My presentation on "Hello WordPress" for the Mauritius Software Craftsmanship Community on 22 February 2014. Download the files at: https://github.com/rrikesh/hello-wordpress-mscc and read my blog post : http://blog.rrikesh.com/wordpress/hello-wordpress-introduction-wordpress/

1. Hello WordPress
By Rikesh Ramlochund
@rrikesh

2. What is WordPress?

3. What is WordPress?
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WordPress is a CMS
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Almost 11 years old!
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Open Source – GPL v2 or later
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People mostly use WordPress as a blogging platform
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Powers the wordpress.com blog network

4. What is WordPress?
Usage not limited to blogs
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Corporate websites
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Web Apps
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Multisite
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Forum
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Ecommerce

5. Why WordPress?
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Smooth learning curve.
Elegant admin interface (called the WordPress
Dashboard)
Dashboard has a responsive layout
Lots of people use it, help is easily available through
various communities.
The WordPress Codex is concise

6. Why WordPress?
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As a developer, lots of job prospects
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As a client, easy to use dashboard
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Backwards compatible
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Upgrades to newer versions run smoothly
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Most used CMS, by far. (source: w3techs)

7. WordPress on the WWW
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Where to look for help?
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WordPress.org Forum
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Stack Overflow
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WordPress Answers (The WordPress branch of the
Stackexchange network)
/r/wordpress subreddit

8. WordPress for Bloggers
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Wordpress.com v/s self hosted
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Limitations of customisation wordpress.com
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A self hosted blog is easy to set up!

9. WordPress Installation
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Download WordPress
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wget http://wordpress.org/latest.zip
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Create a database
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Rename wp-config-sample.php to wp-config.php
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Add database configurations to wp-config.php
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OPTIONALLY add other configuration settings
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Open your website url in a browser and follow the steps.

10. Wp-config.php
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WordPress configuration file
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Allows us to:
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Define debugging mode
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Add salts
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Change language
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Change table prefix
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Define post revisions and autosave frequency
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And more!

11. Security
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Never install WordPress which you didn't download from
WordPress.org
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Always update your CMS, plugins and themes regularly
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File Permissions:
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find /path/to/your/wordpress/install/ -type d -exec
chmod 755 {} ; (directories)
find /path/to/your/wordpress/install/ -type f -exec
chmod 644 {} ; (files)

12. Security
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Some people add a layer of protection by implementing
BasicAuth on their wp-admin folder
A second layer of protection can be added where scripts
are generally not intended to be accessed by any user.
(wp-includes folder)
Securing wp-config.php to a directory above the WP
install
Disable File Editing
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define('DISALLOW_FILE_EDIT', true);

13. Security
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Backups are handy if something goes wrong
There are plugins available that check if your installation
is secure
On the Codex:
http://codex.wordpress.org/Hardening_WordPress.html

14. Permalinks
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Allows us to define pretty links in WordPress
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Available in Settings → Permalinks
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Uses .htaccess to perform the rewrite
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More SEO friendly links
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From http://localhost/mscc/?p=123 to
http://localhost/mscc/sample-post/

15. WordPress Development
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Here’s the fun part.
WARNING: Don’t modify the WordPress core, plugins
and themes since they will get updated
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Modify the default behaviour of WordPress using hooks
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WordPress has two types of hooks:
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Action
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Filter

16. WordPress Development
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About WordPress actions
An action is a PHP function that is executed at specific
points throughout the WordPress Core.
For example, send a mail to the admin each time a new
post is created.

17. WordPress Development
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About WordPress filters
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Filters usually modifies data before displaying.
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Filters are not intended to modify contents of the
database.
For example, if you want to change all words in your post
to upper case, you can use a filter to do so before
displaying.

18. WordPress Themes
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Themes reside in the wp-content/themes folder
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Commercial themes can be updated, but you’ll lose your changes.
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Use Child Themes if you’re not using a custom built theme (i.e. a
theme that will get updated)
Choose from more than 2,200 free themes http://wordpress.org/themes/
Never use pirated versions of paid themes. Piracy is bad (and
malware will pwn you!)
Themes are not only used for templating needs, but can also
contain functions to customise the behaviour of WordPress

19. WordPress Plugins
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Plugins also extend WordPress functionalities
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They are located in the wp-content/plugins folder
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Commercial plugins can be updated, don’t modify them,
you’ll lose your changes.
Choose from more than 29,500 free plugins –
https://wordpress.org/plugins/
Never use pirated versions of paid plugins. Piracy is bad
(and malware will pwn you!)

20. Theme or plugin?
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Since both can be used to add functionalities, when to use
what?
Use a plugin if you want to keep your behaviour even
after changing themes. Eg. Google Analytics
Note that theme and plugin functions can also be
wrapped in a class!

21. Plugins development
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Same thing as in functions.php
You can copy/paste functions from functions.php to a
plugin and vice versa
Plugins have three additional hooks:
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activation hook
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deactivation hook
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uninstall hook
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Read more:
http://wordpress.stackexchange.com/q/25910/17305

22. Theme Structure
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The bare minimum a theme can have is an index.php and
a style.css file
Theme information is stored in the style.css file
WordPress uses its Template Hierarchy to decide which
template to render for a given page
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Pages can have specific templates to choose from
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The last fallback is index.php

23. Child Theme
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Easily extend a parent theme.
Sometimes you build your theme around a framework,
like Genesis, Roots or Underscores. Frameworks get
updated too!
Read more: http://codex.wordpress.org/Child_Themes
You should make your themes compatible with child
themes, if you want to distribute them.

24. Child Theme
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The Template in the style.css refers to the directory name
of the parent
The child theme can overwrite any file present in the
parent theme. Use another file with the same name.
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Child theme's functions.php does not get overwritten.
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It gets loaded together with the parents functions.php
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However, child's theme functions.php gets loaded first!
You can overwrite functions defined in the parent's theme
if they are encapsulated with function_exists();

25. Custom Post types and fields
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WordPress can be extended to create more post types,
taxonomies and custom fields
Custom post types and Taxonomies are easily created
programmatically
I recommend using a plugin like Advanced Custom
Fields for creating custom fields in your posts

26. Options API
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The Options API allows us to save variables in the
Database – in the options table
The most used functions available are get_option(),
update_option(), and delete_option()
For example, if you want to save some theme or plugin
settings.
Arrays are automatically serialised before storing

27. Dashboard menu pages
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You can add your own settings pages in the WordPress
dashboard.
You can use add_menu_page() and add_submenu_page()
You can also hook on to existing pages, by using
add_theme_page(), add_plugins_page(),
add_users_page(), add_management_page(),
add_options_page(), etc...

28. Shortcode API
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Some kind of filter used in the WYSIWYG
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A [shortcode] is evaluated to some string
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Shortcodes can take parameters. For example
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[gallery id=”123” size=”medium”]
[ads type=”smallbox”]
Can be used in templates using do_shortcode()

29. Theme Customizer API
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Recently added API
The WP Customizer API allows theme developers to
provide a live theme modification preview.
For example: change heading colour, site name, site
description.

30. WP_Query
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WP_Query is a class that allows you to craft detailed
requests to query your content.
You may want the four latest posts from a category from
a particular author
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WP_Query parameters are passed as an array
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$result = new WP_Query( $args );
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Use wp_reset_postdata() when using multiple loops on a
page

31. Ajax
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WordPress has its own way of dealing with ajax.
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Add a parameter called action to your ajax data
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Hook to wp_ajax_nopriv_{action} for users not logged in
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Hook to wp_ajax_{action} for users logged in
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add_action('wp_ajax_ajaxdemo', 'callback');

32. The End
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Questions?
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If you have questions after this presentation:
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Tweet me: @rrikesh
Mail me: contact@rrikesh.com
Learn more on http://codex.wordpress.org