Cart Price Rules

Cart Price Rule Model

// Magento\SalesRule\Model\Rule
namespace Magento\SalesRule\Model;

class Rule extends \Magento\Framework\DataObject implements
    \Magento\SalesRule\Api\Data\RuleInterface
{
    /**
     * Get rule data
     */
    public function getName(): string
    {
        return $this->getData('name');
    }

    public function getDiscountAmount(): float
    {
        return (float) $this->getData('discount_amount');
    }

    public function getCouponCode(): ?string
    {
        return $this->getData('coupon_code');
    }

    public function getFromDate(): ?string
    {
        return $this->getData('from_date');
    }

    public function getToDate(): ?string
    {
        return $this->getData('to_date');
    }
}

Rule Types

Coupon Generation

namespace Vendor\Promotion\Service;

class CouponManager
{
    public function __construct(
        private \Magento\SalesRule\Model\RuleFactory $ruleFactory,
        private \Magento\SalesRule\Model\CouponFactory $couponFactory
    ) {}

    public function generateCoupons(
        int $ruleId,
        int $quantity,
        string $format = 'alphanumeric'
    ): array {
        $rule = $this->ruleFactory->create()->load($ruleId);

        $codes = [];
        for ($i = 0; $i < $quantity; $i++) {
            $code = $this->generateCode($format);

            $coupon = $this->couponFactory->create();
            $coupon->setRuleId($ruleId);
            $coupon->setCode($code);
            $coupon->setUsageLimit(1);
            $coupon->save();

            $codes[] = $code;
        }

        return $codes;
    }

    private function generateCode(string $format): string
    {
        $length = 8;
        $characters = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';
        $code = '';
        for ($i = 0; $i < $length; $i++) {
            $code .= $characters[random_int(0, strlen($characters) - 1)];
        }
        return $code;
    }
}

Applying Coupons

// Apply coupon to quote
$quote->setCouponCode('SAVE10');
$quote->collectTotals()->save();

// Remove coupon
$quote->setCouponCode(null);
$quote->collectTotals()->save();

// Check if coupon is valid
$coupon = $this->couponFactory->create()->loadByCode('SAVE10');
if ($coupon->getId() && $coupon->isUsed()) {
    // Coupon is valid and can be used
}

Rule Conditions

// Cart price rule conditions
$rule->setConditionsSerialized(json_encode([
    'type' => 'Magento\SalesRule\Model\Rule\Condition\Combine',
    'attribute' => null,
    'operator' => null,
    'aggregator' => 'all',
    'value' => '1',
    'is_value_processed' => null,
    'new_child' => [
        [
            'type' => 'Magento\SalesRule\Model\Rule\Condition\Product',
            'attribute' => 'qty',
            'operator' => '>=',
            'value' => '3',
        ],
        [
            'type' => 'Magento\SalesRule\Model\Rule\Condition\Product',
            'attribute' => 'category_ids',
            'operator' => '()',
            'value' => [4, 5],
        ],
    ],
]));

Rule Actions

// Discount action types
$rule->setSimpleAction('by_percent'); // Percentage discount
$rule->setSimpleAction('by_fixed');   // Fixed amount discount
$rule->setSimpleAction('cart_fixed');  // Fixed amount for whole cart
$rule->setSimpleAction('buy_x_get_y'); // Buy X get Y free

// Set discount amount
$rule->setDiscountAmount(10); // 10% or $10 depending on action

// Apply to shipping
$rule->setApplyToShipping(true);

// Stop further rules processing
$rule->setStopRulesProcessing(true);

Example: Buy 3 Get 10% Off

$rule = $this->ruleFactory->create();
$rule->setName('Buy 3 Get 10% Off');
$rule->setIsActive(1);
$rule->setWebsiteIds([1]);
$rule->setCustomerGroupIds([0, 1, 2, 3]);
$rule->setSimpleAction('by_percent');
$rule->setDiscountAmount(10);
$rule->setCouponType(1); // 1 = specific coupons
$rule->setUsesPerCoupon(1);
$rule->setUsesPerCustomer(1);

// Condition: qty >= 3
$rule->setConditionsSerialized(json_encode([
    'type' => 'Magento\SalesRule\Model\Rule\Condition\Product',
    'attribute' => 'qty',
    'operator' => '>=',
    'value' => '3',
]));

$rule->save();

Catalog vs Cart Rules

// Catalog Price Rules - applied to product prices before add to cart
// Affects product listing and detail page prices

// Cart Price Rules - applied during checkout
// Affects cart totals and final price

Catalog Rule Model

namespace Magento\CatalogRule\Model;

class Rule extends \Magento\Rule\Model\AbstractModel
{
    public function getName(): string
    {
        return $this->getData('name');
    }

    public function getDiscountAmount(): float
    {
        return (float) $this->getData('discount_amount');
    }

    public function getFromDate(): ?string
    {
        return $this->getData('from_date');
    }

    public function getToDate(): ?string
    {
        return $this->getData('to_date');
    }
}

Catalog Rule Application

// Catalog rules are applied via cron or manual run
// Products get their prices updated in catalog_product_index_price

// Check catalog rule discount
$catalogRulePrice = $this->catalogRule->calcRulePrice(
    $productId,
    $websiteId,
    $customerGroupId
);

// Product displays discounted price
$product->setPrice($catalogRulePrice);