Drupal 8: Most common beginner mistakes

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Drupal 8: Most Common
Beginner Mistakes
@iztokIztok Smolic

Iztok Smolic
iztok@agiledrop.com
Follow me: @iztok
AGILEDROP Ltd.
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A smart man makes a mistake,
learns from it, and never makes
that mistake again. But a wise
man finds a smart man and
learns from him how to avoid
the mistake altogether.
Roy H. Williams
“

DRUPAL 7 PRESENTATION
You can find the
Drupal 7 version
here:
http://goo.gl/bHG9v2

YOUR FIRST MISTAKE WILL BE TO THINK
THAT YOU WILL DO (TOO) MANY MISTAKES
I am happy to say that it was very hard to find
20 mistakes specifically for Drupal 8.

“FROM NOW ON WE WILL BE DOING ALL
PROJECTS WITH DRUPAL 8”
Is Drupal 8 ready?
Take the time to conduct research of release
plan and progress on key modules.
There is a lot less modules that support specific
business logic, e.g. commerce.

Module research

NOT USING DRUPAL 8 SOON ENOUGH
Drupal 7 is a comfort zone. Whenever you are in
the comfort zone it means you are not growing.
Consider using Drupal 8 as investment. If that
doesn’t work, try to remember how it felt when
you had to support Drupal 6 site when Drupal 7
was out.

http://buytaert.net/how-is-drupal-8-doing

LOOKING FOR MODULE THAT IS ALREADY IN
DRUPAL 8 CORE
After installing Drupal 8, you can actually setup a
useful website.
A list of modules and their state in Drupal 8:
http://www.bluespark.com/status-top-100-
contributed-modules-drupal-8

NEW FOLDER STRUCTURE
Where should I place modules and themes in
Drupal 8?
Drupal 8 has a new folder structure and once
again you don’t know where to place
downloaded modules.

• /core - All files provided by core, that doesn't have an explicit
reason to be in the / directory. More details futher down.
• /libraries - 3rd party libraries, eg. a wysiwyg editor.
• /modules - The directory into which all modules go.
• /profiles - contributed and custom profiles.
• /themes - contributed and custom themes
• sites/[domain OR default]/{modules,themes} - Site specific
modules and themes.
• sites/[domain OR default]/files - Site specific files. This could
be files uploaded by users, such as images.
• /vendor - Backend libraries that Drupal Core depends on.
(Symfony, Twig, etc)

YOU DON’T KNOW HOW TO START
LEARNING ABOUT DRUPAL 8
• Where can I find tutorials for Drupal 8 custom
development?
• I can’t find any documentation for Drupal 8!
Start with official documentation:
https://api.drupal.org/api/drupal/core
%21core.api.php/group/extending/8.2.x

Official documentation is behind, but
commercial training providers are catching up.
DrupalizeMe tutorials 
https://drupalize.me/guide/learn-drupal-8
Drupal 8 books: 
https://www.drupal.org/books?availability%5B
%5D=38414&version%5B%5D=20236

GET FAMILIAR WITH OOP
You need a good knowledge of OOP otherwise you
may stack in the first alter. It is the time to get
started with OOP if you haven't already.
https://buildamodule.com/collection/drupal-8-
developer-prep
https://www.drupal.org/getting-started-d8-bkg-
prereq

NOT USING PHP IDE
You need a PHP IDE (eg PHPStorm) by default.
Having OOP, PSR, Services etc make an IDE a
requirement even for a front end developer.
You cannot continue with an Editor.

REVISE SERVER REQUIREMENTS, LOCAL
DEVELOPMENT AND PRODUCTION
• Dedicated even more resources than you did
for Drupal 7 (memory_limit in particular).
• Upgrade your PHP!
• Everyone on your team should have exactly the
same development environment.

NOT KNOWING HOW TO DEBUG DRUPAL 8
Something in your code doesn’t work as expected,
but you can’t figure out what.
Module Devel is still a must have: 
https://www.drupal.org/project/devel
Debug Drupal 8 with PHPstorm:
http://redcrackle.com/blog/drupal-8/phpstorm

YOU DIDN’T PROPERLY DISABLED CACHE
You refresh the page … and nothing. Your
beautifully written code does not run.
If you don’t want to clear cache for every page
refresh follow the instructions to disable
Drupal 8 caching during development:
https://www.drupal.org/node/2598914

MANAGING CONFIGURATION ON
PRODUCTION
You made a quick fix on production and forgot to
export it to Git repo. On the next deployment the config
and maybe even the content are gone - for good.
Config readonly module:  
https://www.drupal.org/project/config_readonly
Use files only configuration storage:  
https://www.drupal.org/node/2416555

YOU MISS ALL OFF THOSE DIVS AND
CLASSES THAT WE HAD IN DRUPAL 7
Some hate it, some love it - I am talking about
divitis and classitis. This is now gone from Drupal 8
by default.
If you want your theme to include Drupal's
classes on your elements, define Classy as your
base theme.
https://www.drupal.org/theme-guide/8/classy

BUT I NEED TO USE PHP IN THE TEMPLATES
It has never been so obvious why we have
preprocess functions. Because it’s limiting, you
can do so much now.

HOW TO FIND TEMPLATES? HOW TO LIST
ALL VARIABLES INSIDE A TEMPLATE?
First, enable development mode: https://www.drupal.org/
node/2598914.
Use Devel (https://www.drupal.org/project/devel) and Search
Kint (https://www.drupal.org/project/search_kint) to render
variables inside templates.

There is also now a Google Chrome plugin called
Drupal Template Helper which moves all your
Twig debug output to a Chrome web inspector
tab.

JQUERY LIBRARIES ARE NOT LOADED
jQuery or any other library is not loaded on
every page by default.
Enable it by  
defining it as a 
dependency.

HAVING TOO MUCH HOPES IN QUICK EDIT
Quick Edit is a great feature on paper. In reality it brings
additional technical debt.
When using Quick Edit consider:
• Are all fields visible?
• Can all fields work in a front-end widget?
• How not to override Quick Edit CSS/JS?
Remember Drupal’s 7 Overlay? First module to disable.

DRUPAL 8 IS THE BEST THING SINCE SLICED
BREAD
>

Drupal 8: Most common beginner mistakes

Drupal 8: Most common beginner mistakes

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