According to W3Techs, WordPress powers 43.1% of all websites. This is because WordPress has a ton of built-in functionalities, but also because it is highly customizable through plugins. Plugins are a critical component of the WordPress platform, allowing you to easily extend functionality that goes beyond the WordPress core without modifying it.
For example, WooCommerce converts your WordPress site into an eCommerce store, enabling you to sell products and services to your clients through the web. Yoast SEO is a plugin that helps you manage your SEO to rank your posts higher on search engines.
While developers can list their plugins on the web for anyone to use, these plugins may not solve your specific requirements. There are almost sixty thousand plugins in the official WordPress plugin directory, which means you should check if an existing plugin matches your requirements before building your own. If there isn’t one that matches your needs, you should consider creating a custom WordPress plugin.
In the background, scripting, and query languages like PHP and SQL power WordPress. Therefore, expertise in these technologies, as well as experience with deployment, are necessary to create a WordPress plugin.
In this tutorial, we will guide you through the creation of your first plugin.
How Do I Learn WordPress Plugin Development?
Learning WordPress plugin development is a valuable skill, especially if you aim to manage the costs of plugin development by handling it yourself. Here’s a streamlined guide to help you build a strong foundation in this area, regardless of your current experience level with WordPress.
Essential Skills and Knowledge
To start developing WordPress plugins, you need familiarity with:
- PHP: the main server-side language in WordPress.
- SQL (Structured Query Language): allows you to directly interact with the database, perform queries, and manage WordPress site data via Creating, Reading, Updating, and Deleting (CRUD) data operations.
- HTML, CSS, and JavaScript: basic elements for crafting web pages and interfaces. HTML (HyperText Markup Language) structures the web page, CSS (Cascading Style Sheets) is used for styling, and JavaScript adds interactivity.
- WordPress ecosystem: including themes, plugins, and hooks.
Educational Resources and Community Engagement
- Online tutorials and courses: platforms like Udemy, LinkedIn Learning, and WPBeginner offer structured learning paths covering basics to advanced plugin development techniques.
- WordPress Plugin Handbook: this official plugin handbook provides detailed information on creating plugins, including coding standards and examples, and is regularly updated.
- Frameworks and tools: Explore WordPress MVC for an organized, MVC-based approach to development and WPPB Boilerplate for a structured start in line with WordPress coding standards.
- Forums and meetups: join the WordPress Stack Exchange, local Meetups, and WordCamps to engage with other developers, share knowledge, and stay informed on the latest trends.
Practical Application
- Develop your own plugins: begin by addressing specific needs or problems with your plugins. Each project enhances your understanding and confidence in development.
- Feedback and peer review: seek constructive criticism from experienced developers and study the code of others to learn different approaches and techniques.
Basic Concepts of WordPress Plugin Development
When WordPress gets updated to a new version, it overrides its core files. Because of this, if you add custom functionality to a WordPress site by directly modifying the WordPress core, your changes will be wiped out upon WordPress upgrade. This leads to one of the core WordPress development concepts – any functionality you want to add or modify should be done using plugins.
A WordPress plugin is essentially one or more functions defined in PHP files, as PHP is the main scripting language powering WordPress. It also typically has 3 other components: hooks (action hooks and filter hooks), shortcodes, and widgets. These are the main elements of WordPress plugin development.
Hooks
Hooks are features in WordPress that allow you to manipulate a process at a specific point without changing WordPress core files. Therefore, hooks provide a way for your plugin to attach to the working WordPress core. You can associate code snippets or functions with hooks to execute at various points in time.
There are two types of hooks:
An action hook allows you to trigger your own custom functions at specific points in the WordPress execution flow. For instance, when a post is published, an action hook can trigger a function that executes a particular task, like sending a notification email.
To work with an action hook, use the add_action() function. The basic syntax of this function is add_action( 'hook_name', 'your_function_name' ), where hook_name is the name of the action hook provided by WordPress, and your_function_name is the name of the function you want to execute.
A filter is used to modify or manipulate data before it is used by WordPress or sent to the database. Unlike action hooks, which trigger actions at specific points, filter hooks are designed to alter text, content, or other data, giving developers the ability to change default WordPress behavior or data.
Similar to action hooks, you attach your custom functions to a filter hook. However, the key difference is that your function should return a modified version of the data it receives.
To work with a filter hook, use the add_filter() function like so:
add_filter( 'filter_hook_name', 'your_custom_function_name' );
For example, add_filter( 'the_content', 'your_custom_function_name' ) would apply your function to the content of posts and pages.
The function you hook to a filter should accept at least one parameter (the data to be filtered) and should return the modified data. Here’s a simple structure:
function your_custom_function_name( $content ) {
// Modify $content here
return $content;
}
The most common filter hooks are:
the_content: Filters the post content.the_title: Filters the post title.wp_title: Filters the title in the head section.the_excerpt: Filters the post excerpt.
Incorporating Plugin APIs
In addition to hooks, WordPress provides various Plugin APIs that offer extended functionalities for development. These APIs enable you to interact with different aspects of WordPress – for example:
- Settings API (for creating settings pages in the admin area).
- REST API (for interacting with WordPress data using HTTP requests).
- Shortcode API (for creating shortcodes).
- Customizer API (for adding options to the WordPress customizer).
By leveraging these APIs, developers can create more complex and integrated functionalities within their plugins, enhancing both efficiency and capability.
Combining the use of hooks and Plugin APIs forms a comprehensive approach to WordPress plugin development, allowing for powerful customizations and integrations without the need to modify WordPress core files. For instance, you might use an API to add a new feature and then use hooks and filters to alter its behavior or output.
Shortcodes
When you develop a plugin, it does not directly have access to the WordPress theme. To communicate with the WordPress theme and display some information to the user, you need to use a shortcode. Shortcodes allow users to insert a dynamic HTML element into a post or a page.
Here is an example of a shortcode that adds the text “Hello World” to your post:
//Register shortcode
Widgets
Widgets provide developers with another way to display your plugin’s content to the end user. WordPress has a WP_widget class in PHP that you need to extend to create a widget for your plugin.
Now that we covered the basic concepts of WordPress plugin development, let’s explore the key steps in creating a custom plugin.
Blocks
With the introduction of the Gutenberg editor in WordPress, blocks have become a crucial aspect of plugin development. Each piece of content, whether it’s a paragraph, image, button, or custom element, is treated as an individual “block”.
By making custom blocks, developers can create plugins that integrate with the Gutenberg editor seamlessly. Developers have the freedom to design these blocks in a way that matches their functionality. They can include various options and settings within the block, allowing users to customize them as needed.
For example, a custom block for displaying testimonials might include options for text alignment, background color, and the addition of an image.
Building custom blocks often involves using modern web development technologies like React and JavaScript along with PHP. .
How to Develop a WordPress Plugin: Step-by-Step
Step 1 – Define the Requirements
The first step in WordPress plugin development is to clearly define your development needs. Before you start, ensure that you have a clear idea of the objective of the plugin. When you have an accurate picture of the issue to resolve, you are able to execute your idea into an efficient plugin.
There are many factors that you can consider in this step. What are the features of this plugin? How are you going to update or customize your plugin? What will the design look like?
Make sure to answer these questions because this step is linked to all the other steps of the process.
In this specific example, we are going to create a Hello World plugin. We will use this simple, bare-bones plugin as an example to illustrate the steps that you should follow to create a WordPress plugin.
Step 2 – Develop the plugin
First, ensure you have a working WordPress environment. You can set this up locally on your computer using tools like MAMP, WAMP, XAMPP, or Local by Flywheel.
- Navigate to your WordPress installation directory.
- Go to the wp-content/plugins directory, which is the default plugins directory for WordPress.
- Create a new folder for your plugin, e.g., hello-world.
Creating the hello-world plugin folder.
- Inside your hello-world folder, create a new PHP file. The file name should ideally match your plugin folder, e.g., hello-world.php.
- Open the file in a text editor or IDE such as Visual Studio Code (VS Code).
- At the top of your hello-world.php file, add the following plugin header information to tell WordPress the name, description, version, and author of the plugin (You can find the contents of a sample file header in the WordPress codex):
<?php |
- The plugin handbook of WordPress should serve as a guide for this step. This is the step where you bring your idea to life. For this tutorial we are going to start by writing a simple PHP function to output “Hello World”:
function show_hello_world() { |
- Now, we can this function to wp_footer to display the message in the footer of your site, for example:
add_action('wp_footer', 'show_hello_world'); |
Step 3 – Activate the plugin on WordPress
The default WP directory for storing plugin code in the back end is /wp-content/plugins/. How you structure your plugin within this directory will depend on the complexity of the plugin. The name of the directory is the same as your plugin name, in lowercase and dashes in place of spaces.
We recommend having a single PHP file that contains all the code of the plugin (/wp-content/plugins/my-plugin/my-plugin.php). Such a structure is ideal for a simple plugin that serves a small function.
If you plan to work with a plugin that has a lot of assets, you can organize your plugin based on the function of the code and PHP files. You can create directories such as assets for CSS and JavaScript files, i18n for localization files, templates, and widgets.
For more complex plugins, you can create an MVC view with directories for model, view, and controller within the my-plugin directory. This helps in debugging later in a shorter time. In our simple and straightforward example of the Hello World plugin, we will create the hello-world directory with a single PHP file, hello-world.php, inside it.
A developer often works on a WordPress plugin in a development environment. To shift the plugin to your production site, you would need to compress the plugin directory and upload the zipped plugin file to WordPress Admin.
For this tutorial, in our local environment, we’re going to:
- Open the WordPress admin dashboard and navigate to Plugins.
- You’ll find the Hello World plugin we just created. Click on Activate.
Activating the Hello World plugin we just created.
- After activating, visit your WordPress site and scroll down to the footer. You should see “Hello World!” displayed.
Best Practices for Plugin Development in WordPress
You can quickly get into WordPress plugin development by using the right tools. A text editor that you are comfortable with, an FTP client to quickly shift files between your local machine and the server, and a development server to test your plugin on the server help you in creating your plugin through quick iterations.
Creating a plugin from scratch requires a lot of time and effort. While there is no standard process for creating a plugin, you can opt for plugin development through a boilerplate. Using a boilerplate saves a lot of time by reusing code.
While developing a plugin, use the inbuilt-functions features of WordPress whenever possible to avoid rework and shorten web development time. Adhere to WordPress coding standards while developing your plugin.
Use MVC structure to ensure a consistent structure for others to add to your plugin conveniently at a later stage.
Update your plugin to ensure compliance with the latest versions of PHP and WordPress. This keeps your website safe from security risks.
Bonus tips from Codeable plugin development experts
Expert WordPress plugin developers Bishoy A and Joseph Gabito advise:
Always sanitize and escape data
When writing a plugin, it’s very important to secure the output of your plugin by using the appropriate WordPress data sanitization functions. Failing to do so puts your plugin and your whole website at risk of hacking. Let’s take the following PHP statement as an example:
echo $my_custom_variable
Written this way, it allows intruders to put some custom JavaScript or MySQL code to it, which can then lead to XSS and/or MySQL injection attacks. That’s why you want to use the built-in security function esc_html and instead write:
echo esc_html( $my_custom_variable )
esc_html() function, just like its name suggests, escapes all HTML and JavaScript codes in your variable, making it more secure. There are a lot of similarly used functions; refer to the WordPress Codex for documentation about all functions.
Use WPDB whenever possible
When you start writing a plugin that does custom CRUD operations (Create, Read, Update, Delete) in the database, it is strongly advised to use the WordPress database abstraction class called wpdb.
There are a lot of advantages to using WPDB. One of the most important benefits is security. Instead of writing your methods to secure your queries, wpdb already provides built-in security methods to protect your queries from database hacks such as $wpdb->prepare.
Additionally, $wpdb class can potentially save you a lot of time.
Always consider internationalization (i11n) and make your plugin easily translatable
Internationalization is the process of developing your plugin in a way that it can easily be translated into other languages. For example, a “Save” button coded like this wouldn’t support i11n.
<button id=”exampleButton”>Save</button>
Instead, it has to be coded like this to ensure it is translatable:
<button id=”exampleButton”><?php _e( ‘Save’, ‘text_domain’ ); ?></button>
To ensure you’re doing i11n right. You can also follow the official WordPress Internationalization documentation.
Prefix functions and add a namespace to Class
When writing a plugin for the first time, you may be tempted to write a function like the following:
function get_data() {
While this might work for you when working on your local development environment, the chances of naming collision with other plugins will be very high since there might be some plugins installed in your wp site using the same function name, thus producing a PHP Fatal Error.
To solve this problem, developers are advised to prefix their functions. For example, instead of writing get_data (), you’ll change the name of the function from get_data() to your_prefix_get_data().
Change your_prefix to match the directory name of your plugin or text-domain. In our example, we’ll use hello_world _get_data().
Additionally, you may want to make sure there are no existing functions that calls on the same function name, so you can do something like:
if ( ! function_exists(“hello_world_get_data”) ) {
This method not only prevents a naming collision but also makes your function overwritable via Theme or Child Theme.
Final Thoughts on WordPress Plugin Development
In this tutorial on WordPress plugin development, we explored how you can create a plugin from scratch. While it requires technical expertise and patience, you can achieve your goal of launching a plugin with the relevant knowledge, skills, best practices, and the willingness to get your hands dirty. However, if you don’t have any foundational skills and limited time to learn the basics yourself, you can consider working with a professional WordPress developer specializing in custom plugin development.
Plugin development and customization are some of the most popular services that our vetted experts offer on Codeable.
Frequently Asked Questions
How to learn WordPress plugin development?
There are thousands of great tutorials and video courses online, but we would recommend going through and familiarizing yourself with the official WordPress documentation first.
The official Plugin Development Handbook
What are the benefits of WordPress plugins?
Plugins enhance the functionality of your WordPress site. We create plugins to ensure that we do not change WordPress core, which is overwritten with every WordPress update.
What is the difference between WordPress and WooCommerce plugin development?
WordPress plugin development focuses on enhancing the overall functionality of a WordPress site, covering a wide range of features such as SEO, security, and content management. In contrast, WooCommerce plugin development is specific to e-commerce functionalities on WordPress sites. These plugins are tailored to improve online store aspects like payment gateways, product listings, shopping carts, and customer management. While both require similar foundational skills in WordPress development, WooCommerce plugins demand a more specialized understanding of e-commerce dynamics and needs.
Do I need to create a new plugin for my website?
It depends. There are already thousands of existing plugins that you should check out. If you don’t find the right plugin for you, consider creating one that suits your needs.
Where are WordPress plugins stored?
Any WordPress plugin that you download and install on your site is stored in the directory /wp-content/plugins/. Consequently, any plugin that you create should also be stored in the same directory.
What skills do I need to start with WordPress plugin development?
To create a WordPress plugin, you should have a solid understanding of the core technologies that power WordPress: HTML/CSS, JavaScript for the front end, and PHP, SQL for the back end.
How do I publish my plugin to the WordPress plugin directory?
If your plugin adheres to the requirements and guidelines for a WordPress plugin, you can publish it on the WordPress plugin directory through these simple steps.
How can I uninstall my plugin?
The easiest way to permanently remove a plugin is to deactivate and delete it from your WordPress admin dashboard, then delete its directory. Additionally, you can explore the uninstall hook to automate the uninstallation process.
I do not have the skills to develop a plugin? How should I proceed?
If you are new to WordPress plugin development with limited coding experience, you should try and get your hands dirty with a small-scope plugin. However, if you need a more complex plugin, you may consider working with an experienced developer through Codeable.
