woocommerce.get_or_create_attribute.php

<?php
namespace WooCommerce_Helpers {
	/**
	 * Looks for an existing WooCommerce attribute with the same label, or else
	 * creates a new attribute using the provided information.
	 *
	 * If a new attribute is successfully created, or an existing attribute is
	 * matched, the attribute object will be returned. Otherwise, bool false is
	 * returned.
	 *
	 * Note that when looking for existing attributes, the name is compared case
	 * insensitively ('license' matches 'License'). In the interests of avoiding
	 * confusion, it's also worth noting that the $label argument corresponds to
	 * the 'attribute_label' property in the returned attribute object, but to
	 * the 'name' argument in the context of a wc_create_attribute() call.
	 *
	 * @version WooCommerce 3.8.x
	 *
	 * @param string $label
	 * @param string $type
	 * @param string $orderby
	 * @param bool   $public
	 *
	 * @return object|false
	 */
	function get_or_create_attribute( string $label, string $type = 'select', $orderby = 'menu_order', bool $public = true ) {
		// Case insensitively match any existing attributes.
		foreach ( wc_get_attribute_taxonomies() as $attribute ) {
			if (
				property_exists( $attribute, 'attribute_label' )
				&& strtolower( $attribute->attribute_label ) === strtolower( $label )
			)  {
				return $attribute;
			}
		}

		// Otherwise, create a new attribute. Note that when we use wc_create_attribute(),
		// the 'name' argument corresponds to 'label' as returned by wc_get_attribute().
		$attribute_id = wc_create_attribute( [
			'name'    => $label,
			'type'    => $type,
			'orderby' => $orderby,
			'public'  => $public,
		] );

		return is_wp_error( $attribute_id ) ? false : wc_get_attribute( $attribute_id );
	}
}