4018 cards

Components: Dynamically growing input field's height to fit content

Sometimes you will need an input field which wraps content and grows in height as soon as content gets longer than the input fields width.
There is no way to get a "normal" string input field to wrap as desired, but there are other ways.

Here is one pretty easy solution to get what you want:

Step 1

Let your input became a text area with one row.

f.text_area(:name, rows: 1, autosize: '') 

Step 2

Include the autosize Archive library in your project

yarn add autosize

And make your...


How to Work With Time Zones in Rails

With different time zones

When dealing with time zones in Rails, there is one key fact to keep in mind:

Rails has configurable time zones, while
Ruby is always in the server's time zone

Thus, using Ruby's time API will give you wrong results for different time zones.

For consistency, you should only use Rails' methods, but the hard thing is to know which method originates from Ruby and which from Rails. To simplify this, adhere to the following suggestion:

Use Time.zone for everything time-related

# Examp...
Linked content

Casting ActiveRecord scopes or instances to ActiveType extended model classes

When working with ActiveType you will often find it useful to cast an ActiveRecord instance to its extended ActiveType::Record variant.

Starting with active_type 0.4.0 Archive you can use ActiveType.cast for this:

class User < ActiveRecord::Base

class SignUp < ActiveType::Record[User]

user = User.find(1)
sign_up = ActiveType.cast(user, SignUp)
sign_up.is_a?(SignUp) # => true

This is basically like [ActiveRecord#becomes](http://apidock.com/rails/v4.2.1/ActiveRecord/Pers...


Ruby: Replacing Unicode characters with a 7-bit transliteration

Using ActiveSupport

ActiveSupport comes with a #transliterate method which replaces characters with their low-ASCII equivalent (to strip accents etc.:):

ActiveSupport::Inflector.transliterate('aäoöuü') # => "aaoouu"

You can also add custom rules in your I18n dictionary like this:

        Ä: 'Ae'
        Ö: 'Oe'
        Ü: 'Ue'
        ä: 'ae'
        ö: 'oe'
        ü: 'ue'
        ß: 'ss'

With this you get:


Jasmine: Testing if two arrays contain the same elements

When the order matters:


Regardless of order:


Ignoring extra elements:


Version 5 of the Ruby Redis gem removes Redis.current

Redis.current will be removed without replacement in redis-rb 5.0.
Version 4.6.0 adds deprecation warnings for Redis.current and Redis.current=:

`Redis.current=` is deprecated and will be removed in 5.0.

If your application still uses Redis.current, you can only fix it by no longer using it. Here is how.

Redis.new when you need it

You can easily instantiate a Redis client when you need it.

There is probably already a constant like REDIS_URL that you use to configure Sidekiq or similar. So just use that one.



Authorize allowed values with assignable_values

All our projects have enum-like requirements like this:

  • An attribute value must be included in a given set of values.
  • The list of allowed values must be retrievable in order to render <select> boxes.
  • Each value has a humanized label.
  • Sometimes there is a default value.

Most of the time, this requirement is also needed:

  • The list of assignable values depends on the user who is currently signed in.

In our past projects there are many different solutions for these related requirements, e.g. ChoiceTrait, methods like `available_...


Matching unicode characters in a Ruby (1.9+) regexp

On Ruby 1.9+, standard ruby character classes like \w, \d will only match 7-Bit ASCII characters:

"foo" =~ /\w+/   # matches "foo"
"füü" =~ /\w+/   # matches "f", ü is not 7-Bit ASCII

There is a collection of character classes that will match unicode characters. From the documentation:

  • /[[:alnum:]]/ Alphabetic and numeric character
  • /[[:alpha:]]/ Alphabetic character
  • /[[:blank:]]/ Space or tab
  • /[[:cntrl:]]/ Control character
  • /[[:digit:]]/ Digit
  • /[[:graph:]]/ Non-blank character (excludes spaces, co...

Carrierwave: How to attach files in tests

Attaching files to a field that is handled by a Carrierwave uploaders (or maybe any other attachment solution for Rails) in tests allows different approaches. Here is a short summary of the most common methods.

You might also be interested in this card if you see the following error in your test environment:

You tried to assign a String or a Pathname to an uploader, for security reasons, this is not allowed.
If this is a file upload, please check that your upload form is multipart encoded.


How to access Chrome Devtools when running JavaScript tests via CLI

While we are used to run our JavaScript tests on a test page within our Browser, it's also possible to run them on the command line with NodeJS. I think that's actually the most common way to run JS tests.

Given a Vue project that uses Jest (via vue-cli-service) with the following package.json:

  "scripts": {
    "test": "vue-cli-service test:unit --testMatch='**/tests/**/*.test.js' --watch"

This allows us to run J...

Jest: How to clear the cache

I recently was in a weird situation where my (Jest/CLI) tests were referencing a function that was no longer part of my code - I had just refactored it.

Apparently Jest has some kind of cache that caused the issue, running npx jest --clearCache solved it for me.

RSpec: You can super into parent "let" definitions

RSpec's let allows you to super into "outside" definitions, in parent contexts.


describe '#save' do
  subject { described_class.new(attributes) }
  let(:attributes) { title: 'Example', user: create(:user) }

  it 'saves' do
    expect(subject.save).to eq(true)

  context 'when trying to set a disallowed title' do
    let(:attributes) { super().merge(title: 'Hello') } # <==

    it 'will not save' do
      expect(subject.save).to eq(false)

I suggest you don't make a habit of using this regula...

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Ruby blocks: Braces and do/end have different precedence

TL;DR {} binds stronger than do … end (as always in Ruby, special characters bind stronger than words)


Right way

names = ['bRUce', 'STaN', 'JOlIE']

# Blocks in braces are passed to the rightmost method
print names.map { |name| name.downcase }
print(names.map do |name| name.downcase end) # equivalent
=> ["bruce", "stan", "jolie"]

Wrong way

Avoid the examples below, as you pass at least one block to print and not to the enumerator.

names = ['bRUce', 'STaN', 'JOlIE'] 

# Blocks in do…end are passed to t...
Linked contentRepeats

Testing HTTPS with badssl.com

Website that offers lots of different kinds of HTTPS configurations, bad or good or complicated.

They also offer a dashboard Archive to check if your browser's HTTPS handling works as expected (which might be compromised e.g. due to security products or enterprise proxy servers).


Recommended git workflow for feature branches

This is a guide on how to effectively use git when working on a feature branch. It is designed to get out of your way as much as possible while you work, and ensure you end up with clean commits in the end.

We assume you are the only person working on this branch. We also assume the branch has never been "partially" merged into master.

You want to start a feature branch

git checkout master
git checkout -b my-feature-branch
git push -u origin my-feature-branch

You've added code that works ind...

Integrating ESLint


To ensure a consistent code style for JavaScript code, we use ESLint Archive . The workflow is similar to integrating rubocop for Ruby code.

1. Adding the gem to an existing code base

You can add the following lines to your package.json under devDependencies:

  "devDependencies": {
    "eslint": "^8.7.0",
    "eslint-config-standard": "^16.0.3",
    "eslint-plugin-import": "^2.25.4",
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Git: rebase dependent feature branch after squash

This card will show you how to use git rebase --onto without confusion.

Use case:

You've got two feature branches (one and two), where two depends on one. Now commits of branch one have changed after you branched two from it (i.e. after code review the commits of branch one are squashed). Thus the commit history of branch one has changed. Branch two's history however didn't change.


To make the branches share the same commit history again you will have to rebase and replay (attach) the add...

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