One of the main reasons for WordPress being so successful is how extendable it is, and it has a huge percentage of the web running on it. Developers can use plugins to attach nearly any functionality to a WordPress site without changing the WordPress software. In fact, if you have a specific need that doesn’t have an existing plugin or you want to create something that will be of benefit to the WordPress community and learning how to do it is a very useful and rewarding skill.
This tutorial teaches you the fundamentals and process of creating your first WordPress plugin. It might be useful to have some experience with PHP programming to follow the concepts explained here, but not necessary.
Understanding What a Plugin Actually Is
WordPress Plugins are a collection of PHP functions that are downloaded into WordPress to add to or alter WordPress’ capabilities. WordPress uses a system of hooks to let external code interact with WordPress at certain points in its operation.
Plugins can be found within directories under the wp-content/plugins directory of a WordPress installation. All plugins are stand-alone and can be turned on and off from the WordPress admin panel.
Learning to understand this architecture is the first and foremost step in learning how to create WordPress plugins.
Setting Up Your Development Environment
To develop and test your plugin without impacting an existing website, you’ll need to have a WordPress development environment in your local area.
There are some local development tools that enable you to run WordPress on your own computer such as LocalWP, MAMP, WAMP or Laragon. The LocalWP is easy to use and install, as it automates PHP and database installation on the server with minimal configuration, making it ideal for beginners.
Your local WordPress environment is up and running and you can install and test your plugin with all error logs and debugging capabilities without any concerns.
Creating Your First Plugin File
Once you’ve got a WordPress installation, the first thing to do when creating a WordPress plugin is to make a new folder within the wp-content/plugins directory. Give your folder a name that is different and contains information about your plugin.
Create a PHP file in this folder with the same name as the folder. At the top of this file add a plugin header comment block. This is a block of specially formatted comments that tells WordPress the name of your plugin, its description version number and the author information. WordPress retrieves this data and uses it to show the admin dashboard your plugin.
The minimum plugin header will contain the Plugin Name field. Otherwise WordPress won’t recognize the file as a valid plugin.
Understanding Hooks: Actions and Filters
The basis of WordPress plugins working with WordPress are its hooks. There are two types of hooks: actions and filters.
Action hooks let your plugin run some code at certain times during WordPress’ processing. There are several examples of how it could be used: for instance, if you activate the init action after WordPress has loaded but before anything is sent to the browser. The wp_enqueue_scripts action is used to properly add CSS and JavaScript files to a page.
Filter hooks are used to alter data before WordPress uses it, with the help of your plugin. For example the the_content filter lets your plugin modify the content of posts before they are displayed. The Title Tag filter allows you to edit the title tag.
The add_action and add_filter functions are used to attach your code to hooks. These two functions and how to use them are the most critical technical skills to master while developing WordPress plugins.
Writing Your First Plugin Function
You have a plugin file written and some understanding of hooks and can now write the code for your first functional plugin.
A basic example would be a plugin which appends a message to the bottom of each post. You would have written a PHP function which receives the content of the post as an input and makes an addition to it and returns it. If so, you would use add_filter to add this function to the the_content filter.
WordPress calls the the_content filter when it displays a post. Your function replaces the content with the added message, and then returns it to WordPress, which then shows it for you.
This is a basic example which illustrates the principal used in pretty much every function of a WordPress plugin.
Working With the WordPress Database
A lot of plugins require to store or retrieve data and WordPress offers a neat way to do it via the global wpdb object. There are methods for safely running database queries, such as protecting against SQL injection with support for prepared statements, in the wpdb class.
WordPress also includes a simple “option” API for storing simple settings information. Instead of using the database directly, the get_option and update_option functions can be used to store and retrieve configuration values. This is the easiest way to save plugin settings.
Plugins are often used to create custom database tables when they are first activated with the register_activation_hook function, for more complicated data structures.
Creating Admin Settings Pages
Over time, every plugin will require some sort of settings page in the WordPress admin area. WordPress has a built-in settings API which is used to render and sanitize settings forms.
Settings page are added via add_menu_page or add_submenu_page, and hooked into via the admin_menu action. It is simply a WordPress settings API page that takes care of a lot of the complexity in building these pages, such as nonce verification and sanitizing data.
A well-organized and clean settings page can help make your plugin much more usable, particularly if you plan to share it with other WordPress users.
Final Thought
Creating WordPress plugins is an immense opportunity to extend and customize WordPress websites. Begin with a simple plugin that performs one thing very well. Learn about the action and filter hook system. Then add more advanced features as you become more comfortable with the code. WordPress developer documentation is great and there’s a large and supportive community. All great plugins out there today began with the same basic structure you are utilizing in building yours.
FAQs
Do I need to know PHP to develop WordPress plugins?
Basic PHP knowledge is required since WordPress is built on PHP. You do not need to be an expert but understanding variables functions arrays and basic object-oriented concepts will allow you to write functional plugins.
How do I make my plugin available to other WordPress users?
You can submit your plugin to the WordPress.org plugin directory for free distribution. Plugins must meet WordPress coding standards and pass a review process before being published.
What is the difference between a plugin and a theme in WordPress?
Themes control the visual presentation of a WordPress site. Plugins add or modify functionality. A plugin should work regardless of which theme is active and a theme should work regardless of which plugins are installed.
How do I debug my WordPress plugin?
Enable WordPress debugging by setting WP_DEBUG to true in the wp-config.php file. This displays PHP errors and warnings that are hidden by default. The Query Monitor plugin provides additional debugging information about database queries and hooks.
Are there security considerations specific to WordPress plugin development?
Yes. Input sanitization output escaping and nonce verification are the three most important security practices. Always sanitize data coming in validate it before using it and escape data before outputting it to the browser.
