Wp Plugin Development

// Check if plugin is loaded as must-use
if ( strpos( __FILE__, WPMU_PLUGIN_DIR ) !== false ) {
    // Running as must-use plugin - skip activation hooks
}

// Drop-ins are in wp-content/ root, not plugins/
// Check filename against known drop-in names
$drop_ins = array( 'object-cache.php', 'db.php', 'advanced-cache.php', 'db-error.php', 'maintenance.php' );

<?php
/**
 * Plugin Name: My Plugin
 */

<?php
/**
 * Plugin Name: My Awesome Plugin
 * Plugin URI: https://example.com/my-awesome-plugin
 * Description: Does amazing things with WordPress
 * Version: 1.0.0
 * Requires at least: 6.0
 * Requires PHP: 7.4
 * Author: John Doe
 * Author URI: https://example.com
 * License: GPL v2 or later
 * License URI: https://www.gnu.org/licenses/gpl-2.0.html
 * Text Domain: my-awesome-plugin
 * Domain Path: /languages
 */

if ( ! defined( 'ABSPATH' ) ) {
    exit; // Exit if accessed directly
}

<?php
function save_settings() {
    update_option( 'plugin_settings', $_POST['data'] );
}

class Plugin_Settings {
    // ...
}

add_action( 'admin_init', 'save_settings' );

<?php
function mypl_save_settings() {
    update_option( 'mypl_settings', $_POST['data'] );
}

class MyPL_Settings {
    // ...
}

add_action( 'admin_init', 'mypl_save_settings' );

<?php
namespace MyPlugin\Admin;

function save_settings() {
    update_option( 'mypl_settings', $_POST['data'] ); // Still prefix option names
}

class Settings {
    // ...
}

add_action( 'admin_init', __NAMESPACE__ . '\save_settings' );

<?php
// Plugin registers CPT on init but never flushes rewrites
add_action( 'init', 'mypl_register_cpt' );

function mypl_register_cpt() {
    register_post_type( 'mypl_book', array( /* args */ ) );
}

<?php
// Main plugin file: my-plugin.php

// Activation hook
register_activation_hook( __FILE__, 'mypl_activate' );

function mypl_activate() {
    // Set default options
    add_option( 'mypl_version', '1.0.0' );

    // Register CPT before flushing
    mypl_register_cpt();

    // Flush rewrite rules ONLY on activation
    flush_rewrite_rules();
}

// Deactivation hook
register_deactivation_hook( __FILE__, 'mypl_deactivate' );

function mypl_deactivate() {
    // Clear transients
    delete_transient( 'mypl_cache' );

    // Flush rewrite rules
    flush_rewrite_rules();
}

// Init hook for normal operation
add_action( 'init', 'mypl_register_cpt' );

function mypl_register_cpt() {
    register_post_type( 'mypl_book', array( /* args */ ) );
}

// Uninstall file: uninstall.php
if ( ! defined( 'WP_UNINSTALL_PLUGIN' ) ) {
    exit;
}

// Delete all plugin data
delete_option( 'mypl_version' );
delete_option( 'mypl_settings' );

// Drop custom table
global $wpdb;
$wpdb->query( "DROP TABLE IF EXISTS {$wpdb->prefix}mypl_data" );

<?php
add_action( 'init', 'mypl_register_cpt' );

function mypl_register_cpt() {
    register_post_type( 'book', array( // Missing prefix, no show_in_rest
        'public' => true,
    ) );

    flush_rewrite_rules(); // CRITICAL: Runs on EVERY page load
}

<?php
add_action( 'init', 'mypl_register_cpt_and_taxonomy' );

function mypl_register_cpt_and_taxonomy() {
    // Register custom post type (max 20 chars, prefixed)
    register_post_type(
        'mypl_book',
        array(
            'labels'       => array(
                'name'          => __( 'Books', 'my-plugin' ),
                'singular_name' => __( 'Book', 'my-plugin' ),
            ),
            'public'       => true,
            'has_archive'  => true,
            'rewrite'      => array( 'slug' => 'books' ),
            'supports'     => array( 'title', 'editor', 'thumbnail' ),
            'show_in_rest' => true, // Gutenberg support
        )
    );

    // Register custom taxonomy (max 32 chars, prefixed)
    register_taxonomy(
        'mypl_genre',
        'mypl_book',
        array(
            'labels'       => array(
                'name'          => __( 'Genres', 'my-plugin' ),
                'singular_name' => __( 'Genre', 'my-plugin' ),
            ),
            'hierarchical' => true,
            'public'       => true,
            'show_in_rest' => true, // Gutenberg support
        )
    );
}

// Flush rewrites ONLY on activation
register_activation_hook( __FILE__, 'mypl_activate' );

function mypl_activate() {
    mypl_register_cpt_and_taxonomy(); // Register first
    flush_rewrite_rules(); // Then flush (only once)
}

register_deactivation_hook( __FILE__, 'mypl_deactivate' );

function mypl_deactivate() {
    flush_rewrite_rules(); // Clean up rewrite rules
}

<?php
add_action( 'admin_init', 'mypl_settings_init' );

function mypl_settings_init() {
    add_settings_section( 'mypl_section', 'Settings', null, 'mypl-settings' );

    add_settings_field(
        'mypl_api_key',
        'API Key',
        'mypl_api_key_callback',
        'mypl-settings',
        'mypl_section'
    );
    // Missing register_setting() - field won't save!
}

<?php
add_action( 'admin_init', 'mypl_register_settings' );

function mypl_register_settings() {
    // 1. Register setting (declares option name and sanitization)
    register_setting(
        'mypl_options_group',    // Option group
        'mypl_settings',          // Option name
        array(
            'type'              => 'array',
            'sanitize_callback' => 'mypl_sanitize_settings',
            'default'           => array(
                'api_key' => '',
                'enabled' => false,
            ),
        )
    );

    // 2. Add settings section
    add_settings_section(
        'mypl_main_section',
        __( 'Main Settings', 'my-plugin' ),
        'mypl_section_callback',
        'mypl-settings'
    );

    // 3. Add settings fields
    add_settings_field(
        'mypl_api_key',
        __( 'API Key', 'my-plugin' ),
        'mypl_api_key_callback',
        'mypl-settings',
        'mypl_main_section'
    );

    add_settings_field(
        'mypl_enabled',
        __( 'Enable Feature', 'my-plugin' ),
        'mypl_enabled_callback',
        'mypl-settings',
        'mypl_main_section'
    );
}

function mypl_section_callback() {
    echo '<p>' . esc_html__( 'Configure your plugin settings below.', 'my-plugin' ) . '</p>';
}

function mypl_api_key_callback() {
    $options = get_option( 'mypl_settings' );
    $value = isset( $options['api_key'] ) ? $options['api_key'] : '';
    ?>
    <input type="text"
           name="mypl_settings[api_key]"
           value="<?php echo esc_attr( $value ); ?>"
           class="regular-text">
    <?php
}

function mypl_enabled_callback() {
    $options = get_option( 'mypl_settings' );
    $checked = isset( $options['enabled'] ) && $options['enabled'];
    ?>
    <input type="checkbox"
           name="mypl_settings[enabled]"
           value="1"
           <?php checked( $checked, true ); ?>>
    <?php
}

function mypl_sanitize_settings( $input ) {
    $sanitized = array();

    if ( isset( $input['api_key'] ) ) {
        $sanitized['api_key'] = sanitize_text_field( $input['api_key'] );
    }

    $sanitized['enabled'] = isset( $input['enabled'] ) && $input['enabled'] ? true : false;

    return $sanitized;
}

// Settings page HTML
function mypl_settings_page() {
    if ( ! current_user_can( 'manage_options' ) ) {
        return;
    }
    ?>
    <div class="wrap">
        <h1><?php echo esc_html( get_admin_page_title() ); ?></h1>
        <form method="post" action="options.php">
            <?php
            // Output nonce, action, option_page fields
            settings_fields( 'mypl_options_group' );

            // Output sections and fields
            do_settings_sections( 'mypl-settings' );

            submit_button();
            ?>
        </form>
    </div>
    <?php
}

<?php
add_filter( 'the_content', 'mypl_modify_content' );

function mypl_modify_content( $content ) {
    if ( is_single() ) {
        $content .= '<p>Footer text</p>';
    }
    // Missing return! Fatal error.
}

<?php
// Action with priority (runs before core at priority 10)
add_action( 'init', 'mypl_register_cpt', 9 );

function mypl_register_cpt() {
    register_post_type( 'mypl_book', array( /* args */ ) );
}

// Filter with return (CRITICAL)
add_filter( 'the_content', 'mypl_modify_content', 10, 1 );

function mypl_modify_content( $content ) {
    if ( is_single() ) {
        $content .= '<p>Footer text</p>';
    }
    return $content; // ALWAYS return in filters
}

// Multiple parameters with accepted_args
add_filter( 'wp_mail', 'mypl_modify_email', 10, 1 );

function mypl_modify_email( $args ) {
    $args['from'] = 'Custom <custom@example.com>';
    return $args;
}

// Removing hooks (MUST match exact registration params)
add_action( 'wp_footer', 'mypl_footer_code', 15 );

// To remove: priority must match
remove_action( 'wp_footer', 'mypl_footer_code', 15 );

// Create custom hooks for extensibility
function mypl_process_data( $data ) {
    // Allow other plugins to modify data
    $data = apply_filters( 'mypl_before_process', $data );

    // Process data
    $result = process( $data );

    // Allow other plugins to hook after processing
    do_action( 'mypl_after_process', $result );

    return $result;
}

<?php
$count = 5;
echo __( "You have $count messages", 'my-plugin' ); // Breaks translation extraction

// Missing text domain
echo __( 'Save Settings' );

// Text domain mismatch
// Plugin folder: my-awesome-plugin
echo __( 'Save', 'my_plugin' ); // Underscore instead of dash

<?php
// Basic translation with text domain
echo __( 'Settings saved successfully', 'my-awesome-plugin' );

// Translation with echo
_e( 'Click here to continue', 'my-awesome-plugin' );

// Placeholders with sprintf (NOT embedded variables)
$count = 5;
echo sprintf(
    __( 'You have %d messages', 'my-awesome-plugin' ),
    $count
);

// Pluralization with _n()
echo sprintf(
    _n(
        'One post found',
        '%d posts found',
        $count,
        'my-awesome-plugin'
    ),
    number_format_i18n( $count )
);

// Context-aware translation with _x()
echo _x( 'Post', 'noun - blog post', 'my-awesome-plugin' );
echo _x( 'Post', 'verb - submit', 'my-awesome-plugin' );

// Escaped output + translation
echo '<h1>' . esc_html__( 'Welcome', 'my-awesome-plugin' ) . '</h1>';
echo '<input placeholder="' . esc_attr__( 'Enter your name', 'my-awesome-plugin' ) . '">';

// Load text domain on init (optional in WP 4.6+)
add_action( 'init', 'mypl_load_textdomain' );

function mypl_load_textdomain() {
    load_plugin_textdomain(
        'my-awesome-plugin',
        false,
        dirname( plugin_basename( __FILE__ ) ) . '/languages'
    );
}

<?php
add_action( 'rest_api_init', 'mypl_register_routes' );

function mypl_register_routes() {
    register_rest_route( 'mypl/v1', '/posts', array(
        'methods'  => 'GET',
        'callback' => 'mypl_get_posts',
        // Missing: 'permission_callback' (WordPress 5.5+ blocks this)
    ) );
}

<?php
add_action( 'rest_api_init', 'mypl_register_routes' );

function mypl_register_routes() {
    // Public read-only endpoint
    register_rest_route(
        'mypl/v1', // Namespace with version
        '/posts',
        array(
            'methods'             => 'GET',
            'callback'            => 'mypl_get_posts',
            'permission_callback' => '__return_true', // Explicitly public (OK for read-only)
            'args'                => array(
                'per_page' => array(
                    'default'           => 10,
                    'sanitize_callback' => 'absint',
                    'validate_callback' => function( $param ) {
                        return is_numeric( $param ) && $param > 0 && $param <= 100;
                    },
                ),
            ),
        )
    );

    // Protected write endpoint
    register_rest_route(
        'mypl/v1',
        '/posts/(?P<id>\d+)',
        array(
            'methods'             => 'DELETE',
            'callback'            => 'mypl_delete_post',
            'permission_callback' => function() {
                return current_user_can( 'delete_posts' );
            },
            'args'                => array(
                'id' => array(
                    'validate_callback' => function( $param ) {
                        return is_numeric( $param );
                    },
                ),
            ),
        )
    );
}

function mypl_get_posts( $request ) {
    $per_page = $request->get_param( 'per_page' );
    $posts = get_posts( array( 'posts_per_page' => $per_page ) );
    return rest_ensure_response( $posts );
}

function mypl_delete_post( $request ) {
    $post_id = $request->get_param( 'id' );
    $result = wp_delete_post( $post_id, true );

    if ( ! $result ) {
        return new WP_Error(
            'delete_failed',
            __( 'Failed to delete post', 'my-plugin' ),
            array( 'status' => 500 )
        );
    }

    return rest_ensure_response( array( 'deleted' => true, 'id' => $post_id ) );
}

<?php
// Authenticated users
add_action( 'wp_ajax_mypl_save_data', 'mypl_save_data_callback' );

// Public (non-authenticated)
add_action( 'wp_ajax_nopriv_mypl_save_data', 'mypl_save_data_callback' );

function mypl_save_data_callback() {
    // Security checks (see wp-security-review for depth)
    check_ajax_referer( 'mypl_nonce', 'nonce' );

    if ( ! current_user_can( 'edit_posts' ) ) {
        wp_send_json_error( 'Insufficient permissions' );
    }

    $data = sanitize_text_field( $_POST['data'] );

    // Process data
    update_option( 'mypl_data', $data );

    wp_send_json_success( 'Data saved' );
}

<?php
add_action( 'wp_enqueue_scripts', 'mypl_enqueue_admin_assets' );

function mypl_enqueue_admin_assets() {
    // Admin assets loading on public pages (unnecessary)
    wp_enqueue_script( 'mypl-admin', plugin_dir_url( __FILE__ ) . 'admin.js' );
}

<?php
// Only load admin code in admin context
if ( is_admin() ) {
    require_once plugin_dir_path( __FILE__ ) . 'admin/class-admin.php';
}

// Admin-specific assets
add_action( 'admin_enqueue_scripts', 'mypl_enqueue_admin_assets' );

function mypl_enqueue_admin_assets() {
    wp_enqueue_script(
        'mypl-admin',
        plugin_dir_url( __FILE__ ) . 'admin/admin.js',
        array( 'jquery' ),
        '1.0.0',
        true
    );
}

// Public-facing assets
add_action( 'wp_enqueue_scripts', 'mypl_enqueue_public_assets' );

function mypl_enqueue_public_assets() {
    wp_enqueue_script(
        'mypl-public',
        plugin_dir_url( __FILE__ ) . 'public/public.js',
        array( 'jquery' ),
        '1.0.0',
        true
    );
}

<?php
// Function existence check
if ( ! function_exists( 'mypl_init' ) ) {
    function mypl_init() {
        // Plugin initialization
    }
}

// Class existence check
if ( ! class_exists( 'MyPL_Plugin' ) ) {
    class MyPL_Plugin {
        // Plugin class
    }
}

# WordPress Plugin Review: my-awesome-plugin

## FILE: my-awesome-plugin.php

### Line 15: CRITICAL - Missing ABSPATH check
Direct file access possible. Add ABSPATH check at top of all PHP files.

❌ BAD:
<?php
/**
 * Plugin Name: My Plugin
 */

function mypl_init() { ... }

✅ GOOD:
<?php
/**
 * Plugin Name: My Plugin
 */

if ( ! defined( 'ABSPATH' ) ) {
    exit;
}

function mypl_init() { ... }

### Line 45: WARNING - Missing text domain in i18n call
Translation won't work. Always include text domain parameter.

❌ BAD:
echo __( 'Save Settings' );

✅ GOOD:
echo __( 'Save Settings', 'my-awesome-plugin' );

## FILE: includes/class-cpt.php

### Line 23: CRITICAL - flush_rewrite_rules on init hook
Expensive DB write on every page load. Move to activation hook.

❌ BAD:
add_action( 'init', 'mypl_register_cpt' );

function mypl_register_cpt() {
    register_post_type( 'book', array( /* ... */ ) );
    flush_rewrite_rules(); // Runs on EVERY request
}

✅ GOOD:
add_action( 'init', 'mypl_register_cpt' );

function mypl_register_cpt() {
    register_post_type( 'mypl_book', array( /* ... */ ) );
}

register_activation_hook( __FILE__, 'mypl_activate' );

function mypl_activate() {
    mypl_register_cpt();
    flush_rewrite_rules(); // Only on activation
}

## SUMMARY

**Total issues: 15**
- CRITICAL: 4 (must fix for WordPress.org submission)
- WARNING: 8 (non-standard patterns)
- INFO: 3 (best practice improvements)

**WordPress.org readiness:** NOT READY - 4 critical issues block submission

**Security note:** This review focused on plugin architecture and WordPress.org compliance. Security issues detected (missing nonce in AJAX handler, unsanitized input in form). Run `/wp-sec-review` for comprehensive security analysis.

wp plugin install plugin-check --activate
wp plugin check my-plugin.php