Extra Price hooks

Extra Price gives each choice a price of its own and adds the total to the product. Its hooks fall into four groups: how the subtotal is calculated, how prices are displayed in the configurator, how they appear in the cart and order, and the formula engine used by the calculation field.

See the hook reference index for how to register PHP and JavaScript callbacks.

PHP filters

PHP actions

JavaScript filters

JavaScript actions

pc.get_extra_price

The single most useful JavaScript filter here. It runs at the very end of the per-choice price calculation, after the amount/percentage type has been resolved, and everything else — subtotal, display, cart preview — is built on its result.

wp.hooks.addFilter( 'pc.get_extra_price', 'my-plugin/ep', function ( price, choice, context ) {	// A surcharge on oversized options.	if ( choice.get( 'my_oversized' ) ) {		return price + 25;	}	return price;} );

context identifies where the price is being asked for, so you can price a choice differently in the summary than in the toolbar. Return a number, never a formatted string.

PC.fe.extra_price.item_price and the subtotal filters

These run in a fixed order each time the total is recalculated:

1. PC.fe.extra_price.before.add.extra_price — action, per choice, fires for inactive choices too
2. PC.fe.extra_price.item_price — filter, per active choice
3. PC.fe.extra_price.subtotal.before_apply_taxes — filter, once
4. (taxes applied)
5. PC.fe.extra_price.subtotal — filter, once
6. PC.fe.extra_price.after.setSubTotal — action, once, with the base price and subtotal

Use item_price to change what one choice contributes, and subtotal for something that applies to the order as a whole:

// Volume discount on the configured extras.wp.hooks.addFilter( 'PC.fe.extra_price.subtotal', 'my-plugin/ep', function ( subtotal ) {	return subtotal > 500 ? subtotal * 0.95 : subtotal;} );

Applying a discount in subtotal rather than subtotal.before_apply_taxes means it is applied after tax — pick the one that matches how the store's prices are entered.

PC.fe.show.extra_price

Decides whether the price element is rendered at all. The third argument is 'choice-item' in the toolbar and 'summary-item' in the summary.

wp.hooks.addFilter(	'PC.fe.show.extra_price',	'my-plugin/ep',	function ( show, choice, context ) {		return 'summary-item' === context ? false : show;	});

PC.fe.extra_price.formula_callbacks

The calculation field evaluates a formula in the browser. This filter supplies the functions that formula may call, on top of anything already on PC.fe.formula_callbacks.

wp.hooks.addFilter(	'PC.fe.extra_price.formula_callbacks',	'my-plugin/ep',	function ( callbacks, formulaModel, options ) {		callbacks.shipping_band = function ( weight ) {			return weight > 20 ? 45 : 15;		};		return callbacks;	});

Reference it in a formula as {function:shipping_band(...)}. Keep these functions pure and fast — they run on every recalculation.

formula_with_values

The formula after every {layer} and {function:…} placeholder has been substituted, and just before any remaining unmatched braces are replaced with 0. This is the last point at which you can rewrite the expression.

wp.hooks.addFilter(	'formula_with_values',	'my-plugin/ep',	function ( resolved, formula, formulaModel, dataType ) {		return resolved;	});

Logging resolved here is the fastest way to debug a formula that returns an unexpected number.

mkl_pc/math-expression-evaluator/token_definitions

The PHP counterpart: it registers functions with the expression evaluator so they exist in the browser. Each entry needs a JavaScript body, a signature and a description — the description is shown to the shop manager in the formula field's help.

add_filter( 'mkl_pc/math-expression-evaluator/token_definitions', function ( $tokens ) {	$tokens[] = array(		'type'        => 3,		'token'       => 'vat',		'show'        => true,		'value'       => 'function( a ) { return a * 1.2; }',		'signature'   => 'vat(value)',		'description' => __( 'adds 20% VAT to value.', 'my-plugin' ),	);	return $tokens;} );

Return an array. Returning anything else makes the plugin fall back to an empty token list, which silently breaks every formula on the site.

mkl_pc/extra_price/add_extra_price and mkl_pc/extra_price/qty

Server-side equivalents of the frontend subtotal filters, applied when the cart total is recalculated. add_extra_price returning false skips a choice entirely; qty multiplies it.

// Charge engraving once, no matter how many units are ordered.add_filter( 'mkl_pc/extra_price/qty', function ( $qty, $layer, $cart_item ) {	return 'engraving' === $layer->get_layer( 'name' ) ? 1 : $qty;}, 10, 3 );

These decide what the customer actually pays — the JavaScript filters only decide what they see. Change them in pairs, or the displayed price and the charged price will disagree.

mkl_pc/extra_price/price_to_display and the order meta filters

Control how a choice's price reads in the cart, the order and emails. The default renders as ( + £12.00 ); the three markup filters supply the (, the ) and the +.

add_filter( 'mkl_pc_extra_price_order_item_meta__before_price', function () {	return '— ';} );add_filter( 'mkl_pc_extra_price_order_item_meta__after_price', function () {	return '';} );

By default a zero price prints nothing at all; return true from mkl_pc_extra_price_order_item_meta__display_null_price to show "included" style rows.

hide_item_extra_price_in_cart and mkl_pc/extra_price/hide_extra_price_meta

Two levels of suppression. The first mirrors the plugin setting and hides every per-choice price in the cart; the second is per line item and receives the layer and item key.

add_filter( 'mkl_pc/extra_price/hide_extra_price_meta', function ( $hide, $layer, $item_key ) {	return 'internal' === $layer->get_layer( 'name' ) ? true : $hide;}, 10, 3 );

mkl_pc/extra_price/relative_price

When relative pricing is on, each choice shows the difference from the currently selected one rather than its absolute price. This filter overrides the site setting per request.

add_filter( 'mkl_pc/extra_price/relative_price', function ( $relative ) {	return is_user_logged_in() ? $relative : false;} );

mkl_pc/extra_price/get_tax_rates and mkl_pc/extra_price/before_get_tax_rates

The configurator fetches tax rates over AJAX so it can price choices correctly in the browser. The action fires before rates are resolved — the place to switch the customer object — and the filter shapes the payload that is returned.

add_action( 'mkl_pc/extra_price/before_get_tax_rates', function ( $product, $customer ) {	// e.g. force a location before WC_Tax::get_rates() runs}, 10, 2 );add_filter( 'mkl_pc/extra_price/get_tax_rates', function ( $tax_data, $product ) {	return $tax_data;}, 10, 2 );

tmpl-mkl-pc-extra-price--before and --after

Template hooks around the price markup. They print Underscore template syntax — see Template hooks are different.

add_action( 'tmpl-mkl-pc-extra-price--after', function () { ?>	<# if ( data.on_sale ) { #><span class="sale-flag">Sale</span><# } #><?php } );

PC.ExtraPrice.view.data and PC.ExtraPrice.view.extra_price_to_display

The price view's own hooks: the first filters the object handed to the template (useful with the template hooks above), the second filters the number just before it is formatted as money.

mkl_pc/math-expression-evaluator/tokens

Internal. A legacy escape hatch that injects a raw inline script to register evaluator tokens. Use mkl_pc/math-expression-evaluator/token_definitions instead.

Related hooks from other plugins

extra_price_overrides_product_price is shared with Linked Product Stock Management. PC.fe.extra_price.after.get_tax_rates is fired by the core plugin. The add-on also filters WooCommerce's woocommerce_get_price_including_tax, woocommerce_get_price_excluding_tax and woocommerce_adjust_non_base_location_prices.