An alternative of using a multiple assignment for a Regex are named groups. Especially when your Regex becomes more complicates it is easier to understand and to process.

Note:

• In case a string does not match the pattern, .match will return nil.
• With Ruby 2.4 the result of .match can be transformed to a Hash with named_captures. This allows you to use methods like slice or fetch on the result.

Example with a mult...

Was ist Elastic?

• Suchmaschine, basierend auf Apache Lucene
• größtenteils Open-Source
• einige kommerzielle Features ("Elastic Stack", früher "X-Pack")
  • Zugriffsrechte (bis vor kurzen)
  • Monitoring
  • Reporting
  • Graph-Unterstützung
  • Machine Learning
• REST-Api (JSON über HTTP)

Grundlagen

Elastic antwortet per Default auf Port 9200

http GET :9200

{
  "name": "ntK2ZrY",
  "cluster_name": "elasticsearch",
  "cluster_uuid": "Bbc-ix5bQZij5vfFU29-Cw",
  "version": {
    "number": "6.7.1",
    "build_flavor": "...

PostCSS is a tool for transforming styles with JS plugins. In Webpacker you can configure the plugins and their settings via the postcss.config.js file. Make sure that postcss-loader is part of your package.json.

module.exports = {
  plugins: [
    require('postcss-import'),
    require('postcss-flexbugs-fixes'),
    require('postcss-preset-env')({
      autoprefixer: {
        flexbox: 'no-2009'
      },
      stage: 3
    })
  ]
}

Note: Stage 3 means you can use all CSS features that ar...

To avoid multiple versions of a package, you can manually maintain a resolutions section in your package.json. We recommend you to do this for packages like jQuery. Otherwise the jQuery library attached to window might not include the functions of your packages that depend on jQuery.

Note: This is only an issue in case you want to use a package functionality from window e.g. $(...).datepicker() from your dev console or any other javascript within the application.

Background

By default yarn will create a folder node_modules ...

When doing some meta-programming magic and you want to do something for all attributes of a class, you may need to access connection or some of its methods (e.g. columns) during class definition.

While everything will be fine while you are working on a project that is in active development, the application will fail to boot when the database is missing or has no tables. This means that Raketasks like db:create or db:migrate fail on a freshly cloned project.

The reason is your environment.rb which is loaded for Raketasks and calls...

This is a short overview of things that are required to upgrade a project from the Asset Pipeline to Webpacker. Expect this upgrade to take a few days even the diff is quite small afterwards.

Preparations

1. Find all libraries that are bundled with the asset pipeline. You can check the application.js and the application.css for require and import statements. The source of a library is most often a gem or a vendor directory.
2. Find an working example for each library in the application and write it down.
3. Find out the ver...

In Rails, we usually have a mailer setup like this:

class MyMailer < ActionMailer::Base

  def newsletter
    mail to: 'receiver@host.tld',
      from: 'sender@host.tld',
      subject: 'My mail'
  end

end

If you want to preview your mail in the browser, you can use the Action Mailer Preview. To inspect the mail directly in your email client, just create an .eml file and open it with your client:

mail = MyMailer.newsletter
Fil...

While deploying an Ruby update to an old application these days, we encountered the following misleading error:

*** [err :: some-host.makandra.de] You are trying to install in deployment mode after changing
*** [err :: some-host.makandra.de] your Gemfile. Run `bundle install` elsewhere and add the
*** [err :: some-host.makandra.de] updated Gemfile.lock to version control.
*** [err :: some-host.makandra.de] 
*** [err :: some-host.makandra.de] You have deleted from the Gemfile:
*** [err :: some-host.makandra.de] *

We found out a newe...

Rails' ActiveSupport::TimeWithZone objects have both a timezone code and offset, e.g. Thu, 28 Mar 2019 16:00:00 CET +01:00. Ruby's stdlib TZInfo also has time zones, but with different identifiers.
Unfortunately, not all timezone codes can be used to parse strings or to move time objects into another time zone.

Some timezone codes like CET are supported by ActiveSupport extensions like String#in_time_zone, while many codes will actually not work:

>> '2019-03-01 12:00'.in_time_zone('PST')
ArgumentError (Invalid Timezone: PST)
...

When we want to use our own (or bought) fonts in an application with Webpack(er), we have two options. We can

• put the fonts directly into your Webpack's assets folder or
• write an npm package with an own sass file that can be imported from the Webpack manifest.

Load fonts from your assets folder

The first option turns out to be straightforward: Import the stylesheets in the index.js of the pack you're using:

// webpack_source_path/application/index.js

import './stylesheets/reset'
import...

When you have a powerful machine with many CPU cores, you might run into an error like

ERR DB index is out of range (Redis::CommandError)

This is because Redis defaults to at most 16 databases (0 to 15) and running tests in parallel might exceed that (your tests might run on databases 1..n or 2..(n+1)).

You can increase that limit:

1. Get number of CPUs of your machine.

   nproc --all
   

2. Open up Redis configuration file.

   sudo vim /etc/redis/redis.conf
   

3. Find databases row and increase it, e.g. set to 32:

...

Here is how to make Rome datepicker look like the rest of your Bootstrap 4 application.

Rome comes with very little basic styling. While we could redefine its classes, we can configure the classes Rome applies to its elements to make it look like this:

Since Bootstrap 4 comes with several helpful utility classes, and requires fewer markup/containers, we can achieve Bootstrap 4 experience by applying a few classes via the styles setting.

You still need to include `ro...

Webpacker is Rails' way of integrating Webpack, and version 4 has been released just a few days ago, allowing us to use Webpack 4.

I successfully upgraded an existing real-world Webpack 3 application. Below are notes on everything that I encountered.
Note that we prefer not using the Rails asset pipeline at all and serving all assets through Webpack for the sake of consistency.

Preparations

• Remove version locks in Gemfile for webpacker
• Remove version locks in package.json for webpack and webpack-dev-server
• Install by ca...

RSpec >= 3.3 added aggregate_failures, which allows multiple failures in an example and list them all, rather than aborting on the first failure.

This can be used:

• In the global configuration
• With the tag :aggregate_failures (our preferred option in case every expectations should be aggregated)
• With the method aggregate_failures

[Here](https://web.archive.org/web/20210110131654/https://relishapp.com/rspec...

For searching in large database tables we usually use PostgreSQL's fulltext search capabilities.

While this works reasonably well for content primarily consisting of prose, it is not necessarily a good solution for all use cases. The main issue is that it is only possible to search for prefixes of text tokens, which can potentially be unexpected for users.

One example are dates:

If you index the text 2019-01-23 15:16, PostgreSQL will create the following tokens: 2019, -01, -23, 15 16. A user searching for 01-23 wi...

This is a presentation from 2019-01-21.

Summary

• We want to move away from jQuery in future projects
• Motivations are performance, bundle size and general trends for the web platform.
• The native DOM API is much nicer than it used to be, and we can polyfill the missing pieces
• Unpoly 0.60.0 works with or without jQuery

Is jQuery slow?

From: Sven
To: unpoly@googlegroups.com
Subject: performance on smartphones and tablets

Hello

I just used your framework in one project and must say,
I am really pleased with it -- but o...

Spammers have started abusing other application to send their spam. This works like this:

• The application has some form that allows to send e-mails to arbitrary users. This can be something like a newsletter sign-up with a double-opt in, a registration confirmation e-mail (or even password reset e-mail), or something similar.
• The e-mail also includes some reflected text. For example, a user may be able to give their name, and the name is used within the e-mail. The spammer will then abuse that text to include his advertisment.

Potentia...

When restoring a PostgreSQL dump using pg_restore, you usually add the --clean flag to remove any existing data from tables.

Note that this only removes data from tables that are part of the dump and will not remove any extra tables. You need to do that yourself.

When is this relevant?

As an example: You want to load a staging dump into your development machine. On your development machine, you have run migrations that introduced more tables which do not yet exist on staging. pg_restore with --clean will loa...

When building an application that sends e-mails to users, you want to avoid those e-mails from being classified as spam. Most obvious scoring issues will not be relevant to you because you are not a spammer.

However, your application must do one thing by itself: When sending HTML e-mails, you should include a plain-text body or tools like SpamAssassin will apply a significant score penalty. Here is how to do that automatically.

1. Add premailer-rails to your Gemfile and bundle.
2. Done! ...

The standard way to abort async code is that your function takes a AbortSignal { signal } property. The caller can use this signal to send an abort request to your function. Upon receiving the request, your function should reject its promise with an error.

Async browser functions like fetch() reject their promises with a new DOMException('Message here', 'AbortError') when canceled.

This already has good browser support and can be polyfilled on older browsers.

Exa...

When doing Basic Authentication, your browser will send an "Authorization" header. Its value is simply a Base64-encoded representation of "username:password" (like when you place credentials in the URL directly). Example for "user@example.com" with password "secret":

Authorization: Basic dXNlckBleGFtcGxlLmNvbTpzZWNyZXQ=

So, in Ruby, you can create such headers like so:

Base64.strict_encode64("#{username}:#{password}")

Note that when speaking to a REST API, you should be using libraries like RestClient or HTTParty which will wrap ...

In ruby you can easily read and write CSVs with the standard CSV library class.

On top of this, you can use the gem smarter_csv for reading (not writing) CSVs in a more comfortable way:

• Keep in mind, that the development of this gem is in an unknown state and the 2.0 release seems to happen never
• The API will change completely for 2.0, so you might find a bunch of unrelated documentation for 1.2

Here is an example...

To restart all tasks monitored by God, don't use god restart. This command is only meant to soft-restart a given process or group.

Instead you should:

god stop
god terminate
god start -c yourgodconfig.god