On some of our older projects, we use the mysql2 gem. Unfortunately, versions 0.2.x (required for Rails 2.3) and versions 0.3.x (required for Rails 3.2) can no longer be installed on Ubuntu 20.04. Trying this either leads to errors when compiling the native extension, or a segfaults when using it.
For Rails 4.2, mysql2 version 0.4.10 seems to work okay. If you still have issues, upgrade to 0.5.x, which should be compatible.
To install it, you have to switch the mysql2 gem to our fork. In your Gemfile, ...
It sometimes happen that a database dump, that would want to insert into your development database, does not match the current schema of the database. This often happens when you have an old dump, but your current setup is up to date with the the master.
Hint: In most cases it is sufficient to delete and recreate the local database in order to import the dump. If any problems occur, proceed as follows:
The sidekiq-rate-limiter gem allows rate-limiting Sidekiq jobs and works like a charm. However, it needs to be integrated on a per-worker basis.
If you want to limit a whole queue instead, and if your requirements are simple enough, you can do it via a Sidekiq middleware yourself.
Here is an example that limits concurrency of the "mailers" queue to 1. It uses a database mutex via the [with_advisory_lock](https://github.com/ClosureTree/wit...
If you're using the webdrivers gem and VCR together, depending on your configuration, VCR will yell at you regulary.
The webdrivers gem tries to update your webdrivers on your local machine. To do so, it checks the internet for newer versions, firing an HTTP-request to e.g. https://chromedriver.storage.googleapis.com
You can "fix" this in multiple ways:
Update your drivers on your machine with
RAILS_ENV=test rake webdrivers:chromedriver:update
Ignore the driver update-URL in your ...
Pagy is a gem for pagination.
They make some bold claims:
Pagy is the ultimate pagination gem that outperforms the others in each and every benchmark and comparison.
Maybe this is worth trying out.
This is an extract from the linked article. It shows an approach on how to implement encrypted passwords with the AWS Key Management Service (KMS).
For most applications it's enough to use a hashed password with a salt (e.g. the gem devise defaults to this).
Generate hash as hash of password + salt.
Encrypt the hash with a public key from KMS (you can store the public key in your server code).
In your database sto...
Rails 5.2+ supports "verbose query logs" where it shows the source of a query in the application log.
Normally, it looks like this:
User Load (0.5ms) SELECT "users".* FROM "users" WHERE ...
↳ app/controllers/users_controller.rb:42:in `load_users'
However, you may encounter ActiveRecord's LogSubscriber as the source for all/most queries which is not helpful at all:
User Load (0.5ms) SELECT "users".* FROM "users" WHERE ...
↳ activerecord (6.0.3.3) lib/active_record/log_subscriber.rb:100:in `debug'
While th...
Here is an example with the --tags option. You need to wrap them inside --cucumber-options option of parallel_cucumber.
DISPLAY=:17 bundle exec parallel_cucumber --cucumber-options '--tags @solo' features
See more details in the docs.
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
- The thread will wait indefinitely until the lock is acquired.
- While inside the block, you will exclusively own the advisory lock.
- 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.
You want to generate a...
CSP hat zum Ziel einen Browser-seitigen Mechanismus zu schaffen um einige Angriffe auf Webseiten zu verhindern, hauptsächlich XSS-Angriffe.
XSS = Cross Site Scripting. Passiert wenn ein User ungefiltertes HTML in die Webseite einfügen kann.
<div class="comment">
Danke für den interessanten Beitrag! <script>alert('you have been hacked')</script>
</div>
Rails löst das Problem weitgehend, aber
GoodJob is a new background worker gem. It's compatible with ActiveJob.
We're huge fans of Sidekiq for its stability and features. One advantage of GoodJob over Sidekiq is that GoodJob doesn't require Redis. So in cases where you don't have Redis or don't want to pay for a Redis HA quorum node, this might be an alternative worth checking out.
These warnings are printed when the etc Gem is installed, while etc is also included in Ruby. Fix with:
gem uninstall etc
"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:/...
PostgreSQL offers three character types for your columns:
character varying(n) (also called varchar or just string): Contents are limited to n characters, smaller contents are allowed.character(n): All contents are padded with spaces to allocate exactly n characters.text: There is no upper or lower character limit (except for the absolute maximum of 1 GB).The documentation states:
There is no performance difference among these three types, apart ...
In a web application you sometimes have tasks that can not be processed during a request but need to go to the background.
There are several gems that help to you do that, like Sidekiq or Resque.
With newer Rails you can also use ActiveJob as interface for a background processing library. See here for a list of supported queueing adapters.
For ...
An unresponsive service can be worse than a down one. It can tie up your entire system if not handled properly. All network requests should have a timeout.
Here’s how to add timeouts for popular Ruby gems. All have been tested. You should avoid Ruby’s Timeout module. The default is no timeout, unless otherwise specified. Enjoy!

We use CarrierWave in many of our projects to store and serve files of various formats - mostly images. A common use case of CarrierWave's DSL is to "process" the original file in order to create multiple "versions", for example different resolutions of the same image.
Now we could go one step further: What if we want to create versions that have a different file extension than the original file? For example, let's assume we'd like to create a ve...
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...
We use the whenever gem to automatically update the crontab of the servers we deploy to. By default, whenever will update all servers with a matching role (we use the :cron role ).
This card describes how to install some tasks only for a given Rails environment or for a given Capistrano stage ("deployment target").
Installing jobs only for a given Rails environment
-----------------------------------...
In case you want to use pry with an older version of Ruby, you can try the following configurations.
Your pry version must not be greater than 0.9.10.
gem 'pry', '=0.9.10'
gem 'ruby-debug', '=0.10.4'
gem "ruby-debug-pry", :require => "ruby-debug/pry"
gem 'pry-nav'
gem 'ruby18_source_location'
Your pry version must not be greater than 0.9.9.
gem 'debugger', '=1.1.4'
gem 'pry-debugger', '=0.2.0'
gem 'pry', '=0.9.9'
You can install rubygems 3.0.8 (released on February 18, 2020) to keep all the Gem::Specification#rubyforge_project deprecation warnings away from your development log. With Rubygems >= 3.1 this deprecation warning was introduced. While maintaining older projects this could get quite annoying and the fix below might okey, for newer projects the right ways is to upgrade the gems.
gem update --system 3.0.8
Example message:
NOTE: Gem::Specification#rubyforge_project= is deprecated with no replacement. It will be removed o...
You can run bundle install in parallel. This might be helpful for development, where you often install many new gems when switching between projects.
lscpu
~/.bundle/config globally (replace 8 with your number of proccessors):bundle config jobs 8
Note
If you suspect parallel execution for bundling issues, you can try serially with
bundle install --jobs 1.
The linked GitHub repository is a bit like our "dev" cards deck, but groomed from a single person (Josh Branchaud). It includes an extensive list of over 900 TILs on many topics that might be interesting for most of us. (e.g. Ruby, Rails, Git, Unix..)
Here is an excerpt of all the Ruby TILs that were new to me. I encourage you to take your time to skim over the original list as well!
With puma you can have concurrent requests. There are two concepts on how Puma can handle two incoming requests: Workers and Threads.
Puma can have multiple workers. Each worker is a process fork from puma and therefore a very heavy instance and can have multiple threads, that handle the incoming requests.
Example: A Puma server with 2 workers and 1 thread each can handle 2 request in parallel. A third request has to wait until the thread of one of the workers is free.
Rails is thread-safe since version 4 (n...