WC_Query data store query processing demo implementation

wc-query-demo-data-store.php

<?php

class WC_Data_Store_WP {

	// . . .

	/**
	 * Map WC_Query args into a format that WP_Query can parse.
	 * @param $args - array of query args from a WC_Query.
	 * @return array of query args that WP_Query can parse.
	 * @todo not a big fan of this method's name.
	 */
	protected function get_automapped_wp_query_args( $args ) {
		
		// Start with empty default WP_Query args.
		$query_args = new WP_Query()->fill_query_vars( array() );

		foreach( $args as $key => $value ) {

			if ( '' === $value || array() === $value ) {
				continue;
			}

			// Handle standard WP_Query args.
			if ( isset( $query_args[ $key ] ) && 'meta_query' !== $key ) {
				$query_args[ $key ] = $value;
				continue;
			}

			// Generate meta queries for internal keys stored in metadata.
			// This will automatically handle 'width', 'downloadable', 'usage_limit', etc.
			if ( isset( $this->internal_meta_keys[ '_' . $key ] ) ) {
				if ( ! isset( $query_args['meta_query'] ) ) {
					$query_args['meta_query'] = array();
				}

				$query_args['meta_query'][] = array(
					'key'     => '_' . $key,
					'value'   => $value,
					'compare' => 'LIKE', // Use '=' instead?
				);
			}
		}

		// Handle custom user-specified meta queries.
		if ( isset( $args['meta_query'] ) ) {
			if ( ! isset( $query_args['meta_query'] ) ) {
				$query_args['meta_query'] = $args['meta_query'];
			} else {
				$query_args['meta_query'][] = $args['meta_query'];
			}
		}

		return $query_args;
	}

	// . . .
}

class WC_Product_Data_Store_CPT {

	// . . .

	public function get_products( $args ) {

		$wp_query_args = $this->get_automapped_wp_query_args( $args );

                // Process special-case args that can't automatically be parsed by get_automapped_wp_query_args
		if ( ! empty( $args['category'] ) ) {
			unset( $wp_query_args['category'] );
			$wp_query_args['tax_query'][] = array(
				'taxonomy' => 'product_cat',
				'field'    => 'slug',
				'terms'   => $args['category'],
			);
		}

		if ( ! empty( $args['shipping_class'] ) ) {
			$wp_query_args['tax_query'][] = array(
				'taxonomy' => 'product_shipping_class',
				'field'    => 'slug',
				'terms'   => $args['shipping_class'],
			);
		}

		// There's some more query processing that has to happen here: search, other tax_query-based mappings, etc.

		$products = new WP_Query( $wp_query_args );
		$return = array_map( 'wc_get_product', $products->posts );
	}

	// . . .
}