Phoenix:
WordPress is the most accepted blogging and CMS platform out there at present.
Part of what has made it so booming is its capability to be extended via
plugins to execute any function you wish for. Developing a plugin framework is
really hard, but WordPress has one of the best solutions seen till date. So how
do you get on with taking benefit of it and building your own plugin?
WordPress
development is done in PHP, which make it quite accessible as developers
usually know their way the language. Building a plugin is just a matter of
making a basic file structure and employing WordPress provided functions and
even hooks to
WordPress
development is done in PHP, which make it pretty accessible as developers
generally know their way around the language. Building a plugin is just a
matter of creating a basic file structure and using WordPress provided
functions and event hooks to actuate your application.
The File
Structure
All it takes to building a plugin is a single PHP file, but general practice
says that you house your plugin and its files within a directory. To start,
create a directory to hold your plugin and give it a name corresponding your
plugin. Then, in that directory, create your main PHP file, again naming the
file with the name of your plugin:
+ super-plugin
- super-plugin.php
If your plugin is going to involve any images, javascript, css, or
additional PHP files, you will house those within this directory as well:
+ super-plugin
+ admin
- super-plugin-admin.php
+ img
- icon.png
+ js
- super-plugin.js
- super-plugin.php
- readme.txt
In this case, I’ve created 3 directories, admin, img, and js to hold my
extra files. The super-plugin-admin.php file will be employed to offer a web
interface to your plugin on the WP backend.
Lastly, if you plan on hosting your plugin in the WordPress plugin
directory, you will need to take in a file named readme.txt at the root of the
directory. The file must follow the set-up detailed in this readme.txt example.
Defining Your Plugin
Subsequently, we have to define our plugin so that WP will recognize it and
let it to be installed, removed, and activated.
Open your main plugin file, super-plugin.php and add the following to the
top of the file:
<?php
/*
Plugin Name: Name Of The Plugin
Plugin URI: http://URI_Of_Page_Describing_Plugin_and_Updates
Description: A brief description of the Plugin.
Version: The Plugin's Version Number, e.g.: 1.0
Author: Name Of The Plugin Author
Author URI: http://URI_Of_The_Plugin_Author
License: A "Slug" license name e.g. GPL2
*/
?>
Replace each line with the data for your plugin. This will label your plugin
details for WordPress. At a minimum you need the Plugin Name: field for the
plugin to be known.
Initializing your program
Now that WordPress identifies your plugin, it’s time to make it do
something. This is achieved by employing predefined WordPress functions and
hooks. A hook is an event listener that is trigger based on outside events
happening. If your program required performing any type of setup, such as
database table creation, you can tap into the plugin activation hook like so:
//SETUP
function super_plugin_install(){
//Do some installation work
}
register_activation_hook(__FILE__,'super_plugin_install');
Then, when a user activates your plugin, any function that has been
registered with the activation hook will be executed.
You might also want to register some custom javascript that your plugin will
need to work. You can do this by using the add_action hook to piggyback on to
another process. In this case, we’re going to listen for the wp_enqueue_scripts
event to trigger and let WordPress know that we want in on the script party and
to please execute our function as well.
//SCRIPTS
function super_plugin_scripts(){
wp_register_script('super_plugin_script',plugin_dir_url(
__FILE__ ).'js/super-plugin.js');
wp_enqueue_script('super_plugin_script');
}
add_action('wp_enqueue_scripts','super_plugin_scripts');
When scripts are being loaded up, your function will get carried out and
your script will get registered and queued to be added into the head portion of
the HTML.
Finally, you want to in fact run your program. You can do this by listening
to various WP hooks and waiting for an apt event that would trigger your code
to run. If you want to run your program each time a visitor comes to your site,
you can use the ‘init’ or ‘wp_loaded’ action to trigger your code:
//HOOKS
add_action('init','super_plugin_init');
/********************************************************/
/* FUNCTIONS
********************************************************/
function super_plugin_init(){
//do work
run_sub_process();
}
function run_sub_process(){
//more work
}
In this instance, the super_plugin_init() function will get called on every
new request and you can perform whatever logic you need. If your plugin is
complex, you can add extra PHP files to put up out your application and just
use this initial hook to trigger the full application. A full list of the
actions that run during a usual request can be found here.
Conclusion
With these elements ready, you’re off and running with your own WordPress
plugin. What you do with it is up to you, but you’re only restricted by your
imagination. Uploading your directory to your WordPress installation will make
your plugin appear in the plugins section and you can turn on it like any other
plugin.
Next up, you’ll probably want some way to administer the plugin on the
backend of WordPress. In my next post, I’ll show you how to get started with
that process.
Read more:
WordPress Plugin Development
