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bojanzbojanz
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Issue #2981526 by bojanz: Percentage order offers should make sure that the per-item discounts add up to the expected subtotal one
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6 files changed

Lines changed: 336 additions & 14 deletions

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‎modules/order/commerce_order.services.yml‎

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@@ -67,6 +67,10 @@ services:
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tags:
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- { name: commerce_store.store_resolver, priority: 100 }
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commerce_order.price_splitter:
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class: Drupal\commerce_order\PriceSplitter
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arguments: ['@entity_type.manager', '@commerce_price.rounder']
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commerce_order.price_calculator:
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class: Drupal\commerce_order\PriceCalculator
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arguments: ['@commerce_order.adjustment_transformer', '@commerce_order.chain_order_type_resolver', '@commerce_price.chain_price_resolver', '@entity_type.manager', '@request_stack']

‎modules/order/src/PriceSplitter.php‎

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<?php
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namespace Drupal\commerce_order;
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use Drupal\commerce_order\Entity\OrderInterface;
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use Drupal\commerce_price\Calculator;
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use Drupal\commerce_price\Price;
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use Drupal\commerce_price\RounderInterface;
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use Drupal\Core\Entity\EntityTypeManagerInterface;
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class PriceSplitter implements PriceSplitterInterface {
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/**
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* The currency storage.
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*
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* @var \Drupal\Core\Entity\EntityStorageInterface
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*/
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protected $currencyStorage;
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/**
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* The rounder.
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*
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* @var \Drupal\commerce_price\RounderInterface
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*/
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protected $rounder;
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/**
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* Constructs a new PriceSplitter object.
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*
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* @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
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* The entity type manager.
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* @param \Drupal\commerce_price\RounderInterface $rounder
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* The rounder.
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*/
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public function __construct(EntityTypeManagerInterface $entity_type_manager, RounderInterface $rounder) {
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$this->currencyStorage = $entity_type_manager->getStorage('commerce_currency');
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$this->rounder = $rounder;
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}
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/**
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* {@inheritdoc}
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*/
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public function split(OrderInterface $order, Price $amount, $percentage = NULL) {
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if (!$percentage) {
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// The percentage is intentionally not rounded, for maximum precision.
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$percentage = Calculator::divide($amount->getNumber(), $order->getSubtotalPrice()->getNumber());
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}
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// Calculate the initial per-order-item amounts using the percentage.
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// Round down to ensure that their sum isn't larger than the full amount.
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$amounts = [];
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foreach ($order->getItems() as $order_item) {
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if (!$order_item->getTotalPrice()->isZero()) {
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$individual_amount = $order_item->getTotalPrice()->multiply($percentage);
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$individual_amount = $this->rounder->round($individual_amount, PHP_ROUND_HALF_DOWN);
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$amounts[$order_item->id()] = $individual_amount;
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$amount = $amount->subtract($individual_amount);
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}
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}
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// The individual amounts don't add up to the full amount, distribute
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// the reminder among them.
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if (!$amount->isZero()) {
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/** @var \Drupal\commerce_price\Entity\CurrencyInterface $currency */
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$currency = $this->currencyStorage->load($amount->getCurrencyCode());
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$precision = $currency->getFractionDigits();
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// Use the smallest rounded currency amount (e.g. '0.01' for USD).
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$smallest_number = Calculator::divide('1', pow(10, $precision), $precision);
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$smallest_amount = new Price($smallest_number, $amount->getCurrencyCode());
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while (!$amount->isZero()) {
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foreach ($amounts as $order_item_id => $individual_amount) {
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$amounts[$order_item_id] = $individual_amount->add($smallest_amount);
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$amount = $amount->subtract($smallest_amount);
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if ($amount->isZero()) {
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break 2;
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}
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}
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}
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}
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return $amounts;
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}
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}

‎modules/order/src/PriceSplitterInterface.php‎

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<?php
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namespace Drupal\commerce_order;
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use Drupal\commerce_order\Entity\OrderInterface;
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use Drupal\commerce_price\Price;
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/**
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* Splits price amounts across order items.
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*
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* Useful for dividing a single order-level promotion or fee into multiple
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* order-item-level ones, for easier VAT calculation or refunds.
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*/
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interface PriceSplitterInterface {
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/**
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* Splits the given amount across order items.
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*
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* @param \Drupal\commerce_order\Entity\OrderInterface $order
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* The order.
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* @param \Drupal\commerce_price\Price $amount
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* The amount.
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* @param string $percentage
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* The percentage used to calculate the amount, as a decimal.
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* For example, '0.2' for 20%. When missing, calculated by comparing
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* the amount to the order subtotal.
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*
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* @return \Drupal\commerce_price\Price[]
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* An array of amounts keyed by order item ID.
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*/
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public function split(OrderInterface $order, Price $amount, $percentage = NULL);
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}

‎modules/order/tests/src/Kernel/PriceSplitterTest.php‎

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<?php
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namespace Drupal\Tests\commerce_order\Kernel;
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use Drupal\commerce_order\Entity\Order;
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use Drupal\commerce_order\Entity\OrderItem;
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use Drupal\commerce_order\Entity\OrderItemType;
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use Drupal\commerce_price\Price;
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use Drupal\Tests\commerce\Kernel\CommerceKernelTestBase;
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/**
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* Tests the price splitter.
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*
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* @coversDefaultClass \Drupal\commerce_order\PriceSplitter
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*
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* @group commerce
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*/
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class PriceSplitterTest extends CommerceKernelTestBase {
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/**
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* A sample order.
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*
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* @var \Drupal\commerce_order\Entity\OrderInterface
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*/
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protected $order;
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/**
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* The price splitter.
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*
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* @var \Drupal\commerce_order\PriceSplitterInterface
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*/
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protected $splitter;
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/**
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* Modules to enable.
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*
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* @var array
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*/
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public static $modules = [
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'entity_reference_revisions',
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'path',
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'profile',
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'state_machine',
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'commerce_product',
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'commerce_order',
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];
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/**
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* {@inheritdoc}
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*/
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protected function setUp() {
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parent::setUp();
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$this->installEntitySchema('profile');
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$this->installEntitySchema('commerce_order');
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$this->installEntitySchema('commerce_order_item');
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$this->installEntitySchema('commerce_product');
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$this->installEntitySchema('commerce_product_variation');
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$this->installConfig(['commerce_product', 'commerce_order']);
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$user = $this->createUser(['mail' => $this->randomString() . '@example.com']);
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OrderItemType::create([
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'id' => 'test',
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'label' => 'Test',
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'orderType' => 'default',
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])->save();
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$order = Order::create([
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'type' => 'default',
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'state' => 'draft',
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'mail' => $user->getEmail(),
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'uid' => $user->id(),
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'ip_address' => '127.0.0.1',
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'order_number' => '6',
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'store_id' => $this->store->id(),
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]);
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$order->save();
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$this->order = $this->reloadEntity($order);
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$this->splitter = $this->container->get('commerce_order.price_splitter');
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}
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/**
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* @covers ::split
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*/
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public function testSplit() {
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// 6 x 3 + 6 x 3 = 36.
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$amount = new Price('6', 'USD');
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$order_items = $this->buildOrderItems([$amount, $amount]);
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$this->order->setItems($order_items);
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$this->order->save();
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// Each order item should be discounted by half (9 USD).
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$amounts = $this->splitter->split($this->order, new Price('18', 'USD'));
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$expected_amount = new Price('9', 'USD');
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$this->assertEquals([$expected_amount, $expected_amount], array_values($amounts));
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// Same result with an explicit percentage.
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$amounts = $this->splitter->split($this->order, new Price('18', 'USD'), '0.5');
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$expected_amount = new Price('9', 'USD');
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$this->assertEquals([$expected_amount, $expected_amount], array_values($amounts));
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// 9.99 x 3 + 1.01 x 3 = 33.
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$first_amount = new Price('9.99', 'USD');
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$second_amount = new Price('1.01', 'USD');
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$order_items = $this->buildOrderItems([$first_amount, $second_amount]);
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$this->order->setItems($order_items);
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$this->order->save();
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$amount = new Price('5', 'USD');
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$amounts = $this->splitter->split($this->order, $amount);
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$first_expected_amount = new Price('4.54', 'USD');
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$second_expected_amount = new Price('0.46', 'USD');
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$this->assertEquals($amount, $first_expected_amount->add($second_expected_amount));
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$this->assertEquals([$first_expected_amount, $second_expected_amount], array_values($amounts));
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// Split an amount that has a reminder.
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$amount = new Price('3.98', 'USD');
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$amounts = $this->splitter->split($this->order, $amount);
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$first_expected_amount = new Price('3.62', 'USD');
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$second_expected_amount = new Price('0.36', 'USD');
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$this->assertEquals($amount, $first_expected_amount->add($second_expected_amount));
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$this->assertEquals([$first_expected_amount, $second_expected_amount], array_values($amounts));
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}
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/**
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* Builds the order items for the given unit prices.
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*
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* @param \Drupal\commerce_price\Price[] $unit_prices
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* The unit prices.
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*
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* @return \Drupal\commerce_order\Entity\OrderItemInterface[]
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* The order items.
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*/
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protected function buildOrderItems(array $unit_prices) {
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$order_items = [];
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foreach ($unit_prices as $unit_price) {
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$order_item = OrderItem::create([
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'type' => 'test',
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'unit_price' => $unit_price,
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'quantity' => '3',
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]);
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$order_item->save();
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$order_items[] = $order_item;
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}
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return $order_items;
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}
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}

‎modules/promotion/src/Plugin/Commerce/PromotionOffer/OrderPercentageOff.php‎

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@@ -3,12 +3,17 @@
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namespace Drupal\commerce_promotion\Plugin\Commerce\PromotionOffer;
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55
use Drupal\commerce_order\Adjustment;
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use Drupal\commerce_order\PriceSplitterInterface;
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use Drupal\commerce_price\RounderInterface;
68
use Drupal\commerce_promotion\Entity\PromotionInterface;
79
use Drupal\Core\Entity\EntityInterface;
10+
use Symfony\Component\DependencyInjection\ContainerInterface;
811

912
/**
1013
* Provides the percentage off offer for orders.
1114
*
15+
* The discount is split between order items, to simplify VAT taxes and refunds.
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*
1217
* @CommercePromotionOffer(
1318
* id = "order_percentage_off",
1419
* label = @Translation("Percentage off the order subtotal"),
@@ -17,26 +22,70 @@
1722
*/
1823
class OrderPercentageOff extends PercentageOffBase {
1924

25+
/**
26+
* The price splitter.
27+
*
28+
* @var \Drupal\commerce_order\PriceSplitterInterface
29+
*/
30+
protected $splitter;
31+
32+
/**
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* Constructs a new OrderPercentageOff object.
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*
35+
* @param array $configuration
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* A configuration array containing information about the plugin instance.
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* @param string $plugin_id
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* The pluginId for the plugin instance.
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* @param mixed $plugin_definition
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* The plugin implementation definition.
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* @param \Drupal\commerce_price\RounderInterface $rounder
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* The rounder.
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* @param \Drupal\commerce_order\PriceSplitterInterface $splitter
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* The splitter.
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*/
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public function __construct(array $configuration, $plugin_id, $plugin_definition, RounderInterface $rounder, PriceSplitterInterface $splitter) {
47+
parent::__construct($configuration, $plugin_id, $plugin_definition, $rounder);
48+
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$this->splitter = $splitter;
50+
}
51+
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/**
53+
* {@inheritdoc}
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*/
55+
public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
56+
return new static(
57+
$configuration,
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$plugin_id,
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$plugin_definition,
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$container->get('commerce_price.rounder'),
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$container->get('commerce_order.price_splitter')
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);
63+
}
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2065
/**
2166
* {@inheritdoc}
2267
*/
2368
public function apply(EntityInterface $entity, PromotionInterface $promotion) {
2469
$this->assertEntity($entity);
2570
/** @var \Drupal\commerce_order\Entity\OrderInterface $order */
2671
$order = $entity;
27-
// Reduce each individual order item, to simplify VAT taxes, refunds.
72+
$percentage = $this->getPercentage();
73+
// Calculate the order-level discount and split it across order items.
74+
$amount = $order->getSubtotalPrice()->multiply($percentage);
75+
$amount = $this->rounder->round($amount);
76+
$amounts = $this->splitter->split($order, $amount, $percentage);
77+
2878
foreach ($order->getItems() as $order_item) {
29-
$adjustment_amount = $order_item->getTotalPrice()->multiply($this->getPercentage());
30-
$adjustment_amount = $this->rounder->round($adjustment_amount);
31-
32-
$order_item->addAdjustment(new Adjustment([
33-
'type' => 'promotion',
34-
// @todo Change to label from UI when added in #2770731.
35-
'label' => t('Discount'),
36-
'amount' => $adjustment_amount->multiply('-1'),
37-
'percentage' => $this->getPercentage(),
38-
'source_id' => $promotion->id(),
39-
]));
79+
if (isset($amounts[$order_item->id()])) {
80+
$order_item->addAdjustment(new Adjustment([
81+
'type' => 'promotion',
82+
// @todo Change to label from UI when added in #2770731.
83+
'label' => t('Discount'),
84+
'amount' => $amounts[$order_item->id()]->multiply('-1'),
85+
'percentage' => $percentage,
86+
'source_id' => $promotion->id(),
87+
]));
88+
}
4089
}
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}
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