WooCommerce powers huge stores. Scaling it requires specific knowledge about how it handles sessions, orders, and product data.
1. Why is caching tricky with WooCommerce?
Answer: You cannot cache dynamic pages like Cart, Checkout, and My Account.
- Cookie Exclusion: Caching rules must exclude pages where the `woocommerce_items_in_cart` cookie is present.
- Fragment Caching: For the "Mini Cart" in the header, use AJAX to load it dynamically so the rest of the page can remain cached static HTML.
2. What is HPOS (High Performance Order Storage)?
Answer: A major architectural change in WooCommerce.
- Old Way: Orders were stored in `wp_posts` and `wp_postmeta`. This was slow and bloated the main content tables.
- HPOS: Orders are stored in custom, dedicated tables (`wc_orders`, `wc_order_addresses`, etc.).
- Benefit: Massive performance gain (up to 30% faster) and better scalability.
3. How do you customize the Checkout process?
Answer:
- Hooks: Use actions like `woocommerce_before_checkout_form` or filters like `woocommerce_checkout_fields` to add/remove fields.
- Templates: Override `checkout/form-checkout.php` (use sparingly).
- Blocks: The new Cart & Checkout Blocks allow React-based customization.
4. How do you handle inventory synchronization with an ERP?
Answer: Usually via a scheduled task (CRON) or Webhooks.
- Inbound (ERP -> Woo): A script runs every X minutes, fetches stock levels from ERP API, and updates WooCommerce products via CRUD methods (`$product->set_stock_quantity()`).
- Outbound (Woo -> ERP): Hook into `woocommerce_payment_complete` to send order data to the ERP immediately.
5. What is the difference between Simple, Variable, and Grouped products?
Answer:
- Simple: Single item, one price, one SKU.
- Variable: A product with variations (Size, Color). Each variation is technically a child post with its own price, stock, and SKU.
- Grouped: A collection of simple products sold together on one page.
6. How do you use the WooCommerce REST API for bulk updates?
Answer: The REST API supports batch processing, which is essential for syncing large catalogs from an ERP.
Endpoint: /wp-json/wc/v3/products/batch
Payload: You can send arrays of `create`, `update`, and `delete` objects in a single HTTP POST request. This significantly reduces network overhead compared to making individual requests for each product.
7. What is the correct way to override WooCommerce templates?
Answer:
- Copy: Copy the file from `wp-content/plugins/woocommerce/templates/{path}`.
- Paste: Paste it into `wp-content/themes/{your-theme}/woocommerce/{path}`.
- Maintenance: You must monitor the "System Status" page after WooCommerce updates. If the core template changes, your overridden file might become outdated (out of date version), requiring you to manually merge changes.
8. How do you add a custom field to the Product General Tab?
Answer: You need to hook into the product data tabs and then save the data.
- Display: Use `woocommerce_product_options_general_product_data` action to output the field using `woocommerce_wp_text_input()`.
- Save: Use `woocommerce_process_product_meta` action to save the `$_POST` value to post meta using `update_post_meta()`.