WooCommerce Hooks & Filters

Before writing code

Fetch live docs:

1. Fetch https://developer.wordpress.org/plugins/hooks/ for WordPress Hooks fundamentals
2. Web-search site:developer.woocommerce.com hooks for WooCommerce-specific hooks
3. Web-search woocommerce action filter reference for comprehensive hook listings

How Hooks Work

Actions

Fire at specific points in execution — used for side effects (sending emails, writing logs, rendering HTML):

• do_action( 'hook_name', $arg1, $arg2 ) — fires the action
• add_action( 'hook_name', 'callback', $priority, $accepted_args ) — registers a listener
• remove_action( 'hook_name', 'callback', $priority ) — unregisters a listener
• Lower $priority = runs earlier (default 10)

Filters

Transform data as it flows through the system — must return a value:

• apply_filters( 'filter_name', $value, $arg1, $arg2 ) — applies the filter
• add_filter( 'filter_name', 'callback', $priority, $accepted_args ) — registers a filter
• Callback receives $value as first argument, must return the (possibly modified) value
• Chained: each filter's return value is the next filter's input

Priority

• Default: 10
• Lower numbers run first (1 before 10 before 99)
• Use early priorities (1–5) to modify data before others see it
• Use late priorities (20+) to act on fully-processed data

Key WooCommerce Hooks

Product Hooks

Cart Hooks

Checkout Hooks

Order Hooks

Admin Hooks

Lifecycle Hooks

Hook Patterns

Conditional Hook Registration

Register hooks only when needed:

• is_admin() — admin-only hooks
• wp_doing_ajax() — AJAX-only hooks
• is_checkout(), is_cart() — page-specific hooks

Class-Based Hook Registration

Use class methods as callbacks: add_action( 'hook', [ $this, 'method' ] ) or add_action( 'hook', [ __CLASS__, 'static_method' ] )

Removing WooCommerce Default Behavior

remove_action() / remove_filter() with the exact callback and priority that was used to add it. For class methods on singletons, reference the instance: remove_action( 'hook', [ WC()->structured_data, 'method' ] )

Dynamic Hook Names

WooCommerce uses dynamic hooks based on context:

• woocommerce_product_get_{$prop} — getter filter for any product property
• woocommerce_order_status_{$status} — status-specific action
• woocommerce_widget_{$widget_id}_args — widget-specific filter

Best Practices

• Always specify $accepted_args when your callback needs more than one argument
• Use late priorities when you need the final value (after other plugins have filtered)
• Prefer add_filter over directly modifying globals
• Use has_action() / has_filter() to check if a hook is already registered
• Never call do_action() / apply_filters() on WooCommerce core hooks from your code (fire your own hooks instead)
• Prefix your custom hook names: do_action( 'my_extension_after_process', $data )

Fetch the WooCommerce hook reference for current hook names, parameters, and deprecation notices before implementing.