Extension uninstall.php

When someone deletes an extension from Unyson+ → Extensions, the framework looks for an uninstall.php in the extension's folder and runs it just before it deletes the folder. It works the same way as a WordPress plugin's uninstall.php.

It is a file rather than a hook because the extension may be inactive when it is deleted, and an inactive extension's code is never loaded. This file is the last moment its code exists.

The rules

• Check the constant first. FW_EXTENSION_UNINSTALL is defined only while the framework runs the file. Return straight away without it, so the file does nothing if it is ever loaded any other way.
• Don't rely on your own classes. The extension may not have been loaded, so write the file to stand alone: plain WordPress functions and $wpdb.
• Ask before deleting. Most people who delete an extension reinstall it. Delete stored data only when the site owner opted in, usually with a setting. Your settings are in the option fw_ext_settings_options:<extension-name>.
• Multisite: loop over the sites and check each site's own setting.
• A fatal error or exception in the file is caught, and the uninstall carries on. Leftover data is better than a half-deleted extension.

Two variables are available: $fw_extension_name (the extension's name) and $fw_uninstall_file.

Example

framework/extensions/my-extension/uninstall.php

<?php
if ( ! defined( 'FW_EXTENSION_UNINSTALL' ) ) {
	return;
}

$my_cleanup = static function () {
	global $wpdb;

	$settings = get_option( 'fw_ext_settings_options:my-extension', [] );

	if ( empty( $settings['delete_on_uninstall'] ) ) {
		return; // The owner did not ask for it.
	}

	delete_option( 'fw_ext_settings_options:my-extension' );
	$wpdb->query( $wpdb->prepare(
		"DELETE FROM {$wpdb->postmeta} WHERE meta_key LIKE %s",
		$wpdb->esc_like( '_my_extension_' ) . '%'
	) );
	wp_clear_scheduled_hook( 'my_extension_cron' );
};

if ( is_multisite() ) {
	foreach ( get_sites( [ 'fields' => 'ids', 'number' => 0 ] ) as $blog_id ) {
		switch_to_blog( $blog_id );
		$my_cleanup();
		restore_current_blog();
	}
} else {
	$my_cleanup();
}

The SEO extension's uninstall.php is a complete working example; see Access and removal for what it removes.

When it does not run

• Deactivating an extension never runs it.
• Updating the plugin replaces the extension folders without running it.
• Deleting the extension folder by hand (FTP, a file manager) skips it, as it would for a plugin.