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Linked contentRepeats

Using pure Sass functions to make reusable logic more useful - Advanced

Functions and mixins are very similar in nature. Because they can both accept variables, you might end up creating a mixin when what you really need is a function.

Repeats

Browsers will not send a referrer when linking from HTTPS to HTTP

  • When your site is on HTTPS and you are linking or redirecting to a HTTP site, the browser will not send a referrer.
  • This means the target site will see your traffic as "direct traffic", i.e. they cannot distinguish such hits from a user who directly typed in the URL.

Reasons for this behavior

It's probably because of this RFC:

Clients SHOULD NOT include a Referer header field in a (non-secure) HTTP request if the referring page was transferr…

Git: Apply a diff

git apply allows you to apply a diff onto your HEAD. Most often you can achieve the same result with a rebase & merge.

Example:

master                commit1 - commit3
feature-branch                \ commit2 - commit4
git checkout feature-branch
git reset --hard commit3
git diff ..commit4 | git apply
master                commit1 - commit3
feature-branch                          \ Unstaged commit 2 & 4

You can also [create a patch and apply it afterwards](https://makandracards.com/makandra/2521-git-how-to…

Repeats

Capybara: Quick checking for element presence (without retries or timeout)

Element finding is a central feature of Capybara. Since #find is normally used to get elements from the current page and interact with them, it's a good thing that some Capybara drivers (e.g. Selenium) will wait an amount of time until the expected element shows up. But if Capybara cannot #find it at all, you'll get an error.

if page.find('.that-element')
  # Do something
else
  # Never happens because #find raises
end

In order to simply check whether an element is present, without errors raised, you can use #has_css?. It wil…

Repeats

Jasmine: using async/await to write nice asynchronous specs

Jasmine has long standing support for writing asynchronous specs. In days gone by we used the done callback to achieve this, but these days it is possible to write much more readable specs.

Async specs

As a first example, say we want to check that some form disables the submit button while working.

```js
// bad (how we used to do it)

beforeEach(() => {
this.form = setupMyForm()
this.submitButton = findTheSubmitButton()
})

it('disables the submit button while working', (done) => {
expect(this.submitButton.disabled).toBe(false) …

Adding Jasmine JavaScript specs to a Webpack(er) project

The goal is to get Jasmine specs running in a Rails project using Webpacker, with the browser based test runner. Should be easily adaptable to a pure Webpack setup.

Image

Step 1: Install Jasmine

yarn add jasmine-core

Step 2: Add two separate packs

Since we do not want to mix Jasmine into our regular Javascript, we will create two additional packs. The first only contains Jasmine and the test runner. The second will contain our normal application code and the specs themselves.

We cannot…

Repeats

How to make RubyMine aware of Cucumber steps defined in gems

If your Ruby project includes a gem like Spreewald that comes with some external step definition, RubyMine does not know about them by default and will highlight the step as an undefined reference:

Image

To link these external step definitions to RubyMine, add the corresponding gems to your RubyMine-Settings:

  • Go to Settings (ctrl + alt + s)
  • Go to Languages and Frameworks
  • Go to Cucumber
  • There, add your gem (e.g "spreewald") via the little "+" from the b…

How to get a backtrace if rspec (or any other ruby process) hangs with no output

If rspec hangs with no output and you dont get a backtrace neither with --backtrace nor by just killing it with crtl-c,
you can put the following in your spec/spec_helper.rb:

```ruby
puts "rspec pid: #{Process.pid}"

trap 'USR1' do
threads = Thread.list

puts
puts "=" * 80
puts "Received USR1 signal; printing all #{threads.count} thread backtraces."

threads.each do |thr|
description = thr == Thread.main ? "Main thread" : thr.inspect
puts
puts "#{description} backtrace: "
puts thr.backtrace.join("\n")
end

Linked contentRepeats

How to send HTTP requests using cURL

  • Reading a URL via GET:

    curl http://example.com/
    
  • Defining any HTTP method (like POST or PUT):

    curl http://example.com/users/1 -XPUT
    
  • Sending data with a request:

    curl http://example.com/users -d"first_name=Bruce&last_name=Wayne"
    

    If you use -d and do not set an HTTP request method it automatically defaults to POST.

  • Performing basic authentication:

    curl http://user:password@example.com/users/1
    
  • All together now:

    curl http://user:password@example.com/users/1 -XPUT -d"screen_name=batman"
    

Repeats

Cucumber: Clear localStorage after each scenario

Capybara clears cookies before each scenario, but not other client-side data stores. If your app is using localStorage or sessionStorage, contents will bleed into the next scenario.

Use this hook to remove all site data after each scenario:

After do
  if Capybara.current_driver == :selenium && !Capybara.current_url.starts_with?('data:')
    page.execute_script <<-JAVASCRIPT
      localStorage.clear();
      sessionStorage.clear();
    JAVASCRIPT
  end
end
Repeats

How to define constants with traits

This is pretty much like defining subclasses through traits with the Modularity gem.

module MyConstantTrait
  as_trait do
    
    self::MY_CONSTANT = 'hello universe'
    
  end
end

This would set MY_CONSTANT for any class using the trait.

Of course you can also use parameters (for logic or for setting values, like here):

module DoesValues
  as_trait do |*args|
    
    self::VALUES = args
    
  end
end

class Foo
  include D...
Repeats

ActiveType 1.2 supports "change_association"

With ActiveType 1.2 you can modify associations (has_many etc.) after they have been defined.

One common use case for this is to change an association inside a form model, like this:

class Credential < ActiveRecord::Base
end

class User < ActiveRecord::Base
  has_many :credentials
end

class SignUpCredential < ActiveType::Record[Credential]
end

class SignUp < ActiveType::Record[User]
  change_association :credentials, class_name: 'SignUpCredential'
end

Now, if you load credentials, y…

Unpoly: Testing values for presence or blankness

In Ruby on Rails, all objects have a useful blank? method. It returns true for nil but also for empty strings or empty arrays. There is also a universal method present? which returns true for all values that are not blank?.

In JavaScript you need to roll your own implementation of blank? and present?.

If your application uses [Unpoly](…

How to: Fix json 1.8.3 with Ruby 2.5

The gem json fails to install for Ruby 2.5 if you use a version equal or below 1.8.3.

Run bundle update json --conservative to solve this issue.

The backtrace you will encounter looks like this:

```
Building native extensions. This could take a while…
ERROR: Error installing json:
ERROR: Failed to build gem native extension.

current directory: /home/user/.rbenv/versions/2.5.3/lib/ruby/gems/2.5.0/gems/json-1.8.3/ext/json/ext/generator /home/user/.rbenv/versions/2.5.3/bin/ruby -I /home/user/.rbenv/versions/2.5.3/lib/ruby/si...
Linked content

Katapult EOL

Katapult was an endeavor to dramatically speed up starting a new Rails application. However, it turned out to save less time than expected, while requiring more time for maintenance than anticipated. Since its benefits fell too low, we have decided to not continue developing Katapult.

You can still use Katapult for generating ready-to-run applications with model CRUD, authentication and all of Katapult's features, but the rapid development of the web will quickly render the generated code antiquated. Nevertheless, its architecture may remai…

Linked contentDeprecated

faviconit.com: Super-simple favicon generator

Eduardo Russo was tired of complex favicon creation and created his own favicon generator. It's really easy and allows a lot of image editing before rendering the favicons, in all needed sizes, formats and with the HTML needed to include them!

In Rails applications with Haml:

  • put all the favicon files into /public
  • store the HTML to app/views/layouts/_favicon.html
  • add = render 'layouts/favicon' to <head> in your application layout(s)

… and you're all…

LoDash: isBlank and isPresent mixins

When you need to check a value for presence, don't rely on JavaScript since it considers 0 or "0" false. Also don't rely on LoDash's _.isEmpty:

if ('0') { ... } // false
if (0) { ... } // false
if (!_.isEmpty('0')) { ... } // true (= good)
if (!_.isEmpty(0)) { ... } // false (= not good)

This is because isEmpty it is only meant for objects with a length.

While the name implies that it's meant only for collections, you probably still want something like isBlank or `is…

Linked content

Active Record and PostgreSQL — Ruby on Rails Guides

Rails guide that covers PostgreSQL-specific column types and usages for Active Record.

You should especially keep in mind the special datatypes that PostgreSQL offers. \
Types like json and array take away a lot of the pain that you had on MySQL projects.

Example use cases for array are tags or storing foreign keys (instead of a join model). You can even index them.

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