.. rst-class:: outdated

How are rules checked?
======================

.. danger::

   We're sorry but **this documentation section is outdated**. Please have that in mind when trying to use it.
   You can help us making documentation up to date via Sylius Github. Thank you!

Everything related to this subject is located in ``Sylius\Component\Promotion\Checker``.

Rule checkers
-------------

New rules can be created by implementing ``RuleCheckerInterface``. This interface provides the method ``isEligible`` which aims to determine if the promotion subject respects the current rule or not.

I told you before that ``SyliusPromotionBundle`` ships with 2 types of rules : cart quantity rule and item total rule.

Cart quantity rule is defined via the service ``sylius.promotion_rule_checker.cart_quantity`` which uses the class ``CartQuantityRuleChecker``. The method ``isEligible`` checks here if the promotion subject has the minimum quantity (method ``getPromotionSubjectItemCount()`` of ``PromotionSubjectInterface``) required by the rule.

Item total rule is defined via the service ``sylius.promotion_rule_checker.item_total`` which uses the class ``ItemTotalRuleChecker``. The method ``isEligible`` checks here if the promotion subject has the minimum amount (method ``getPromotionSubjectItemTotal()`` of ``PromotionSubjectInterface``) required by the rule.


The promotion eligibility checker service
-----------------------------------------

To be eligible to a promotion, a subject must :

1. respect all the rules related to the promotion
2. respect promotion dates if promotion is limited by time
3. respect promotions usages count if promotion has a limited number of usages
4. if a coupon is provided with this order, it must be valid and belong to this promotion

The service ``sylius.promotion_eligibility_checker`` checks all these constraints for you with the method ``isEligible()``  which returns ``true`` or ``false``. This service uses the class ``CompositePromotionEligibilityChecker``.