checkbox, which hides its <input>-Tag:

• The methods cannot (un)check checkboxes without an visible <input>.
• The error message will be something like: Unable to find visible checkbox "Some label" that is not disabled

Solution 1

Use the keyword argument allow_label_click: true within the method call.
So instead of check('Some label'), use `check('Some label', allow...

Looking at the source code of the validates_numericality_of validator, it becomes clear that it converts the attribute in question to either an integer or float:

if configuration[:only_integer]
  unless raw_value.to_s =~ /\A[+-]?\d+\Z/
    record.errors.add(attr_name, configuration[:message] || ActiveRecord::Errors.default_error_messages[:not_a_number])
    next
  end
  raw_value = raw_value.to_i
else
 begin
    raw_value = Kernel.Float(raw_val...

We often have a separate production branch that lags a bit behind the more cutting edge main branch. Sometimes you want to move some, but not all commits from main to production. This can be done with a git cherry-pick.

However, this may lead to considerable pain later, since git does not understand the commits are actually "the same". Hazards are unnecessary and hard to resolve conflicts as well as incorrect auto-merges.

In order to avoid this, always merge the production branch back to the main after the cherry-pick. Even t...

Be careful when using buttons without a type attribute, since browsers will consider them the default submit button of a form.

Suppose you have this form:

<form action="/save">
  <input type="text" />
  <button onclick="alert('Alert!')">Alert</button>
  <button type="submit">Save</button>
</form>

If you press the enter key inside in the text input, browsers will trigger the first button and show the alert.

To fix this, add a type="button" attribute to the first button.

Rack::SteadyETag was a Rack middleware that generates the same default ETag for responses that only differ in XOR-masked CSRF tokens or CSP nonces.

We have deprecated Rack::SteadyETag. We instead recommend reconfiguring your Rails app so two requests to the same resource produce the same HTML for a given user.

Every Rails response has a default ETag header. In theory this would enable caching for multiple requests to the same resource. Unfortunately the default ETags produced by Rails are effectively random, meaning they can never match a future request.

Understanding ETags

When your Rails app responds with ETag headers, future requests to the same URL can be answered with an empty response if the underlying content ha...

CoffeeScript and JavaScript (ECMAScript) both have operators in and of. Each language use them for more than one purpose. There is not a single case where the same operator can be used for the same purpose in both languages.

Check if an object (or its prototype) has a property

CoffeeScript

var hasFoo = 'foo' of object

JavaScript

var hasFoo = 'foo' in object;

Iterate through all properties of an object
================================...

Here are some popular mistakes when using nested forms:

• You are using fields_for instead of form.fields_for.
• You forgot to use accepts_nested_attributes in the containing model. Rails won't complain, but nothing will work. In particular, nested_form.object will be nil.
• The :reject_if option lambda in your accepts_nested_attributes call is defined incorrectly. Raise the attributes hash given to your :reject_if lambda to see if it looks like you expect.
• If you are nesting forms into nested forms, each model involved ne...

Test-Driven Development (TDD) in its most dogmatic form (red-green-refactor in micro-iterations) can be tedious. It does not have to be this way! This guide shows a pragmatic approach with integration and unit tests, that works in practice and improves on productivity.

Advantages

• No added effort: tests need to be written anyway.
• Test heads serve as todo lists. You'll always know what is finished and what is left to do.
• Big tasks are broken down into smaller tasks that can be processed one by one.
• You will not forget a test.

T...

tl;dr

Individual transform properties are great because they allow you to write more readable and maintainable CSS, especially when applying multiple transformations and/or when animating transforms.

For ages, CSS transforms had to be defined using the transform property. For a single transformation, this was something like transform: scale(1.5), and multiple transformations could be applied by chaining them.

.example {
  transform: scale(1.5) rotate(45deg) translateY(-50%);
}

All modern browsers (Chrome & Edge ...

tl;dr

asdf allows you to manage multiple runtime versions with a single CLI tool and is backwards compatible by supporting existing config files, like e.g. .nvmrc or .ruby-version.

Getting Started

1. Disable rbenv
   1.1 Delete or comment out source /home/$user/.rbenvrc in ~/.profile
   1.2 Delete or comment our eval "$(rbenv init -)" in ~/.bashrcor~/.zshrc`
   1.3 To take effect you may have to restart your shell or log out and log in again from your current linux session
2. Install asdf by following the official [...