Writing ruby methods that accept both optional and keyword arguments is dangerous and should be avoided. This confusing behavior will be deprecated in Ruby 2.7 and removed in Ruby 3, but right now you need to know about the following caveats.

Consider the following method

# DO NOT DO THIS

def colored_p(object = nil, color: 'red')
  switch_color_to(color)
  puts object.inspect
end


colored_p(['an array'])                   # ['an array'] (in red)
colored_p({ a: 'hash' }, color: 'blue')   # {:a=>'hash'} (in blue)
colored_p({ a: 'ha...

This can happen with a very simple model:

class Note
  has_many :attachments
end

Everything looks normal:

Note.all.to_a.size # => 8
Note.all.ids.size # => 8

Then .includes leads to weird results:

Note.all.includes(:attachments).to_a.size # => 8
Note.all.includes(:attachments).ids.size # => 12

If a note has 5 attachments, its id will be included 5 times.

With .preload it works as expected:

Note.all.preload(:attachments).to_a.size # => 8
Note.all.preload(:attachments).ids.size # => 8

Note

I crea...

Large Rails projects tend to define multiple custom ways to format Dates or DateTimes. This often leads to duplicated format strings, wrong formats and unnecessary introduction of new formats.

to_fs also supports to refer to those formats by name e.g. to_formatted_s(:iso_8601) or to_formatted_s(:short).
to_fs is an alias for to_formatted_s.

Those names are defined in Time::DATE_FORMATS and it's possible to add your own formats. There is a how to in the official [docs](https://api.rubyonrails.org/classes/Date.html#method-i-t...

tl;dr

The Chrome DevTools are a neat collection of tools for the daily work as a web developer. If you're lucky, you'll maybe find some handy stuff in here.

Analysing

• Frontend Performance Issues
• Rendering Performace

Breakpoints

• [Breakpoints on HTML Elements](https://makandracards.com/makandra/517982-chrome-devtools...

sass >= 1.35.0 has the option quietDeps and silenceDeprecations to silence deprecation warnings from dependencies.

• quietDeps: No deprecation warnings for dependencies e.g. Bootstrap
• silenceDeprecations: Allows to set a list of deprecation types you want to silence for your own code

Below there are a few examples for different build tools how to set the Sass options.

Webpacker

const sassLoaderConfig = environment.loaders.get('sass')
const...

CSS transitions are a simple animation framework that is built right into browsers. No need for Javascript here. They're supported by all browsers.

Basic usage

Transitions are used to animate the path between to property values. For example, to let the text color fade from red to green on hover, the following SASS is used (shorthand syntax):

.element
  color: red
  transition: color .1s
  
  &:hover
    color: green

This tells the browser "whenever the color of an .element changes...

If you ever wondered why a constant wasn't defined or wasn't available where you expected it to be, this article will help.

Also see Ruby constant lookup: The good, the bad and the ugly.

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...

When writing a Sass function, you may run into an error message that may be confusing:

@function rules may not contain style rules.

What Sass is trying to tell you is that a line in your Sass function is computing a result that is neither assigned to a variable nor returned.

Keep in mind that all functions in Sass return something, Sass does not mutate objects.

tl;dr

In Chrome DevTools in the Sources tab you can activate Event Listener Breakpoints for debugging events.

Example

The Event Listener Breakpoints in the Chrome DevTools can be quiet useful for debugging why and where code is handling specific events.

Here you can see a very simple example that shows what lines of code handle a click:

You can use this Code Pen if you want to try it yourself.

Limitation

...

tl;dr

In Chrome DevTools in the Elements tab or in Firefox in the Inspector tab you can right click on an element and choose Break on to debug changes related to this element.

Example

DOM Breakpoints can be quite useful to quickly find the JavaScript that is responsible for some (unexpected) behavior. You can use DOM Breakpoints for debugging subtree modifications, attribute modifications or node removal.

Here you can see a very simple example that shows what JavaScript lines are responsible for ...

Simply add this to your .rspec instead:

--require spec_helper

If you are on rspec >= 3 and use a rails_helper.rb require this instead of the spec_helper:

--require rails_helper

If you are using parallel_tests and this is not working for you, .rspec might be ignored. Try using a .rspec_parallel file.

Capybara gives you two different methods for executing Javascript:

page.evaluate_script("$('input').focus()")
page.execute_script("$('input').focus()")

While you can use both, the first line (with evaluate_script) might freeze your browser window for 10 seconds.

The reason is that evaluate_script will always return a result. The return value will be converted back to Ruby objects, which in case of complex objects (e.g. a jQuery collection) is very expensive.

Because of this we recommend to only use evaluate_script whe...

Git allows you to set push options when pushing a branch to the remote.
You can use this to build an alias that automatically pushes a branch and creates a merge request for it.

Put this in your ~/.gitconfig in the [alias] section:

mr = push origin HEAD -o merge_request.create -o merge_request.draft

Now you can do git mr and a draft merge request will be created.
Target branch is your project's default branch, i.e. main or master.

To specify a different target branch, add -o merge_request.target=other-branch.

[There...

tl;dr

In the Elements tab in the Chrome DevTools you can right click on an element and select Store as global variable.

Example

Git allows you to do a binary search across commits to hunt down the commit that introduced a bug.

Given you are currently on your branch's HEAD that is not working as expected, an example workflow could be:

git bisect start # Start bisecting
git bisect bad # Tag the revision you are currently on (HEAD) as bad. You could also pass a commit's SHA1 like below:
git bisect good abcdef12345678 # Give the SHA1 of any commit that was working as it should
# shorthand:
git bisect start <bad ref> <good ref>

Git will fetch a comm...

As your Rails project grows, you will accumulate a number of small patches. These will usually fix a bug in a gem, or add a method to core classes.

Instead of putting many files into config/initializers, I recommend to group them by gem in lib/ext:

lib/
  ext/
    factory_girl/
      mixin.rb
    carrierwave/
      change_storage.rb
      fix_cache_ids.rb
      sanitize_filename_characters.rb
    ruby/
      range/
        covers_range.rb
      array/
        dump_to_excel.rb
        xss_aware_join.rb
      enumerable/
    ...

Capybara-screenshot can automatically save screenshots and the HTML for failed Capybara tests in Cucumber, RSpec or Minitest.

Requires Capybara-Webkit, Selenium or poltergeist for making screenshots. They're saved into $APPLICATION_ROOT/tmp/capybara

The attached files contain config for cucumber integration and a Then show me a screenshot step.
If your project uses Spreewald, you can use its Then show me the page step instead.

Inclu...

Background:

ActiveType::Object inherits from ActiveRecod::Base and is designed to behave like an ActiveRecord Object, just without the database persistence.

Don't remove any of the default behavior of the initialize method!

If you have a class which inherits from ActiveType::Object and you need to override the #initialize method, then you should be really careful:

• Always pass exactly one attribute. ActiveRecod::Base objects really want to get their arguments processable as keyword arguments. Don't change the syntax, or y...

The problem

If you're experiencing that your bundle install command fails with an error message like this, rubygems.org might have issues with their ipv6 connectivity:

$ bundle install
Fetching source index from https://rubygems.org/

Retrying fetcher due to error (2/4): Bundler::HTTPError Could not fetch specs from https://rubygems.org/ due to underlying error <timed out (https://rubygems.org/specs.4.8.gz)>

The (a little bit dirty) possible solution

If that's actually the case, then you can try to deprioritize the ipv...

The problem

Unpoly's [up-observe], [up-autosubmit] and [up-validate] as well as their programmatic variants up.observe() and up.autosubmit() are a nightmare for integration tests.

Tests are usually much faster than the configured up.form.config.observeDelay. Therefore, it may happen that you already entered something into the next field before unpoly updates that field with a server response, discarding your changes.

The steps I wait for active ajax requests to complete (if configured) and capybara-lockstep can catch some ...

tl;dr

Since Rails 7+ you can use ComparisonValidator for validations like greater_than, less_than, etc. on dates, numerics or strings.

Example

We have a model for booking a trip. This model has mandatory attributes to enforce dates for the start and the end.

# == Schema Information
#
# start_date :date
# end_date   :date
# ...

class TripBooking < ApplicationRecord
  validates :start_date, presence: true
  validates :end_date, presence: true
end

These validations are enough. We also want to ensure, th...

Say you have a User with a Carrierwave attribute #avatar:

class User < ActiveRecord::Base
  mount_uploader :avatar, AvatarUploader
end

When whitelisting the avatar field in the controller, you might do this:

params[:user].permit(:avatar)

But you probably want this:

params[:user].permit(:avatar, :avatar_cache, :remove_avatar)

In this example:

• :avatar_cache allows a newly upload image to persist through form roundtrips in the case of validation errors (something that isn't possibl...