Download - An easy guide to Plugin Development
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Plugin DevelopmentWordPress Meet-up!on 2014/05/29!in Bangkok, Thailand!by Shinichi Nishikawa
about Me❖ ผมชอชน (Shinichi Nishikawa)!
❖ อยทกรงเทพฯปครงLived in Bangkok for half a year!
❖ สราง themes และ plugin ใหลกคา Building themes and plugins for customers!
❖ ผมชอบเขยนบลอก เขยนหนงสอเกยวกบ WordPress และจด WordPress Events ทญปนดวย.I write blogs with WP, I write books of WP, I ran WP events
Challenge
❖ ผมจะสอนวธทำpluginอยางงายI will try to explain how to make plugins as easy as possible.!
❖ หากคณมคำถาม คณถามไดทกเวลา Don’t hesitate to ask questions any time!!
❖ คณสามารถดาวนโหลด presentation และ codesนไดPresentation and codes online will be uploaded.
Menu❖ plugin ขนพนฐาน
Plugin basic!
❖ WordPress ทำงานอยางไร How WordPress works!
❖ plugin ทำงานกบ WordPress อยางไร How plugins work together with WordPress!
❖ ผมมตวอยางpluginงายๆ3แบบ ทจะทำใหคณเขาใจYou will see 3 example plugins and understand them
After session
❖ คณสามารถจะทำpluginอยางงายไดYou can make a simple plugin!
❖ คณจะรวาpluginทำหนาทอะไร You will know what plugins do!
❖ คณจะชอบWordPressมากขน You will be more interested in WordPress core
Enquete
❖ ใครทำWordPress ThemeไดบางAnyone who can make WP Theme?!
❖ ใครทำPluginไดบางAnyone who can make WP Plugin?!
❖ ใครรจกphpบางWho knows php?
plugin คอ อะไรWhat is a plugin?
What is a plugin?
❖ Tool to extend WordPress functionality!
❖ Without changing Core codes!
❖ Over 30,000 plugins at WordPress.org/plugins/
ตองมอะไรบาง What do we need?
What do we need?
a WordPress
Get a clean install of a WordPress.
What do we need?
php, html, css, js
Plugins are written in php.!!Many plugins have html & css.!!Some plugins have Javascript.
php / basics
❖ variables!
✓ $a!
✓ $hubba!
✓ $posts
❖ functions!
function my_func() { do_something(); }
❖ others!
✓ if!
✓ foreach!
✓ array
php / template tags
❖ the_title()!
❖ the_permalink()!
❖ the_date()!
❖ the_content()
❖ wp_title()!
❖ body_class()!
❖ get_post_thumbnail_id()!
❖ wp_nav_menu()
basic
wp-content/plugins/easy-plugin.php
WPจะรวานเปนplugin. WP knows it’s a plugin.
This comment is called plugin header.
wp-admin/plugins.php
WP shows the plugin “Plugin Name: ” comes here.
More Plugin Header<?php!/*!Plugin Name: Plugin งาย มาก!!Plugin URI: http://nskw-style.com/my-plugin!Description: plugin แรกของผม!Version: 0.1!Author: Shinichi Nishikawa!Author URI: http://nskw-style.com!License: GPLv2 or later!Text Domain: easiest!*/
wp-admin/plugins.php
WP shows the plugin Those are required if you want your plugin to be in wordpress.org site.
ตวอยาง Examples
ผมทำตวอยาง plugin 3 แบบ!I made 3 plugins for tonight.
คณจะเขาใจใน 30 นาท!!
It may seem difficult but!you’ll understand in 30 minutes.
1 ใจเยนๆ
<?php!/*!Plugin Name: ใจเยนๆ!Description: Tell people to take it easy.!*/
1 ใจเยนๆ
2 สภาพ
<?php!/*!Plugin Name: สภาพ!Description: This plugin make all content polite.!*/
2 สภาพ
3 สบายใจ login
<?php!/*!Plugin Name: สบายใจ login!Description: This plugin make login screen happy.!*/
3 สบายใจ login
Plugins have codes like,!!
add_action( ‘location’, ‘function’ );!or!
add_filter( ‘location’, ‘function’ );!
Let’s see how 3 plugins work.
I will explain the concept of plugin!and!
we come back to these examples.
Concept of Plugin
We need to know how!WordPress works.
WordPress Process
WordPress Process
WordPress process
WordPress Processrequest: example.com/category/food
User sees the page.
WordPress process
WordPress Processrequest: example.com/category/food
User sees the page.Get DB info from wp-config.php
connect to DB
WordPress Processrequest: example.com/category/food
User sees the page.Get DB info from wp-config.php
connect to DB
load core functions
load plugins
load functions.php
WordPress Processrequest: example.com/category/food
User sees the page.Get DB info from wp-config.php
connect to DB
load core functions
load plugins
load functions.php
query from URL
get post(s) data from DB
WordPress Processrequest: example.com/category/food
User sees the page.Get DB info from wp-config.php
connect to DB
load core functions
load plugins
load functions.php
template file decided. (category.php)
query from URL
get post(s) data from DB
category.php! header.php loop sidebar.php footer.php
WordPress Processrequest: example.com/category/food
User sees the page.
WordPress process
WordPress Processrequest: example.com/wp-admin/post-new.php
User sees the page.
WordPress process
WordPress Processes can be … !
✓ displaying home page ✓ displaying admin page ✓ displaying login page ✓ or any other things WordPress does
WordPress Processrequest: example.com/wp-login.php
User sees the page.
WordPress process
WordPress Processes can be … !
✓ displaying home page ✓ displaying admin page ✓ displaying login page ✓ or any other things WordPress does
That’s how WordPress works.
Now, the question is!!
“how can plugins work!with the process of WordPress?”
I need to talk about “Hooks”,!the Secret Key of WordPress.
Hooks
WordPress process
Hooks
WordPress process
Hooks?
❖ Plugins access to hooks to put extra functions to WordPress!
❖ There are 2 types of hooks.!
✓ Filter Hooks!
✓ Action Hooks
Hooks
Filter Hooks
WordPress process
Action Hooks
Actions!&!
Filters
action
❖ Action is to do something.!
✓ to echo something!
✓ to save something!
✓ to redirect somewhere
filter
❖ Filter is to change something!
✓ change original text to your text!
✓ change original html to your html!
✓ change original php values to your values.
How hooks look like
apply_filters( ‘location1’, $value );
do_action( ‘location2’ );
filter hook
action hook
How hooks look like
❖ apply_filters( ‘location_name’, $value );!
❖ do_action( ‘location_name’ );
case: in Templates
apply_filters( ‘the_content’, $value );
do_action( ‘wp_footer’ );
ex ) example.com/about
filter hook
action hook
case: login screen
apply_filters( ‘login_message’, $value );
do_action( ‘login_footer’ );
ex ) example.com/wp-login.php
filter hook
action hook
case: admin pages
apply_filters( ‘admin_body_class’, $value );
do_action( ‘admin_head’ );
ex ) example.com/wp-admin/
filter hook
action hook
There are many hooks
name1 name2 name3 name5 name6 name7name4
there are 1,000+ filter hooks & 500+ action hooks
in WordPress
How to hook
How to registerapply_filters( ‘location1’, $value ); do_action( ‘location2’ );
Hooking Filters & Actions
❖ add_filter( ‘location’, ‘your_func_name’ );!
❖ add_action( ‘location’, ‘your_func_name’ );
Hooking Filters & Actions
❖ add_filter( ‘location’, ‘your_func_name’ ); function your_func_name( $default ) { // do something return $new; }
Hooking Filters & Actions
❖ add_action( ‘location’, ‘your_func_name’ ); function your_func_name(){ // do something }
Register filter
add_filter( ‘location1’, ‘func1’ ); function func1($value){ // make a filter here return $value }
apply_filters( ‘location1’, $value ); do_action( ‘location2’ );
Register action
add_action( ‘location2’, ‘func2’ ); function func2(){ // do something }
apply_filters( ‘location1’, $value ); do_action( ‘location2’ );
Plugin Hook Concept
add_filter( ‘location1’, ‘func1’ ); function func1($value){ // make a filter here return $value }
add_action( ‘location2’, ‘func2’ ); function func2(){ // do something }
apply_filters( ‘location1’, $value ); do_action( ‘location2’ );
Plugin Hook Concept
Plugin is a set of add_action() & add_filter()
add_filter( ‘location1’, ‘func1’ ); function func1($value){ // make a filter here return $value }
add_action( ‘location2’, ‘func2’ ); function func2(){ // do something }
apply_filters( ‘location1’, $value ); do_action( ‘location2’ );
Plugin Hook Concept
Large plugins have many functions in them.
apply_filters( ‘location1’, $value ); do_action( ‘location2’ );
we go back to example plugins
ใจเยนๆ
ใจเยนๆrequest: example.com/category/food
User sees the page.Get DB info from wp-config.php
connect to DB
load core functions
load plugins
load functions.php
template file decided. (category.php)
query from URL
get post(s) data from DB
category.php! header.php loop sidebar.php footer.php
wp_head();
wp_footer();
สภาพ
สภาพ
สภาพrequest: example.com/category/food
User sees the page.Get DB info from wp-config.php
connect to DB
load core functions
load plugins
load functions.php
template file decided. (category.php)
query from URL
get post(s) data from DB
category.php! header.php loop sidebar.php footer.php
apply_filters( ‘the_content’, $content );
สภาพ
a little advanced
This is also possible.
สบายใจ login
สบายใจ login
สบายใจ loginrequest: example.com/wp-login.php
User sees the page.
check cookies
see ssl condition
check errors
show logo & message<html>
</head>show <form>
do_action(‘login_footer’); !in plugin: echo <video>
display login footer
do_action(‘login_head’); !in plugin: echo <style>
สบายใจ login
More things you can do with plugins.
add favicon to admin pages
change excerpt “[…]”
Hide admin notice of upgrades
shortcode
Resources
Resources
❖ Codex!
✓ http://codex.wordpress.org/Writing_a_Plugin!
✓ http://codex.wordpress.org/Plugin_API!
✓ http://codex.wordpress.org/Plugin_Resources!
❖ wordpress.org!
✓ http://developer.wordpress.org/reference/
Next meet-up!!
“How to build theme properly”!and!
“How to sell it on WordPress.com”
แนะนำหวขอทนาสนใจไดนะครบ!Any suggestions for coming meet-up?
