View

JavaScript without jQuery (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 only on a desktop computer.

Have you benchm...

Trigram indexing as an alternative to PostgreSQL fulltext search

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...

Linked content

How to drop all tables in PostgreSQL

To remove all tables from a database (but keep the database itself), you have two options.

Option 1: Drop the entire schema

You will need to re-create the schema and its permissions. This is usually good enough for development machines only.

DROP SCHEMA public CASCADE;
CREATE SCHEMA public;

GRANT ALL ON SCHEMA public TO postgres;
GRANT ALL ON SCHEMA public TO public;

Applications usually use the "public" schema. You may encounter other schema names when working with a (legacy) application's database.

Note that f...

Repeats

Merging two arbitrary ActiveRecord scopes

Rails 3+ allows you to join two scopes from arbitrary sources by calling the merge method:

scope1 = User.where(:email => 'foo@bar.com')
scope2 = User.where(:first_name => 'hans')
merged_scope = scope1.merge(scope2)

merged_scope.to_a will now trigger a query for the combined scope chain:

SELECT `users`.* FROM `users` WHERE `users`.`email` = 'foo@bar.com' AND `users`.`first_name` = 'hans'

If you are joining two models, you can also [merge scopes for different models](http://blog.thefrontiergroup.com.au/2011/03/composing...

Deprecated

How to overwrite and reset constants within Cucumber features

In order to save the original value of a constant, set the new value and restore the old value after a scenario was completed, you can use the following helper. It takes care of saving the old constant value, setting the new one without throwing warnings and resets the value with an After hook.

This module also enables you to introduce new global constants.
Since these newly defined constants do not have any value to be reset to,
they simply are deleted (remove_const) once the respective Cucumber step finishes.

You can copy the file at...

Upgrading Ruby from 1.8.7 to 2.3.5

Suggested Workflow

Set the ruby version in .ruby-version to 2.3.5, then perform these steps one by one, fixing errors as they occur:

  1. Update gems as listed below, and bundle
  2. Boot a Rails console - see below for a list of changes you will probably need
  3. Run Specs with --backtrace option
  4. Run Cucumber features (with Geordi's --debug option)
  5. When all tests are green, look through your Gemfile and remove as many version constraints as possible.
  6. Boot the application in different environements to spot further issues, e...
Repeats

What collapsing margins are, how they work and when margins do not collapse

What collapsing margins are

Imagine you have 2 HTML boxes. The first one has a margin-bottom of let's say 30px and the second one a margin-top of 20px. After rules of collapsing margins have been applied we have a margin of 30px (not 50px) between these two boxes (see this article for an illustration) . This is because no addition of both margins takes place but the maximu...

Linked contentRepeats

Geordi hints

Reminder of what you can do with Geordi.

Note: If you alias Geordi to something short like g, running commands gets much faster!
Note: You only need to type the first letters of a command to run it, e.g. geordi dep will run the deploy command.

geordi deploy

Guided deployment, including push, merge, switch branches. Does nothing without confirmation.

geordi capistrano

Run something for all Capistrano environments, e.g. geordi cap deploy

geordi setup -t -d staging

When you just c...

Repeats

Copying validation errors from one attribute to another

When using virtual attributes, the attached trait can be useful to automatically copy errors from one attribute to another.

Here is a typical use case where Paperclip creates a virtual attribute :attachment, but there are validations on both :attachment and :attachment_file_name. If the form has a file picker on :attachment, you would like to highlight it with errors from any attribute:

class Note < ActiveRecord::Base
  has_attached_file :attachment
  validates_attachment_presenc...
Repeats

Cucumber Factory: How to assign polymorphic associations

Cucumber factory supports polymorphic associations out of the box. Just keep in mind that you need to use named associations for this purpose.

class Person < ApplicationModel
  has_many :buildings, inverse_of: :owner
end

class Company < ApplicationModel
  has_many :buildings, inverse_of: :owner
end

class Building < ApplicationModel
  belongs_to :owner, optional: true, polymorphic: true
end

Works

Given there is a person with the name "Nice person"
  And there is a buildin...
Linked contentRepeats

The Easiest Way to Parse URLs with JavaScript

A very clever hack to parse a structured URL object is to create a <a> element and set its href to the URL you want to parse.

You can then query the <a> element for its components like schema, hostname, port, pathname, query, hash:

var parser = document.createElement('a');
parser.href = 'http://heise.de/bar';
parser.hostname; // => 'heise.de'
pathname = parser.pathname; // => '/bar'

if (pathname[0] != '/')
  pathname = '/' + pathname // Fix IE11

One advantag...

How to upgrade Rails: Workflow advice

When upgrading Rails versions -- especially major versions -- you will run into a lot of unique issues, depending on the exact version, and depending on your app.

However, it is still possible to give some generic advice on how you want to tackle the update in principle.

How many update steps?

Besides the Rails upgrade itself, you might also want to

  • upgrade your other gems
  • upgrade your Ruby versions

First decide in how many steps you want to run the upgrade. I suggest

  • To do a separate step for each major rails versions. So, if...
Repeats

How to combine "change", "up", and "down" in a Rails migration

Rails migrations allow you to use a change method whose calls are automatically inverted for the down path. However, if you need to some path-specific logic (like SQL UPDATE statements) you can not define up and down methods at the same time.

If you were to define define all 3 of them, Rails would only run change and ignore up and down. However, Rails 4+ features a helper method called reversible:

class MyMigration < ActiveRecord::Migration

  def...
Repeats

Javascript: Don't throw exceptions from async functions

TLDR: A function is hard to use when it sometimes returns a promise and sometimes throws an exception. When writing an async function, prefer to signal failure by returning a rejected promise.

The full story

When your function returns a promise ("async function"), try not throw synchronous exceptions when encountering fatal errors.

So avoid this:

function foo(x) {
  if (!x) {
    throw "No x given"
  } else
    return new Promise(function...

ActiveJob Inline can break the autoloading in development

We figured out, that ActiveJob Inline might lead to autoloading problems in development. The result was an exception when running an import script, which delivers async mails.

A copy of XXX has been removed from the module tree but is still active! (ArgumentError)

Our fix was to use .deliver_now and not .deliver_later (this is not a general fix, but it was okey for us). Below there are some debug hints which helped us to locate the problem:

  • We placed a pry debugger in [ActiveSupport#clear](https://github.com/rails/rails/blob...
Repeats

Regular tasks for long-running projects

When projects run for many years, they require special regular maintenance to stay fresh. This kind of maintenance is usually not necessary for small or quick projects, but required to keep long-running projects from getting stale.

You should be able to fit this into a regular development block.

Quarterly

Check which libraries need updating

As time goes by, libraries outdate. Check your software components and decide if any of it needs an update. Your main components (e.g. Ruby, Rails, Angular) should always be reasonably up to ...

Repeats

Building web applications: Beyond the happy path

When building a web application, one is tempted to claim it "done" too early. Make sure you check this list.

Different screen sizes and browsers

Desktops, tablets and mobile devices have all different screen resolutions. Does your design work on each of them?

  • Choose which browsers to support. Make sure the page looks OK, is usable and working in these browsers.
  • Use @media queries to build a responsive design
    • If you do not suppo...
Repeats

Don't forget: Automatically remove join records on has_many :through associations

Bad

# Given the following models

class Image < ActiveRecord::Base
  has_many :album_image
  has_many :albums, through: :album_images
end

class Album < ActiveRecord::Base
  has_many :album_image
  has_many :images, through: :album_images
end

# Join model
class AlbumImage < ActiveRecord::Base
  belongs_to :album
  belongs_to :image
end

Destroying a record in this setup will only remove the record itself, and leave orphaned join records behind.

image = Image.last
image.destroy # removes only the `image` record,
             ...
This website uses cookies to improve usability and analyze traffic.
Accept or learn more