// Enterprise Design Patterns Implementation // 1. SERVICE LAYER — Business logic orchestration public with sharing class OpportunityService { // Public API — called by triggers, LWC, REST, Batch public static void closeDeals(Set opportunityIds) { // Query via Selector List opps = OpportunitiesSelector.getByIds(opportunityIds); // Apply domain logic Opportunities domain = new Opportunities(opps); domain.validateForClose(); domain.calculateFinalAmounts(); // Register changes via Unit of Work fflib_ISObjectUnitOfWork uow = Application.UnitOfWork.newInstance(); for (Opportunity opp : opps) { opp.StageName = 'Closed Won'; opp.CloseDate = Date.today(); uow.registerDirty(opp); // Create follow-up task Task followUp = new Task( Subject = 'Post-close follow-up: ' + opp.Name, WhatId = opp.Id, OwnerId = opp.OwnerId, ActivityDate = Date.today().addDays(7) ); uow.registerNew(followUp); } uow.commitWork(); // Single DML commit } public static void applyDiscount(Set oppIds, Decimal discountPercent) { List opps = OpportunitiesSelector.getByIds(oppIds); Opportunities domain = new Opportunities(opps); domain.applyDiscount(discountPercent); update opps; } } // 2. DOMAIN LAYER — Object-specific business rules public class Opportunities { private List records; public Opportunities(List records) { this.records = records; } // Validation public void validateForClose() { for (Opportunity opp : records) { if (opp.Amount == null || opp.Amount <= 0) { opp.addError('Amount must be positive to close'); } if (opp.ContactId == null) { opp.addError('Primary Contact required to close'); } } } // Business calculation public void calculateFinalAmounts() { for (Opportunity opp : records) { if (opp.Discount_Percent__c != null) { opp.Amount = opp.Amount * (1 - opp.Discount_Percent__c / 100); } } } // Apply discount public void applyDiscount(Decimal percent) { for (Opportunity opp : records) { opp.Discount_Percent__c = percent; opp.Amount = opp.Amount * (1 - percent / 100); } } } // 3. SELECTOR LAYER — Query encapsulation public inherited sharing class OpportunitiesSelector { private static final List DEFAULT_FIELDS = new List{ 'Id', 'Name', 'StageName', 'Amount', 'CloseDate', 'AccountId', 'OwnerId', 'ContactId', 'Discount_Percent__c' }; public static List getByIds(Set ids) { return Database.query( 'SELECT ' + String.join(DEFAULT_FIELDS, ', ') + ' FROM Opportunity WHERE Id IN :ids' ); } public static List getByAccountIds(Set accountIds) { return Database.query( 'SELECT ' + String.join(DEFAULT_FIELDS, ', ') + ' FROM Opportunity WHERE AccountId IN :accountIds' + ' ORDER BY CloseDate DESC' ); } public static List getOpenByOwner(Id ownerId) { return Database.query( 'SELECT ' + String.join(DEFAULT_FIELDS, ', ') + ' FROM Opportunity WHERE OwnerId = :ownerId' + ' AND IsClosed = false ORDER BY CloseDate ASC' ); } } // 4. STRATEGY PATTERN — Swappable business logic public interface IPricingStrategy { Decimal calculatePrice(Opportunity opp); } public class StandardPricing implements IPricingStrategy { public Decimal calculatePrice(Opportunity opp) { return opp.Amount; // No discount } } public class EnterprisePricing implements IPricingStrategy { public Decimal calculatePrice(Opportunity opp) { Decimal discount = opp.Amount > 100000 ? 0.15 : 0.05; return opp.Amount * (1 - discount); } } public class PartnerPricing implements IPricingStrategy { public Decimal calculatePrice(Opportunity opp) { return opp.Amount * 0.70; // 30% partner discount } } // Usage public class PricingService { public static Decimal getPrice(Opportunity opp, String channel) { IPricingStrategy strategy; switch on channel { when 'Standard' { strategy = new StandardPricing(); } when 'Enterprise' { strategy = new EnterprisePricing(); } when 'Partner' { strategy = new PartnerPricing(); } when else { strategy = new StandardPricing(); } } return strategy.calculatePrice(opp); } } // 5. FACTORY PATTERN — Dynamic handler creation public class TriggerHandlerFactory { private static Map handlerRegistry = new Map{ Account.SObjectType => AccountTriggerHandler.class, Contact.SObjectType => ContactTriggerHandler.class, Opportunity.SObjectType => OpportunityTriggerHandler.class }; public static ITriggerHandler getHandler(Schema.SObjectType objType) { Type handlerType = handlerRegistry.get(objType); if (handlerType == null) { throw new TriggerException('No handler registered for: ' + objType); } return (ITriggerHandler) handlerType.newInstance(); } }

Phase 9: Design Patterns & Architecture

0 of 2 topics completed

Enterprise Design Patterns in Apex

Scalable Architecture & System Design

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