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Cucumber steps to travel through time with Timecop

These steps are now part of Spreewald.


Here are some useful examples how to use the attached Cucumber Timecop steps:

When the date is 2011-05-06
When the time is 2011-05-06 17:30

There is also one really awesome step that lets you travel to the past or to the future:

When /^it is (\d+|a|some) (seconds?|minutes?|hours?|days?|months?|years?) (later|earlier)$/

As you can see, you describe the *time unit amo…

Repeats

Ruby < 2.4: Downcasing or upcasing umlauts

Using .downcase or .upcase on strings containing umlauts does not work as expected in Ruby versions before 2.4. It leaves the umlauts unchanged:

"Über".downcase
=> "Über"

"Ärger".downcase
=> "Ärger"

The very same applies for french accents (Thanks Guillaume!):

"Être ou ne pas être, telle est la question".downcase
=> "Être ou ne pas être, telle est la question"

Obviously, this leads to problems when comparing strings:

"Über".downcase == "über"
=> false

In Rails you can use ActiveSupports' [multib…

Linked content

Rails' Insecure Defaults - Code Climate Blog

Rails’ reputation as a relatively secure Web framework is well deserved. Out-of-the-box, there is protection against many common attacks: cross site scripting (XSS), cross site request forgery (CSRF) and SQL injection. Core members are knowledgeable and genuinely concerned with security.

However, there are places where the default behavior could be more secure. This post explores potential security issues in Rails 3 that are fixed in Rails 4, as well as some that are still risky. I hope this post will help you secure your own apps, as w…

Linked content

CSS: Using interaction media detection to disable hover styles for devices that have no hover

Since late 2015, all major browsers (still excluding Firefox) support pointing device media queries. These can be used to distinguish e.g. coarse from fine pointers (e.g. finger vs mouse), or a device with hover support from one without (e.g. desktop with mouse vs tablet).

Motivation

When hover styles modify the DOM, most mobile devices activate the hover styles on first tap. A second tap is required to trigger a click. While this can be handy, at times it makes the UX worse.

Another issue with hover styles is that they tend to st…

Linked content

Logic in media queries

Here is how to model basic logic in media queries.

AND

With keyword and.

# Target viewport widths between 500 and 800px
@media (min-width: 500px) and (max-width: 800px)

OR

Comma-separated.

# Target viewport widths below 500 or above 800px
@media (max-width: 500px), (min-width: 800px)

NOT

Needs a little overhead with not all and.

# Target devices that can't hover
@media not all and (hover)

See CSS: Using interaction media detection on why you'd need this.

Repeats

ActiveRecord: validate_uniqueness_of is case sensitive by default

By default, validates_uniqueness_of does not consider "username" and "USERNAME" to be a collision. If you use MySQL this is probably not what you want, since string comparisons are case-insensitive in MySQL.

(If you use PostgreSQL, read this instead.)

Say you have a user model

class User < ActiveRecord::Base
  validates_uniqueness_of :name
end

with a unique index in the database.

If you try to create the users "user" and "USER", this will not trigger a validation error, but may fail with a SQL error due to d…

Repeats

Find an ActiveRecord by any column (useful for Cucumber steps)

The attached patch lets you find a record by a string or number in any column:

User.find_by_anything('carla')
User.find_by_anything('email@domain.de')
User.find_by_anything(10023)

There's also a bang variant that raises ActiveRecord::NotFound if no record matches the given value:

User.find_by_anything!('carla')

Boolean and binary columns are excluded from the search because that would be crazy.

I recommend copying the attachment to features/support/find_by_anything.rb, since it is most useful in Cucumber step …

Repeats

Concurrency issues with find-as-you-type boxes

Find-as-you-type boxes are usually built by observing changes in a text field, and querying the server via AJAX for search results or suggestions when the field has changed.

A common problem with this implementation is that there is no guarantee that AJAX responses are evaluated in the same order as the original requests. The effect for the user is that the search results are flashing back and forth while the user is typing the query, and when the user has stopped typing the last results don't always match the final query.

You won't notice…

Beware: Don't name a controller action "cookies"

The method cookies is defined in the ActionController and should never be overwritten.

Bad example

class StaticPagesController < ApplicationController

  def imprint
  end

  def cookies
    redirect_to '/'
  end

end

If you create an action called cookies, any call to the cookie storage will be broken and call the method. What's more, in this example calls to static_pages_controller#imprint might as well end up redirecting to the homepage.

Solution

Just define the action as cookies_action or similar and adjust…

ActiveRecord::Store: migrate data in store

When you need to store structured data (like Ruby hashes) in a single database column with ActiveRecord, a simple way is to use PostgreSQL's jsonb columns. ActiveRecord will automatically serialize and deserialize your Hash to and from JSON, and you can index JSON paths for fast reads.

As an alternative, ActiveRecord::Store offers a way to store hashes in a single database column. This card will show you how to migrate those hashes in an ActiveRecord::Migration by example: …

Repeats

How to make your application assets cachable in Rails

Note: Modern Rails has two build pipelines, the asset pipeline (or "Sprockets") and Webpacker. The principles below apply for both, but the examples shown are for Sprockets.


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 probabl…

Repeats

MySQL: CONCAT with NULL fields

In MySQL,

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

the NULL always wins in MySQL.

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

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

PostgreSQL

In PostgreSQL the NULL is not viral in CONCAT:

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

Disable automatic code suggestions in RubyMine

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

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

Repeats

Rails Authentication Checklist

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…

Rails: Disabling logging entirely

In an environment:

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

Printing background color of elements

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;

Capistrano + Rails: Tagging production deploys

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…

Linked content

Capistrano + Rails: Automatically skipping asset compilation when assets have not changed

In medium-sized to large Rails applications, asset compilation can take several minutes. In order to speed up deployment, asset precompilation can be skipped. This card automates the process.

Capistrano 3

```
namespace :deploy do

desc 'Automatically skip asset compile if possible'
task :auto_skip_assets do
asset_locations = %r(^(Gemfile.lock|app/assets|lib/assets|vendor/asset))

revisions = []
on roles :app do
  within current_path do
    revisions << capture(:cat, 'REVISION').strip
  ...
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