Uninstall and cleanup hooks in Wordpress - Mini Project: Build & Apply

WordPress Plugin Uninstall and Cleanup Hooks

📖 Scenario: You have created a WordPress plugin that stores some settings and creates a custom database table. Now you want to make sure that when the plugin is uninstalled, all its data is cleaned up properly.

🎯 Goal: Build a WordPress plugin that uses the uninstall hook to remove plugin options and drop the custom database table when the plugin is uninstalled.

📋 What You'll Learn

Create an array called $my_plugin_options with exact keys and values

Create a variable called $table_name with the exact table name

Write a function called my_plugin_uninstall that deletes all options in $my_plugin_options and drops the table $table_name

Register the uninstall hook using register_uninstall_hook with the function my_plugin_uninstall

💡 Why This Matters

🌍 Real World

Plugins often store data in the database. Cleaning up on uninstall prevents leftover clutter and keeps the site clean.

💼 Career

Knowing how to properly use uninstall hooks is essential for WordPress plugin developers to maintain good plugin hygiene and user trust.

1

Setup plugin options and table name

Create an array called $my_plugin_options with these exact keys and values: 'setting_one' => 'value1', 'setting_two' => 'value2'. Also create a variable called $table_name and set it to $wpdb->prefix . 'my_plugin_table'.

Wordpress

<?php
global $wpdb;
# Create $my_plugin_options array and $table_name variable here

Need a hint?

Use array() to create $my_plugin_options and concatenate $wpdb->prefix with the table name for $table_name.

2

Define the uninstall function

Write a function called my_plugin_uninstall that uses global $wpdb. Inside it, loop over $my_plugin_options keys and delete each option using delete_option. Then drop the table $table_name using $wpdb->query with the SQL DROP TABLE IF EXISTS.

Wordpress

 'value1', 'setting_two' => 'value2');
$table_name = $wpdb->prefix . 'my_plugin_table';

# Define function my_plugin_uninstall here

Need a hint?

Use foreach to loop over the keys of $my_plugin_options and call delete_option for each. Use $wpdb->query to drop the table.

3

Register the uninstall hook

Use register_uninstall_hook with __FILE__ and the function name 'my_plugin_uninstall' to register the uninstall cleanup.

Wordpress

 'value1', 'setting_two' => 'value2');
$table_name = $wpdb->prefix . 'my_plugin_table';

function my_plugin_uninstall() {
    global $wpdb;
    global $my_plugin_options, $table_name;
    foreach (array_keys($my_plugin_options) as $option_name) {
        delete_option($option_name);
    }
    $wpdb->query("DROP TABLE IF EXISTS $table_name");
}

# Register uninstall hook here

Need a hint?

Call register_uninstall_hook with __FILE__ and the uninstall function name as a string.

4

Add plugin header comment

Add the WordPress plugin header comment at the top of the file with these exact lines: Plugin Name: My Cleanup Plugin, Description: A plugin that cleans up on uninstall, Version: 1.0, Author: Your Name.

Wordpress

# Add the plugin header comment at the top of the file
 'value1', 'setting_two' => 'value2');
$table_name = $wpdb->prefix . 'my_plugin_table';

function my_plugin_uninstall() {
    global $wpdb;
    global $my_plugin_options, $table_name;
    foreach (array_keys($my_plugin_options) as $option_name) {
        delete_option($option_name);
    }
    $wpdb->query("DROP TABLE IF EXISTS $table_name");
}

register_uninstall_hook(__FILE__, 'my_plugin_uninstall');

Need a hint?

The plugin header comment must be at the very top of the file inside /* ... */.