TL;DR Still has caveats.
Code splitting is a feature of JavaScript bundlers that can keep huge libraries out of the main bundle.
Like Webpack esbuild lets you use the await import() function to load code on demand:
// application.js
const { fun } = await import('library.js')
fun()
However, esbuild's code splitting is disabled by default. The code above would simply [inline](https://en.wiki...
You can use rake --where task to find the source location that defines task:
bundle exec rake --where assets:precompile
rake assets:precompile /home/henning/.rbenv/versions/2.6.6/lib/ruby/gems/2.6.0/gems/precompiled_assets-0.2.1/lib/precompiled_assets/tasks/assets.rake:5:in `block in <main>'
Debugging your integration tests, that run a headless Chrome inside a docker image, is tricky.
In many cases you can connect your Chrome to a remote docker container like docker-selenium, which should be the preferred way when you try to inspect a page within your integration test.
Otherwise you might be able to start your docker container with --net=host and access your local chromedriver in the host address space host.docker.internal.
If both options above don't work for you here is a...
The rubocop binary has a few interesting flags:
rubocop (using the --parallel default ) scans the current repository for linting issues while using multiple CPU coresrubocop -a (or --autocorrect) safely corrects most offenses while doing a sequential scan
rubocop -A (or --autocorrect-all) also tries to correct unsafe suggestionsAutocorrection takes significantly longer on large projects because of the sequential nature.
To speed things up, you can use the following alias. It first checks in parallel if any files...
Every Rails response has a default ETag header. In theory this would enable caching for multiple requests to the same resource. Unfortunately the default ETags produced by Rails are effectively random, meaning they can never match a future request.
When your Rails app responds with ETag headers, future requests to the same URL can be answered with an empty response if the underlying content ha...
tl;dr
asdfallows you to manage multiple runtime versions with a single CLI tool and is backwards compatible by supporting existing config files, like e.g..nvmrcor.ruby-version.
source /home/$user/.rbenvrc in ~/.profileeval "$(rbenv init -)" in ~/.bashrcor~/.zshrc`When you use native smooth scrolling there is no built-in method to detect the end of the scrolling animation. Methods like scrollTo() don't return a promise. We will eventually get a scrollend event, but that is still some time away.
Until then I'm using the following `awaitScrollE...
By activating strict_loading you force developers to address n+1 queries by preloading all associations used in the index view. Using an association that is not preloaded will raise an ActiveRecord::StrictLoadingViolationError.
I think it's a good default to activate strict_loading in your controllers' #index actions. This way, when a change introduces an n+1 query, you...
Since Ruby 3.2.0 you can measure coverage support for eval statements and support has been added for the simplecov gem as well.
This allows to track coverage across ruby templates such as haml, erb, ...
Simply set this within simplecov
SimpleCov.start do
enable_coverage_for_eval
end
SASS has an @extend keyword to inherit styles.
.alert
color: red
&.-framed
border: 1px solid red
padding: 5px
&.-homepage
@extend .-framed
border-width: 5px
When compiling, SASS will simply join the selectors. Note how .-homepage is written where .-framed was defined:
...
.alert.-framed, .alert.-homepage {
border: 1px solid red;
padding: 5px;
}
.alert.-homepage {
border-width: 5px;
}
Warning
Unfortunately, this does...
If you use a newer SSH key generated with the ED25519 algorithm instead of RSA (see Create a new SSH key pair), the deployment with Capistrano may fail with the following message:
The deploy has failed with an error: unsupported key type `ssh-ed25519'
net-ssh requires the following gems for ed25519 support:
* ed25519 (>= 1.2, < 2.0)
* bcrypt_pbkdf (>= 1.0, < 2.0)
See https://github.com/net-ssh/net-ssh/issues/565 for more information
Gem::LoadError : "ed25519 i...
In the past we validate and set default values for boolean attributes in Rails and not the database itself.
Reasons for this:
An alternative approach, which currently reflects more the general opinion of the Rails upstream on constraints in the database, is adding default values in the schema of the database itself. We also ...
Sometimes I ran across a GitHub merge request of a gem where it was not completely obvious in which version the change was released. This might be the case for a bugfix PR that you want to add to your project.
Git can help you to find the next git tag that was set in the branch. This usually has the name of the version in it (as the rake release task automatically creates a git tag during release).
git name-rev --tags <commit ref>
Note
The more commonly used
git describecommand will return the last tag before a c...
After upgrading to Rails 6.1.7.2 one of our apps printed a wall of warnings while booting:
/var/www/app/shared/bundle/ruby/2.6.0/gems/net-protocol-0.2.1/lib/net/protocol.rb:68: warning: already initialized constant Net::ProtocRetryError
/home/deploy-app/.rbenv/versions/2.6.10/lib/ruby/2.6.0/net/protocol.rb:66: warning: previous definition of ProtocRetryError was here
/var/www/app/shared/bundle/ruby/2.6.0/gems/net-protocol-0.2.1/lib/net/protocol.rb:214: warning: already initialized constant Net::BufferedIO::BUFSIZE
/home/deploy-app/.rben...
Bundler so far ignored the version specified under BUNDLED_WITH in the Gemfile.lock. This had two annoying consequences:
Gemfile.lock, you got an error message and had to manually install the correct version.Gemfile.lock, bundler silently updated the version in the Gemfile.lock to your system's bundler version. To avoid this, you had to always specify, which version you want to use for each bundler c...Timecop is a great gem to set the current time in tests. However, it is easy to introduce flakyness to your test suite when you forget to reset the time after the test.
This might be the case if:
Often you only notice these kinds of errors in rare cases when tests are executed in a particular order.
A way to avoid this is by using block notation (`Timecop.travel(...) ...
In a Jasmine spec you want to spy on a function that is imported by the code under test. This card explores various methods to achieve this.
We are going to use the same example to demonstrate the different approaches of mocking an imported function.
We have a module 'lib' that exports a function hello():
// lib.js
function hello() {
console.log("hi world")
}
export hello
We have a second module 'client' that exports a function helloTwice(). All this does is call hello() ...
We usually rely on VCR and WebMock to prevent any real network connection when running our unit tests.
This is not entirely true: They are both limited to a set of HTTP libraries listed below (as of 2022). Direct calls to Kernel#open or OpenURI#open_uri are not mocked and will trigger real network requests even in tests. This might bite you e.g. in [older versions of CarrierWave](https://github.com/carrierwaveuploader/carrierwave/blob/0.11-stable/lib/carrierwave/upl...
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)>
If that's actually the case, then you can try to deprioritize the ipv...
Greg Molnar has written a neat article about creating a single-file Rails app.
This is not meant for production use but can be useful to try things out, e.g. when hunting down a bug or embedding a Rails app into the tests of a gem.
What you do is basically:
.ru file, like app.ru.rackup app.ru. (Hint: if your file is called config.ru, you can just run `rac...Sometimes the need arises for SSL in local development. We have guides for different webservers, this one is for puma.
make sure mkcert is installed
create an SSL certificate for localhost with mkcert:
$ mkcert-v1.4.4-linux-amd64 localhost
Created a new local CA 💥
...
config/puma.rb:localhost_key = "#{File.join('localhos...
Note
Use
yarn dedupein Yarn v2+: https://yarnpkg.com/cli/dedupe
This package only works with Yarn v1. Yarn v2 supports package deduplication natively!
A duplicate package is when two dependencies are resolved to a different version, even when a single version matches the range specified in the dependencies. See the Deduplication strategies section for a few examples.
Yarn is stupid, so it can happen that there are several version of the same package in your bundle, although one would fulf...
When your Rails application offers downloading a bunch of files as ZIP archive, you basically have two options:
This card is about option 2, and it is actually fairly easy to set up.
We are using this to generate ZIP archives with lots of files (500k+) on the fly, and it works like a charm.
Offering downloads of large archives can be cumbersome:
This should be fixed in the latest LTS-branches of our mysql2 fork, 0.2.x-lts and 0.3.x-lts.
Use
gem 'mysql2', git: 'https://github.com/makandra/mysql2', branch: '0.2.x-lts' # for Rails 2.x
gem 'mysql2', git: 'https://github.com/makandra/mysql2', branch: '0.3.x-lts' # for Rails 3.x
in your Gemfile, and do a
bundle update mysql2
mysql2 used to check that the client library used at runtime actually matches the one it was compiled against. However, at least on Ubunt...