Every page in your application uses many assets, such as images, javascripts and stylesheets. Without your intervention, the browser will request these assets again and again on every request. There is no magic in Rails that gives you automatic caching for assets. In fact, if you haven't been paying attention to this, your application is probably broken in that respect and users will re-request every single image etc. on every page load.

While ETags will usually prevent the image d…

Authentication is a special part of web applications. On the one hand, it usually is a crucial security mechanism restrict access to certain people and roles. On the other hand, most users authenticate only once, so it is very unlikely to spot issues by accident.

So, here comes a quick checklist to help you verifying your authentication solution is all set.

• This should be default: use HTTPS with HSTS. The HSTS part is important.
• Use a reliable authentication solution, e.g. Clearance or [Devise…

Browsers' printing methods usually don't print background colors. In most cases this is the desired behavior, because you don't want to spent tons of ink printing the background of a web page. But in some cases you want to print the background color of elements, e.g. bars of a chart. For those elements you need to set the following css styles:

Chrome and Safari:

-webkit-print-color-adjust: exact;

Firefox:

color-adjust: exact;

This card existed before, but was outdated due to browser implementation changes. The information below is validated for the current list of browsers we support.

By default your html and body elements are only as high as the actual page content. If you only have two lines of text in your page, your html and body elements will only be around 40 pixels high, regardless of the size of your browser window.

You might be surprised by this, since setting a background on either html and body does cover the enti…

There is a kinda secret, yet well supported CSS feature called currentColor. It's like a special CSS variable that has been supported in almost all browsers for almost all time (see linked Caniuse).

Usage

The currentColor value can be used in CSS to indicate the current value of color should be used. A common use case is setting a border color:

a.ghost
  color: white
  border: 1px solid currentColor
  &:hover
    color: red // Border color will change as well 

Note that in many cases, you can simply omit the color to ac…

In MySQL,

CONCAT('foo', 'bar', NULL) = NULL

the NULL always wins. This is not true in PosgreSQL.

If you would rather treat NULL as an empty string, use CONCAT_WS (concatenation with separator) instead:

CONCAT_WS('', 'foo', 'bar', NULL) = 'foobar'

Updated title to make clear what the card is actually about.

Slightly restructured.

Just like Ruby Gems tag their version releases to the corresponding Git commit, it can be helpful to track production deploys within the commit history. This task does the tagging for you.

Capistrano 3

# lib/capistrano/tasks/deploy.rb
namespace :deploy do
  ...

  desc 'Tag the deployed revision'
  task :tag_revision do
    date = Date.today.to_s

    puts `git tag deploy-#{date} #{fetch :current_revision}`
    puts `git push --tags origin`
  end

end

```
# config/deploy/production.rb
after 'deploy:finished', 'deploy:tag_revi…

Authentication is hard: there are many edge cases, and most users (including yourself) usually only go the "happy path" once and never see the edge cases. If you have rolled your own authentication, or been using older authentication solutions, or resorted to HTTP Basic Authentication, this card will tell you what to do to make your application safe.

Any application that stores sensitive data in the browser

That is: cookies, e.g. by offering a login.

• Ask the admins to [turn on SSL](https://makandracards.com/makandra/1416-integrate-s…

Since images are magnitudes larger in file size than text (HTML, CSS, Javascript) is, loading the images of a large web page takes a significant amount of the total load time. When your internet connection is good, this is usually not an issue. However, users with limited bandwidth (i.e. on mobile) need to mine their data budget better.

One popular strategy to improve the website performance is to not load images until they enter the viewport – aka "lazy-loading images".

General Issues

• Crawlers do not execute JavaScript (generally sp…

Installing ruby 1.8.7 with rbenv might fail if you have installed libssl-dev instead of libssl1.0-dev (default in Ubuntu 18.04).

Run sudo apt install libssl1.0-dev to remove libssl-dev and add libssl1.0-dev.

You can check installed libssl packages using apt list:

```
$ apt list –installed | grep libssl

WARNING: apt does not have a stable CLI interface. Use with caution in scripts.

libssl-dev/bionic,now 1.1.0g-2ubuntu4 amd64 [installed]
libssl-doc/bionic,bionic,now 1.1.0g-2ubuntu4 all [installed,automatic]
libssl1.0.0/bion…

To disable the mostly useless automatic suggestion popups in RubyMine, go to File / Preferences, then to Editor / General / Code Completion and uncheck Autopopup code completion.

You can still open the popup by pressing CTRL + Space. And you probably want to use Context-dependent word expansion instead, anyway.

In an environment:

config.logger = Logger.new('/dev/null')

0.56.0

This release includes major performance improvements and a new animation engine.

Beware of the breaking change with .up-current!

Navigation feedback

Maintaining the .up-current on all links turned out to be a major performance bottleneck, so we had to make some breaking changes:

• The .up-current class is now only assigned to links with an [up-nav] attribute…

The problem

Calling bundle update GEMNAME will update a lot more gems than you think. E.g. when you do this:

bundle update cucumber-rails

… you might think this will only update cucumber-rails. But it actually updates cucumber-rails and all of its dependencies. This will explode in your face when one of these dependencies release a new version with breaking API changes. Which is all the time.

In the example above updating cucumber-rails will give you Capybara 2.0 (because capybara is a dependency of `cucumber-rail…

The Edge Rider gem gives your relations a method #traverse_association which
returns a new relation by "pivoting" around a named association.

Say we have a Post model and each Post belongs to an author:

class Post < ActiveRecord::Base
  belongs_to :author
end

To turn a relation of posts into a relation of its authors:

posts = Post.where(:archived => false)
authors = posts.traverse_association(:author)

You can traverse multiple associations in a single call.
E.g. t…

Add a user with password

mysql -uroot -p
CREATE USER 'newuser'@'localhost' IDENTIFIED BY 'changeme';
GRANT ALL PRIVILEGES ON * . * TO 'newuser'@'localhost';
FLUSH PRIVILEGES;
exit;

Add a user without password

mysql -uroot -p
CREATE USER 'newuser'@'localhost' IDENTIFIED BY '';
GRANT ALL PRIVILEGES ON * . * TO 'newuser'@'localhost';
FLUSH PRIVILEGES;
exit;

If you don't have a user with the sufficient access rights, follow these steps to reset…