This document provides an overview of plugin development practices for WordPress. It discusses prerequisites for plugin development including understanding PHP and having a goal in mind. It covers common WordPress terminology, structuring a plugin with directories, adding the main plugin file, using object-oriented or procedural programming, interacting with the WordPress core, working with databases, adding CSS and JavaScript, creating admin menus, using permissions, implementing shortcodes, ensuring quality, and launching the plugin. The document aims to guide developers through best practices for building WordPress plugins.

1. PLUGIN DEVELOPMENT
PRACTICES
Presented By: Dan Pastori
@danpastori 521 Dimensions
TECHNOLGY SOLVING NEEDS

2. Dan Pastori

3. WHO AM I?
Primary PHP/Java Developer
Co-Founded 521 Dimensions
Been tearing apart Wordpress for 3 years
Built two large plugins and one theme

4. PRODUCTS I’VE DEVELOPED FOR
And of course custom applications!

5. WORDPRESS IS THE BEST!
(at least from my experience!)
Great Documentation
Great Community
Fast learning curve

6. PRE-REQUISITES
Understanding of PHP
Motivation/Consistency
A goal to develop towards

7. BEGIN THE JOURNEY

8. COMMON WP TERMINOLOGY
Hooks (there are 2 types):
1. A Filter - Modifies text before it hits the screen.
2. An Action - Hooks launched during execution.

9. WHAT SHOULD I BUILD?
1. Find a need
2. Focus on the need
3. Prototype
4. Jump right in and start building!

10. STRUCTURE YOUR PLUGIN
Create Directories
/wp-content/plugins/[NAME]
/wp-content/plugins/[NAME]/css
/wp-content/plugins/[NAME]/js
/wp-content/plugins/[NAME]/images
Depending on Coding Style
/wp-content/plugins/[NAME]/classes
/wp-content/plugins/[NAME]/includes

11. ADD MAIN FILE
/wp-content/plugins/[NAME]/[NAME].php
* File must be named the name of your plugin

12. Now for some excitement!
Add Header in Main File
/*
Plugin Name: [NAME]
Plugin URI: http://www.521dimensions.com/wp-pictures
Description: Pictures in Wordpress!
Version: 1.0
Author: Dan Pastori
Author URI: http://www.521dimensions.com
License: GPL2
*/

14. OOP VS PROCEDURAL?
Modern programming practices say OOP
Both work!
I recommend OOP if you are familiar

15. BEGIN CODING!
DO NOT OVER-WRITE CORE FUNCTIONALITY
Interacting with the Core:
Predefined Functions
Actions
Filters
(They’re there for a reason!)

16. What happens when you activate and
deactivate?
Procedural
register_activation_hook(__FILE__, ‘function_name’)
register_deactivation_hook(__FILE__, ‘function_name’)
OOP
register_activation_hook(__FILE__, array($this, 'product_list_install'));
register_deactivation_hook(__FILE__, array($this, 'product_list_deactivate'));

17. Open [NAME].php
OOP
...
class WPPictures {
static function install() {
// do not generate any output here
}
}
register_activation_hook( __FILE__, array('WPPictures', 'install') );
Procedural
...
function wp_pictures_install(){
}
register_activation_hook( __FILE__, ‘wp_pictures_install’ );

18. __FILE__
(IT’S MAGIC!)
It’s a pre-defined constant in PHP
The full path and filename of the file. If used inside an include,
the name of the included file is returned.
http://php.net/manual/en/language.constants.predefined.php

19. WORKING WITH THE DATABASE
global $wpdb object
$wpdb->query($query)
$wpdb->get_results($query)
$wpdb->print_error($query)
dbDelta()

20. INITIAL INSTALL
In your install() function
1. Check for upgrades
If {installed version} != {plugin version}
2. Create Tables
3. Set options

21. CSS AND JS
Register first, enqueue second
wp_register_script('product_js', plugins_url('/js/product_list.js',
__FILE__));
wp_enqueue_script('thickbox',null,array('jquery'));

22. ADMIN MENUS
add_menu_page(PAGE TITLE, MENU TITLE, PERMISSION, SLUG, FUNCTION, LOGO);
add_submenu_page(PARENT SLUG, PAGE TITLE, MENU TITLE, 'CAPABILITY', 'MENU SLUG', 'FUNCTION');

23. DASHBOARD VISUAL APPEAL
One management page, append to settings menu
Multiple management pages, have it’s own heading

24. PERMISSIONS
Prevents unwanted access
current_user_can('manage_options')
http://codex.wordpress.org/Roles_and_Capabilities

25. SHORTCODES
Dramatically increases user-experience of your plugin
Allows for custom control of display of data
add_shortcode('product-list', 'product_list_shortcode');
extract( shortcode_atts( array(
'categoryID' => 'all',
), $attributes ));
[product-list category-id = 1]

26. ENSURE PLUGIN QUALITY
Not only be accepting, but invite criticism
DOCUMENT... PLEASE :)
Update
Don’t solve everything, do one thing right

27. BE THE SERVER ADMIN’S FRIEND
(And have a quality plugin)
Minimize requests
Make sure your resources are present
Use common php packages
Don’t require 777 on ANY directory!

28. LAUNCH PLUGIN
Have your Mom use your plugin
Accept criticism
Maintain thorough documentation
Website maybe?

29. QUESTIONS?
@