pixelperfectat/magento2-module-amasty-affiliate-attribution-fix

Fixes Amasty Affiliate attribution loss when non-affiliate coupon codes are applied

dev-main 2026-02-10 18:13 UTC

Requires

• php: ^8.3
• magento/framework: ^103.0
• magento/module-catalog: ^104.0
• magento/module-sales-rule: ^101.0

Requires (Dev)

• phpunit/phpunit: ^10.0

MIT

README

Fixes affiliate attribution loss in Amasty Affiliate when a non-affiliate coupon code is applied alongside an affiliate cookie.

The Problem

When a customer arrives via an affiliate link, Amasty Affiliate sets a cookie (current_affiliate_account_code). During cart calculation, AffiliateQuoteResolver::resolveAffiliateAccount() uses this cookie to identify the affiliate.

However, the method uses a priority chain with a bug:

1. Check quote->getCouponCode() — if found, look it up in the affiliate coupon table
2. If the coupon is not an affiliate coupon → NoSuchEntityException → return null immediately
3. Only if no coupon code is present → read the cookie

When a customer enters a regular (non-affiliate) coupon, step 2 short-circuits and the affiliate cookie is never checked. This causes:

• Affiliate rules are no longer applied during cart calculation
• SalesOrderAfterPlaceObserver cannot find an affiliate account → no transaction → attribution lost

The Fix

1. Cookie Fallback (AffiliateQuoteResolverPlugin)

An after plugin on AffiliateQuoteResolver::resolveAffiliateAccount() that falls back to the cookie when the original method returns null but the cookie is present.

2. Max-of-Two Discount (DiscountMaxComparisonPlugin)

An after plugin on Magento\SalesRule\Model\Quote\Discount::collect() that prevents affiliate and coupon discounts from stacking. When both apply to the same item, only the larger discount is kept.

• Coupon-specific rules (requiring a coupon code) are compared against affiliate rules
• Non-coupon rules (auto/site-wide sales) are not affected — they always apply
• Per-item comparison using Magento's built-in per-rule discount breakdown

Installation

composer require pixelperfectat/magento2-module-amasty-affiliate-attribution-fix
bin/magento module:enable PixelPerfect_AmastyAffiliateAttributionFix
bin/magento setup:upgrade

Configuration

None required — the module works automatically once installed.

Discount Stacking Behaviour

Scenario	Result
Affiliate only	Full affiliate discount applied
Coupon only	Full coupon discount applied
Both, affiliate larger	Affiliate discount applied, coupon removed
Both, coupon larger	Coupon discount applied, affiliate removed
Both + auto rule	Max(affiliate, coupon) + auto rule

To control stacking per-rule via Magento's built-in mechanism, set stop_rules_processing on individual sales rules.

Compatibility

• PHP 8.3+
• Magento 2.4.x
• Amasty Affiliate 2.3.0+

Testing

vendor/bin/phpunit

Manual Verification

1. Click an affiliate link → verify cookie is set
2. Add items to cart
3. Apply a regular (non-affiliate) coupon code
4. Place order
5. Check amasty_affiliate_transaction table → affiliate transaction exists
6. Check Admin → Affiliate → Transactions → order appears with correct affiliate