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CucumberFactory 2.0.1 released

CucumberFactory 2.0.1 fixes an issue with multiline assignments.

2.0.1 - 2020-02-27

Compatible changes

Fix a bug that prevented created records to be named when using multiline attribute assignments

Given "Bob" is a user with these attributes:
  | email |     |
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How to use the Capistrano 2 shell to execute commands on servers

Capistrano 2 brings the shell command which allows you to run commands on your deployment targets.
There is also invoke to run a command directly from your terminal.

Both commands allow running Capistrano tasks or shell commands, and scope to individual machines or machine roles.

Unfortunately Capistrano 3 does not include these commands any more.

cap shell


First of all, spawn a Capistrano shell (we're using the multistage extension here):

$ cap staging shell

In your "cap" shell you can now run Capistrano ta…


Escape a string for transportation in a URL

To safely transport an arbitrary string within a URL, you need to percent-encode characters that have a particular meaning in URLs, like & or =.

If you are using Rails URL helpers like movies_path(:query => ARBITRARY_STRING_HERE), Rails will take care of the encoding for you. If you are building URLs manually, you need to follow this guide.


In Ruby, use CGI.escape:

=> "foo%3Dfoo%26bar%3Dbar"

Do not ever use URI.encode or …

How to make a cucumber test work with multiple browser sessions

Imagine you want to write a cucumber test for a user-to-user chat. To do this, you need the test to work with several browser sessions, logged in as separate users, at the same time.

Luckily, Capybara makes this relatively easy:


Scenario: Alice and Bob can chat
Given Alice, Bob, and a chat session
When I am signed in as "Alice"
And I go to the chat
And I am signed in as "Bob" [session: bob]
And I go to the chat [session: bob]
And I send the message "Hello, this is Alice!"
Then I should see "Hello, this …

Rails: Rest API post-mortem analysis

This is a personal post-mortem analysis of a project that was mainly build to provide a REST API to mobile clients.

For the API backend we used the following components:

  • Active Model Serializer (AMS) to serializer our Active Record models to JSON.
  • JSON Schema to test the responses of our server.
  • SwaggerUI to document the API.

It worked

The concept worked really good. Here are two points that were extraordinary compared to normal Rails project with many UI components:

  • Having a Rails application, that has no UI components (only…

How to: Validate dynamic attributes / JSON in ActiveRecord

PostgreSQL and ActiveRecord have a good support for storing dynamic attributes (hashes) in columns of type JSONB. But sometimes you are missing some kind of validation or lookup possibility (with plain attributes you can use Active Record's built-in validations and have your schema.rb).

One approach about being more strict with dynamic attributes is to use JSON Schema validations. Here is an example, where a project has the dynamic attributes analytic_stats, that we can use to store analytics from an external measurement tool.

  • A g…
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Structuring Rails applications: the Modular Monorepo Monolith

Root Insurance runs their application as a monolithic Rails application – but they've modularized it inside its repository. Here is their approach in summary:


  • Keep all code in a single repository (monorepo)
  • Have a Rails Engine for each logical component instead of writing a single big Rails Application
  • Build database-independent components as gems
  • Thus: gems/ and engines/ directories instead of app/
  • Define a dependency graph of components. It should have few edges.
  • Gems and Engines can be extracted easier once nece…
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Updated: Migration from the Asset Pipeline to Webpacker

  • Added check for css extraction in webpacker.yml
  • Added link to Webpack(er) A primer
  • Added item 3 and 4 to the Cleanup section

Rspec: around(:all) and around(:each) hook execution order


  • around(:suite) does not exist.
  • around(:all) runs after before(:all) and before after(:all).
  • around(:each) runs before before(:each) and after after(:each).

As this is not 100% obvious (and not yet documented) it is written down in this card. In RSpec 3 :each has the alias :example and :all the alias :context.


RSpec.configure do |config|
config.before(:suite) { puts 'BEFORE :suite' }
config.after(:suite) { puts 'AFTER :suite' }

describe 'order of hook execution' do


Always convert and strip user-provided images to sRGB

Debugging image color profiles is hard. You can't trust your eyes in this matter, as the image rendering depends on multiple factors. At least the operation system, browser or image viewer software and monitor influence the resulting image colors on your screen.

When we offer our users the possibility to upload images, they will most likely contain tons of EXIF metadata and sometimes exotic color profiles like eciRGB. We want to get rid of the metadata, as it might contain sensitiv…

Understanding SQL compatibility modes in MySQL and MariaDB

MySQL and MariaDB have an SQL mode setting which changes how MySQL behaves.

The SQL mode value is comprised of multiple flags like "STRICT_TRANS_TABLES, NO_ZERO_IN_DATE". Each flag activates or disables a particular behavior.

The default SQL mode varies widly between versions of MySQL and MariaDB. In general, more recent versions of MySQL and MariaDB have stricter settings than older versions, and MySQL has stricter settings than the more liberal MariaDB.

If your app explodes …


In MySQL, a zero number equals any string

In MySQL comparing zero to a string 0 = "any string" is always true!

So when you want to compare a string with a value of an integer column, you have to cast your integer value into a string like follows:

SELECT * from posts WHERE CAST(posts.comments_count AS CHAR) = '200' 

Of course this is usually not what you want to use for selecting your data as this might cause some expensive database operations. No indexes can be used and a full table scan will always be triggered.

If possible, cast the compared value in your application to…

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Effectively Using Materialized Views in Ruby on Rails · pganalyze

It's every developer's nightmare: SQL queries that get large and unwieldy. This can happen fairly quickly with the addition of multiple joins, a subquery and some complicated filtering logic. I have personally seen queries grow to nearly one hundred lines long in both the financial services and health industries.

Luckily Postgres provides two ways to encapsulate large queries: Views and Materialized Views. In this article, we will cover in detail how to utilize both views and materialized views within Ruby on Rails, and we can even take…

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A Migration Path to Bundler 2+

Bundler 2 introduced various incompatibilites und confusing behavior. To add to the confusion, Bundler's behavior changed after the release of their version 2.

The linked article explains what happened.


FileIO: Writing strings as Carrierwave uploads

When you have string contents (e.g. a generated binary stream, or data from a remote source) that you want to store as a file using Carrierwave, here is a simple solution.

While you could write your string to a file and pass that file to Carrierwave, why even bother? You already have your string (or stream).
However, a plain StringIO object will not work for Carrierwave's ActiveRecord integration:

>> Attachment.create!(file:
TypeError: no implicit conversion of nil into String

This is because Carrierwave ex…

jQuery promises: done() and then() are not the same

jQuery's deferred objects behave somewhat like standard promises, but not really.

One of many subtle differences is that there are two ways to chain callbacks to an async functions.

The first one is done, which only exists in jQuery:

$.ajax('/foo').done(function(html) {
  console.debug("The server responded with %s", html);

There is also then, which all promise libraries have:

$.ajax('/foo').then(function(html) {
console.debug("The server resp…

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Different ways to set attributes in ActiveRecord

Rails 3

Method Uses Default Accessor Mass Assignment Protection Saved to Database Validations
attribute= Yes No No n/a
write_attribute No No No n/a
update_attribute Yes No Yes …  

Common mistakes when storing file uploads with Rails

1. Saving files to a directory that is not shared between deploys or servers

If you save your uploads to a made up directory like "RAILS_ROOT/uploads", this directory goes away after every deploy (since every release gets a new). Also this directory is not shared between multiple application servers, so your uploads are randomly saved to one local filesystem or another. Fixing this afterwards is a lot of fun.

Only two folders are, by default, shared between our application servers and deployments: "RAILS_ROOT/storage" and `"RAILS…

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