Filters and hooks

Discountline's rule types and conditions are registered, not hard-coded, so a plugin can add its own. Discountline Pro is built entirely on the hooks below.

Loading after Discountline

add_action( 'discountline_loaded', function () {
	// Discountline's classes are available here.
} );

discountline_loaded fires on plugins_loaded, only when WooCommerce is active. DISCOUNTLINE_VERSION, DISCOUNTLINE_FILE and DISCOUNTLINE_URL are defined.

Rule types

add_filter( 'discountline_rule_types', function ( $types ) {
	$types['half'] = array(
		'label'       => 'Half price',
		'description' => 'Every matching item at half price.',
		'icon'        => 'dashicons-star-half',
		'level'       => 'item',  // 'item', 'order' or '' (you apply it yourself)
		'badge'       => true,
	);
	return $types;
} );

add_filter( 'discountline_unit_price', function ( $price, $rule, $base, $qty ) {
	return 'half' === $rule->type() ? $base / 2 : $price;
}, 10, 4 );

• Item-level types give a price per item through discountline_unit_price (null: no change). The best price wins, as for Discountline's own types.
• Order-level types return what they save on the cart's items from discountline_order_saving ($saving, $rule, $items). Discountline applies it as an automatic coupon for that amount, by the rule's name; the best rule of each order-level type applies.
• discountline_rule_summary ($text, $rule) gives the one-line summary in the rule list, which is also the default badge.
• discountline_sanitize_rule ($data, $raw) cleans your type's own settings, stored in the rule's _discountline_rule meta.

Conditions

add_filter( 'discountline_conditions', function ( $conditions ) {
	$conditions['weekday'] = array(
		'default'  => '',                 // "off": must be empty or 'any'
		'sanitize' => 'sanitize_key',
		'check'    => function ( $day, $rule, $ctx ) {
			return strtolower( wp_date( 'D', $ctx->now ) ) === $day ? null : 'Not today.';
		},
		'cart'     => false,              // true: only judged with a cart
	);
	return $conditions;
} );

Conditions are checked in array order; the first one that returns a reason stops the rule, and the reason is the text a store owner sees. section can be 'limits' for usage limits. The value lives in the rule's settings under conditions (or limits).

A rule whose type, or one of whose conditions, no active plugin registers is kept as it is but never applies, and is listed as needing Discountline Pro. That's why a condition's "off" value must be empty or 'any': it lets Discountline tell an unused condition from one in use.

The rule editor

Hook	Use
discountline_editor_sections (filter)	Boxes of the editor, id => title. Your box is a form table filled by the next hook.
discountline_editor_rows (action)	$section, $rule: print <tr> rows at the end of a box. Rows only for some types: <tr class="discountline-only" data-for="half">. Name fields discountline[...].
discountline_summary_box (action)	$post: markup after the Summary box's contents.
discountline_rule_status (filter)	$html, $rule: a status pill for the list instead of "Active"; use RuleEditor::pill( $text, 'later' ).
discountline_settings (filter)	The fields of the Discount rules settings section.
discountline_show_tier_table (filter)	$show, $product: whether a product page shows its quantity tier table. Return false to leave it out, e.g. for shoppers who can't see prices.

The Summary box is written by rule-editor.js; add to it on the discountline-summary jQuery event on document. It gets one object, { type, lines, rows, notes, helpers }: push lines for your type, notes for your conditions, or splice rows.

Styling

Class	Element
discountline-badge	The badge after a price
discountline-tiers	The price table; tr.is-current is the tier for the chosen quantity
discountline-saving	"You save …" under the table
discountline-automatic	Automatic discounts under the Discount row in the Cart and Checkout blocks