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Developing a WordPress plugin using Claude 3.5 Sonnet.

In this guide, I’ll walk you through the process of developing your own WordPress plugin from scratch, with the added benefit of AI assistance at each stage.

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WordPress is one of the most popular content management systems in the world, powering over 40% of all websites. One of the reasons for its popularity is its extensibility through plugins. In this guide, I’ll walk you through the process of developing your own WordPress plugin from scratch, with the added benefit of AI assistance at each stage.

Table of Contents

  1. Understanding WordPress Plugins
  2. Setting Up Your Development Environment
  3. Creating the Basic Plugin Structure
  4. Writing the Main Plugin File
  5. Adding Functionality to Your Plugin
  6. Creating Admin Pages
  7. Working with WordPress Hooks
  8. Handling Database Operations
  9. Implementing Shortcodes
  10. Adding Widget Support
  11. Internationalization and Localization
  12. Security Considerations
  13. Testing Your Plugin
  14. Preparing for Distribution
  15. Submitting to the WordPress Plugin Directory

1. Understanding WordPress Plugins

WordPress plugins are PHP scripts that extend or modify WordPress functionality. They can:

  • Add new features to WordPress
  • Modify existing functionality
  • Integrate WordPress with external services
  • Alter the admin interface
  • Enhance the user experience on the front-end

Plugins work by hooking into WordPress’s event-driven architecture, allowing developers to execute custom code at specific points during the WordPress execution process.

AI Assistance: To get started with conceptualizing your plugin, you might ask an AI:

“I want to create a WordPress plugin that [describe functionality]. Can you help me outline the main features and components I should consider?”

2. Setting Up Your Development Environment

Before you start coding, you need a proper development environment:

  1. Install a local server environment like XAMPP, MAMP, or Local by Flywheel.
  2. Install WordPress on your local server.
  3. Set up a code editor (e.g., Visual Studio Code, Sublime Text, or PhpStorm).
  4. Install Git for version control (optional but recommended).

AI Assistance: If you’re unsure about the setup process, you can ask:

“What are the essential tools and software I need to set up a local development environment for WordPress plugin development? Please provide a step-by-step guide.”

3. Creating the Basic Plugin Structure

Every WordPress plugin needs a specific file structure:

my-plugin/
├── my-plugin.php
├── readme.txt
├── languages/
├── includes/
├── admin/
└── public/

AI Assistance: To get help with setting up your plugin structure, you might ask:

“Can you show me the basic file structure for a WordPress plugin named [plugin name], including the main plugin file and its contents?”

4. Writing the Main Plugin File

The main plugin file (my-plugin.php) should start with a plugin header comment:

<?php
/**
 * Plugin Name: My Awesome Plugin
 * Plugin URI: https://example.com/plugins/my-awesome-plugin/
 * Description: This plugin does something awesome.
 * Version: 1.0.0
 * Author: Your Name
 * Author URI: https://example.com/
 * License: GPL-2.0+
 * License URI: http://www.gnu.org/licenses/gpl-2.0.txt
 * Text Domain: my-awesome-plugin
 * Domain Path: /languages
 */

// If this file is called directly, abort.
if (!defined('WPINC')) {
    die;
}

// Define plugin constants
define('MY_AWESOME_PLUGIN_VERSION', '1.0.0');
define('MY_AWESOME_PLUGIN_PATH', plugin_dir_path(__FILE__));
define('MY_AWESOME_PLUGIN_URL', plugin_dir_url(__FILE__));

// Include dependencies
require_once MY_AWESOME_PLUGIN_PATH . 'includes/class-my-awesome-plugin.php';

// Begin execution of the plugin
function run_my_awesome_plugin() {
    $plugin = new My_Awesome_Plugin();
    $plugin->run();
}
run_my_awesome_plugin();

5. Adding Functionality to Your Plugin

Now that you have the basic structure, you can start adding functionality. Here’s an example of a simple function that adds a custom footer message:

function my_awesome_footer_message() {
    echo '<p>This site is powered by My Awesome Plugin!</p>';
}
add_action('wp_footer', 'my_awesome_footer_message');

AI Assistance: When you’re ready to add specific functionality, you can ask:

“I need to add a feature to my WordPress plugin that [describe specific functionality, e.g., ‘adds a custom widget’]. Can you provide the necessary code and explain how it works?”

6. Creating Admin Pages

To add settings or configuration options, you’ll need to create admin pages:

function my_awesome_plugin_menu() {
    add_options_page(
        'My Awesome Plugin Settings',
        'My Awesome Plugin',
        'manage_options',
        'my-awesome-plugin',
        'my_awesome_plugin_options_page'
    );
}
add_action('admin_menu', 'my_awesome_plugin_menu');

function my_awesome_plugin_options_page() {
    // Check user capabilities
    if (!current_user_can('manage_options')) {
        return;
    }
    ?>
    <div class="wrap">
        <h1><?= esc_html(get_admin_page_title()); ?></h1>
        <form action="options.php" method="post">
            <?php
            // Output security fields for the registered setting "my_awesome_plugin_options"
            settings_fields('my_awesome_plugin_options');
            // Output setting sections and their fields
            do_settings_sections('my-awesome-plugin');
            // Output save settings button
            submit_button('Save Settings');
            ?>
        </form>
    </div>
    <?php
}

AI Assistance: For help with creating admin pages, you might ask:

“Can you provide the code to create a settings page for my WordPress plugin in the admin area? Include form fields for [list desired settings].”

7. Working with WordPress Hooks

WordPress hooks are the foundation of plugin development. There are two types of hooks:

  1. Actions: Allow you to add or modify WordPress functionality.
  2. Filters: Allow you to modify data during the execution of WordPress core, plugins, and themes.

Example of using an action hook:

function my_awesome_init_function() {
    // Do something when WordPress initializes
}
add_action('init', 'my_awesome_init_function');

Example of using a filter hook:

function my_awesome_title_filter($title) {
    return 'Awesome: ' . $title;
}
add_filter('the_title', 'my_awesome_title_filter');

AI Assistance: To learn more about using hooks, you can ask:

“How can I use WordPress action hooks to [describe desired action, e.g., ‘add a custom admin menu’]? Please provide a code example and explanation.”

8. Handling Database Operations

If your plugin needs to store data, you can use the WordPress database API:

global $wpdb;

// Insert data
$wpdb->insert(
    $wpdb->prefix . 'my_awesome_table',
    array(
        'column1' => 'value1',
        'column2' => 'value2',
    )
);

// Retrieve data
$results = $wpdb->get_results("SELECT * FROM {$wpdb->prefix}my_awesome_table");

AI Assistance: For help with database operations, you might ask:

“I need to create a custom database table for my WordPress plugin. Can you show me how to create the table on plugin activation and provide examples of inserting and retrieving data?”

9. Implementing Shortcodes

Shortcodes allow users to easily add plugin functionality to their posts and pages:

function my_awesome_shortcode($atts = [], $content = null) {
    // Normalize attribute keys, lowercase
    $atts = array_change_key_case((array)$atts, CASE_LOWER);

    // Override default attributes with user attributes
    $atts = shortcode_atts([
        'title' => 'My Awesome Title',
    ], $atts);

    // Start output buffering
    ob_start();
    ?>
    <div class="my-awesome-shortcode">
        <h2><?php echo esc_html($atts['title']); ?></h2>
        <?php echo wp_kses_post($content); ?>
    </div>
    <?php
    // End output buffering and return the buffer contents
    return ob_get_clean();
}
add_shortcode('my_awesome', 'my_awesome_shortcode');

Users can then use the shortcode like this: [my_awesome title="Custom Title"]Content here[/my_awesome]

AI Assistance: To get help with implementing shortcodes, you can ask:

“I want to create a shortcode that [describe shortcode functionality]. Can you show me how to implement this in my WordPress plugin?”

10. Adding Widget Support

To create a widget, you need to extend the WP_Widget class:

class My_Awesome_Widget extends WP_Widget {
    public function __construct() {
        parent::__construct(
            'my_awesome_widget', // Base ID
            'My Awesome Widget', // Name
            array('description' => 'A widget that does awesome things.') // Args
        );
    }

    public function widget($args, $instance) {
        // Output the widget content
    }

    public function form($instance) {
        // Output the widget options form
    }

    public function update($new_instance, $old_instance) {
        // Process widget options to be saved
    }
}

function register_my_awesome_widget() {
    register_widget('My_Awesome_Widget');
}
add_action('widgets_init', 'register_my_awesome_widget');

AI Assistance: For help with creating widgets, you might ask:

“How do I create a custom widget in my WordPress plugin that [describe widget functionality]? Please provide the necessary class structure and registration code.”

11. Internationalization and Localization

To make your plugin translatable, use WordPress’s i18n functions:

// In your PHP files
__('Translatable string', 'my-awesome-plugin');
_e('Translatable string', 'my-awesome-plugin');

// Load text domain
function my_awesome_plugin_load_textdomain() {
    load_plugin_textdomain('my-awesome-plugin', false, dirname(plugin_basename(__FILE__)) . '/languages/');
}
add_action('plugins_loaded', 'my_awesome_plugin_load_textdomain');

AI Assistance: To learn more about internationalization, you can ask:

“Can you show me how to make my WordPress plugin translatable? Include examples of using translation functions and setting up language files.”

12. Security Considerations

Always validate and sanitize user input:

// Sanitize text input
$safe_text = sanitize_text_field($_POST['user_input']);

// Sanitize email
$safe_email = sanitize_email($_POST['user_email']);

// Escape output
echo esc_html($unsafe_text);

Use nonces for form submissions:

// Create a nonce
wp_nonce_field('my_awesome_action', 'my_awesome_nonce');

// Verify a nonce
if (isset($_POST['my_awesome_nonce']) && wp_verify_nonce($_POST['my_awesome_nonce'], 'my_awesome_action')) {
    // Process form data
}

AI Assistance: For guidance on security best practices, you might ask:

“What are some best practices for securing user input in a WordPress plugin? Can you provide examples of input sanitization and validation?”

13. Testing Your Plugin

Test your plugin thoroughly:

  1. Manual testing on different WordPress versions
  2. Automated testing using PHPUnit
  3. Testing with different themes and other plugins activated
  4. Check for PHP errors and warnings

AI Assistance: To develop a testing strategy, you can ask:

“Can you outline a testing strategy for my WordPress plugin? Include manual and automated testing approaches.”

14. Preparing for Distribution

Before distributing your plugin:

  1. Review and optimize your code
  2. Ensure all text is translatable
  3. Create a detailed readme.txt file
  4. Add a license (typically GPL for WordPress plugins)
  5. Create a changelog

AI Assistance: For help with preparing your plugin for distribution, you might ask:

“What steps should I take to prepare my WordPress plugin for distribution? Please provide a checklist of items to consider before submitting to the WordPress Plugin Directory.”

15. Submitting to the WordPress Plugin Directory

To submit your plugin to the WordPress.org Plugin Directory:

  1. Create a WordPress.org account
  2. Submit your plugin for review
  3. Wait for approval (can take several weeks)
  4. Once approved, upload your plugin

Remember to maintain and update your plugin regularly after publication.

AI Assistance: If you encounter issues during development or after publication, you can ask:

“I’m encountering [describe the issue] in my WordPress plugin. Can you help me diagnose the problem and suggest potential solutions?”

By following this guide and leveraging AI assistance when needed, you should now have a solid understanding of how to develop a WordPress plugin. Remember that plugin development is an iterative process, and you’ll learn more as you build and maintain your plugins. Happy coding!

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