CarrierWave comes with some RSpec matchers which will make testing more comfortable. Let's say you have an Uploader like this: class MyUploader < CarrierWave::Uploader::Base include CarrierWave::MiniMagick
...different versions of your uploaded files: version :small do process resize_to_fill: [100, 100] end version :medium do process resize_to_fit: [200, nil] end version :large do
...a global variable in Rails? Ugh, that's the worst. If you need global state, you've probably reached for Thread.current. When you're using Thread.current, you must make sure...
...yourself or your cached data will stay in Thread.current. For Sidekiq, you can use request_store-sidekiq. Cronjobs are unaffected, as a new process is created each time...
...library => Google Drive) CLI tricks every developer should know Install the tldr tool using sudo apt install tldr. You can then get usage examples for every console command, e.g. tldr...
...ssh to get examples for the ssh command. (If there are no entries, run tldr -u and try again) Exercises Basic commands Experiment and do something useful with the following...
...Learn to create test data effectively using factories. Decouple tests by having each test start with an empty database and create only the records needed for the test. Learn
...with every test. In our experience the use of fixtures can make a test suite hard to work with. In any non-trivial test suite there will be thousands of...
...been released just a few days ago, allowing us to use Webpack 4. I successfully upgraded an existing real-world Webpack 3 application. Below are notes on everything that I...
Note that we prefer not using the Rails asset pipeline at all and serving all assets through Webpack for the sake of consistency. Preparations Remove version locks in Gemfile...
When your Rails application server raises error, Capybara will fail your test when it clears the session after the last step. The effect is a test that passes all steps...
...behavior will help you to detect and fix errors in your application code. However, sometimes your application will explode with an error outside your control. Two examples: A JavaScript library...
Learn to treat files as an ActiveRecord attribute type, like :string or :integer Research Look at the README for the carrierwave gem Read about Common mistakes when storing file...
...the form where we can also fill in title, year, etc. On the movie show view, render a poster version that is 400 pixel wide, with a height that respects...
...just barely wider than the container it should fit into, and it wraps a single word to a new line and it's not really pretty? Cry no more, for...
...in some browsers. When browsers encounter a text-wrapping element with text-wrap: balance style, they will try breaking to a new line sooner, if it balances out the width...
Detecting if a Javascript is running under Selenium WebDriver is super-painful. It's much easier to detect the current Rails environment instead. You might be better of checking against...
...the name of the current Rails environment. To do this, store the environment name in a data-environment of your . E.g., in your application layout: <html data-environment=<%= Rails.env %>>
...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...
If you have slow views (Haml/Partials can be slow), consider caching them. Remove code & sql-queries that are not needed to render the page. Calling to_a blindly on...
If you want to switch to another ruby versions, you have several options, depending on what you want: Do you want to switch temporarily, per project, or globally?
Unlike RVM, rbenv does not offer a command like rvm use. By default, it respects your project's .ruby-version file. If you need to change manually...
...in the context of our application. While you could roll out a custom authentication solution, this would likely expose you to the various risks of "homegrown crypto". In practice we...
...like clearance or devise for this task. Learn Read the article Rails Authentication from Scratch You don't need to do write any code, but you should be able to...
git shortlog -s -n [commit-range] -n, --numbered Sort output according to the number of commits per author -s, --summary Suppress commit descriptions, only provide commit count [commit-range]
...tagname.. for "everything after that tag" Example output for spreewald: 60 Tobias Kraze 12 Henning Koch 7 Dominik Schöler 6 Thomas Eisenbarth 5 Martin Straub 3 Minh Hemmer...
While it might seem trivial to implement an invoice that sums up items and shows net, gross and vat totals, it actually involves a lot of rules and caveats. It...
...examples in Ruby and MySQL, the concepts apply to all programming languages and data stores. When to round There are exactly two spots where your invoice logic should round money...
Intel CPUs receive updates, including security relevant upgrades, through 2 channels: Firmware/UEFI BIOS updates can also update the microcode in CPUs. This is the preferred and persistent way
How to install an microcode update? If one is available and deemed sufficiently stable from Debian's or Ubuntu's perspective, the intel-microcode package is updated and...
Are My Indexes Affected? If your database has been created on an operating system with glibc version < 2.28 and later upgraded to an operating system with glibc >= 2.28, you...
...affected. To find out which indexes in our database are affected, run the following slightly modified query from the PostgreSQL documentation: CREATE extension amcheck; SELECT bt_index_check(index => c.oid...
...good thing. It's possible to configure this requirement at the web- or proxy server level, where nginx or apache will just redirect every request on http to https. Some...
...if the URL they've been called with contains the http or the https scheme and issue their own redirect response (usually 301 or 302) to https. This card is...
Don't sum up columns with + in a sql-query if NULL-Values can be present. MySQL and PostgreSQL cannot sum up NULL values with the + value. The sum value...
MySQL: mysql> select 1 + 2 + 3; +-----------+ | 1 + 2 + 3 | +-----------+ | 6 | +-----------+ 1 row in set (0,00 sec) mysql> select 1 + NULL + 3; +--------------+ | 1 + NULL + 3 | +--------------+ | NULL...
Since I use this a lot in my daily work and there were no scripts working properly for me, I made one myself. It's actually not bound to Xfce...
...t tried it, though). Installation If you don't yet have xdotool, install it: sudo apt-get install xdotool If you don't yet have wmctrl, install it:
When you use method_missing to have an object return something on a method call, always make sure you also redefine respond_to_missing?. If you don't do it...
def method_missing(method_name, *args, &block) if method_name == :bark 'woof!' else super end end end This will allow you to say: Dog.new.bark => "woof!" But: Dog.new.respond_to? :bark...
...popup on all browsers. When you integrate a date picker popup, remember to also set autocomplete="off" on the text input that opens the calendar on click. Otherwise the autocomplete...
...suggestions will cover the calendar box and make it unusable: If you are using a tool like Unpoly you might want to set autocomplete="off" in the JavaScript that also...
If the project team consists of at least 2 members, do a daily standup. It should not take much longer than 15 minutes. Format Tell everyone else
if there are new developments everyone needs to know about A "still working on X, will probably be done today" is totally fine. No need to tell...
You can change which branches will be pushed when saying git push. Our recommendation is to set it to current. From the git-config documentation: push.default Defines the action git...
...branch, but forgot to setup tracking. If you can't currently push, use git branch --set-upstream-to=origin/$(git branch --show-current...
Du weißt was copy-on-write ist und warum das in Zusammenhang mit Snapshots praktisch ist Du weißt was Fragmentierung ist und wann und wo es bedeutsam ist
Du weißt wie du einen Datenträger verschlüsselst Du weißt wie man ein Linux System verschlüsselt Du weißt wie man die Systeme jeweils wieder entschlüsselt Inhalte LinuxFilesystemsExplained (Achtung alt)