Uninstall and cleanup hooks in Wordpress - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the uninstall hook in WordPress plugins?

The uninstall hook is used to clean up all plugin data like options, custom tables, and settings when the plugin is deleted, ensuring no leftover data remains.

beginner

Which file should contain the uninstall hook code in a WordPress plugin?

The uninstall hook code should be placed in an uninstall.php file or handled via register_uninstall_hook() in the main plugin file.

intermediate

How do you register an uninstall hook in a WordPress plugin?

Use register_uninstall_hook(__FILE__, 'function_name') in the main plugin file to specify the cleanup function to run on uninstall.

intermediate

Why should you avoid using deactivation hooks for cleanup tasks?

Deactivation hooks run when a plugin is turned off but not deleted, so cleanup here could remove data users want to keep. Cleanup belongs in uninstall hooks.

beginner

What kind of data should you remove in the uninstall hook?

Remove all plugin-created options, custom database tables, user meta, and files that are no longer needed to keep the site clean.

Where should you place the uninstall cleanup code in a WordPress plugin?

A In uninstall.php or via register_uninstall_hook()

B In the main plugin activation function

C Inside the plugin's stylesheet

D In the theme's functions.php file

Uninstall cleanup code belongs in uninstall.php or registered with register_uninstall_hook() to run only when the plugin is deleted.

What happens if you only use the deactivation hook for cleanup?

A Nothing happens on deactivation

B Data is removed only when plugin is deleted

C Data is removed when plugin is turned off, which may be unwanted

D Plugin automatically reactivates

Deactivation hook runs when plugin is turned off, so removing data here can cause loss if user just wants to pause the plugin.

Which function registers an uninstall hook in WordPress?

A add_filter('cleanup')

B register_uninstall_hook()

C register_deactivation_hook()

D add_action('uninstall')

register_uninstall_hook() is the correct function to register a cleanup function for plugin uninstall.

What kind of plugin data should NOT be left behind after uninstall?

A Theme files

B Plugin images used by other plugins

C WordPress core files

D Options, custom tables, user meta

Plugin-specific data like options and custom tables should be removed to avoid cluttering the database.

If a plugin does not have an uninstall hook, what happens when it is deleted?

A Plugin files are deleted but data remains in the database

B Plugin files and data are fully removed

C Plugin cannot be deleted

D WordPress crashes

Without an uninstall hook, only plugin files are deleted; data like options remain in the database.

Explain how to properly clean up plugin data when uninstalling a WordPress plugin.

Think about what happens when a plugin is deleted and how to remove all traces.

Describe the difference between deactivation and uninstall hooks in WordPress plugins.

Consider when each hook runs and what should happen to plugin data.