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/
    ...

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...

tl;dr

git checkout is the swiss army of git commands. If you prefer a semantically more meaningful command for branch related tasks, use git switch instead.

You can use git switch since git 2.23.

Switch Branch

git branch
# * master
#   feature-branch

git switch feature-branch
git branch
#   master
# * feature-branch

git switch -
git branch
# * master
#   feature-branch

Info

For this use case you can of course also use git checkout.

Switch on a Remote Branch

git branch -a
# * m...

Ncdu is a disk usage analyzer with an ncurses interface. It is designed to find space hogs on a remote server where you don’t have an entire graphical setup available, but it is a useful tool even on regular desktop systems. Ncdu aims to be fast, simple and easy to use, and should be able to run in any minimal POSIX-like environment with ncurses installed.

Alternatives

• du -hs * | sort -h
• Disk Usages Analyser

By convention, common protocols use a defined port, like 80 for HTTP or 443 for HTTPS.

You can use nmap to find out what service is running behind a given port, and most often see some details about it. This can be helpful if servers don't offer the services you expect for some ports. If you'd like to see what ports are listing on your local machine, you might want to use netstat instead of nmap.

Note that nmap's service discovery may trigger several requests.

Example

When using nmap, adding the -A switch ...

If you're suffering from a huge de.yml or similiar file, cry no more. Rails lets you freely organize your dictionary files in config/locales.

My organization works like this:

• config/locales/rails.de.yml modified Rails boilerplate
• config/locales/faker.de.yml modified Faker boilerplate
• config/locales/models.de.yml model names, attribute names, assignable_value labels
• `config/locales/views.de.y...

In Active Record you can use named bindings in where-conditions. This helps you to make your code more readable and reduces repetitions in the binding list.

Example without named bindings

User.where(
  'name = ? OR email ?',
  params[:query],
  params[:query]
)

Example with named bindings

User.where(
  'name = :query OR email :query',
  query: params[:query]
)

You can use ETags to allow clients to use cached responses, if your application would send the same contents as before.

Besides what "actually" defines your response's contents, your application probably also considers "global" conditions, like which user is signed in:

class ApplicationController < ActionController::Base

  etag { current_user&.id }
  etag { current_user&.updated_at }

end

Under the hood, Rails generates an ETag header value like W/"f14ce3710a2a3187802cadc7e0c8ea99". In doing so, all objects from that etagge...

One rule of thumb I try to follow in capybara tests is using capybara matchers and not plain rspec matchers.

One example:

visit(some_page)
text_field = find('.textfield')
expect(text_field['value']).to match /pattern/

This can work, but is too brittle and flaky. match will not retry or synchronize the value of text_field.

The equivalent code with a capybara matcher:

visit(some_page)
expect(page).to have_field('.textfield', with: /pattern/)

have_field will retry for and synchronize the text_field.

This checklist should help you to check edge cases that are not part of the default Carrierwave configuration.

• Check Default Configuration and Suggested Changes
• Use secret URLs.
• Check if you need expiring public URLs.
• Check if you need an optimized cache
• Use a [nested directory structure](https://makandracards.com/m...