Applying Enterprise Application Design Patterns on Force.com

Andrew Fawcett, FinancialForce.com, CTO

@andyinthecloud

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All about FinancialForce.com

• #1 Accounting App on Force.com• #1 Professional Services Automation App on Force.com

Leading Native ISV on Force.com

• UNIT4 - $600 million, 33 years building business apps

Backed by Salesforce.com & UNIT4

• San Francisco HQ – 595 Market St.• 145 Employees• Customers in 23 countries

Growing Rapidly

Andrew Fawcett

CTO

@andyinthecloud

What are Enterprise Design Patterns?

Recipes for Engineers

Key Patterns Separation of Concerns (SOC)

Data Mapper

Domain Model

Services

Unit of Work

Reference Martin Fowler http://martinfowler.com/eaaCatalog/

Author of “Patterns of Enterprise

Application Architecture”

NOTE: Some additional care is required

to select and apply to Apex and Force.com

Agenda and sample code overview

“Opportunity Extensions” Package Required Features

• Ability to Discount an Opportunity easily

• Ability to create Invoices from an Opportunity

• Quick Opportunity Wizard from Account and

MRU Products

Agenda : Code walk throughs… Review code sets to compare,

discuss and contrast

Sample A is implemented without

considering patterns…

/** * Version: v1 * Visualforce Controller accepts a discount value * from the user and applies it to the Opportunity */

01: public PageReference applyDiscount()02: {03: try04: {05: // Query Opportunity and line items to apply discount to06: Opportunity opportunity = 07: [select Id, Name, (select UnitPrice from OpportunityLineItems) 08: from Opportunity o 09: where Id = :standardController.getId()]; 10: // Apply discount to line items11: Util.applyDiscount(opportunity, DiscountPercentage);12: }13: catch (Exception e)14: {15: ApexPages.addMessages(e);16: }17: return null;18: }

01: // Calculate discount factor02: Decimal factor = Util.calculateFactor(discountPercentage);03: if(opportunity.OpportunityLineItems.size()==0)04: {05: // Adjust the Amount on the Opportunity if no lines06: opportunity.Amount = opportunity.Amount * factor;07: update opportunity;08: }09: else10: {11: // Adjust UnitPrice of each line12: for(OpportunityLineItem line : opportunity.OpportunityLineItems)13: line.UnitPrice = line.UnitPrice * factor;14: update opportunity.OpportunityLineItems;15: }

Sample A: Apply Discount @ v1

/** * Version: v1 * Developer has reused Util.applyDiscount to combine as a convenience for the user the two * tasks into one. But what would be the state of the Opportunity if Util.createInvoice threw * an exception? */

01: public PageReference createInvoice()02: {03: try {04: // Query Opportunity and line items to apply discount to05: Opportunity opportunity = 06: [select Id, Name, AccountId, (select UnitPrice, Description, Quantity from OpportunityLineItems) 07: from Opportunity o 08: where Id = :standardController.getId()]; 09: // Apply discount to line items10: Util.applyDiscount(opportunity, DiscountPercentage);11: // Create Invoice from line items12: Id invoiceId = Util.createInvoice(opportunity);13: // Redirect to Invoice 14: return new PageReference('/'+invoiceId);15: }16: catch (Exception e) {17: ApexPages.addMessages(e);18: }

Transaction issue!Opportunity line changes are

not rolled back on Invoice creation failure. Automatic

rollback only occurs for unhandled exceptions.

Sample A: Create Invoice @ v1

/** * Version: v2 * Developer has implemented an enhancement to apply discounts conditionally per line based on the * two new fields Opportunity.DiscountType__c and Product.DiscoutingApproved__c */

01:public PageReference applyDiscount()02:{03: try04: {05: // Query Opportunity and line items to apply discount to06: // ENH:1024. Added new columns to support new features in applyDiscount07: Opportunity opportunity = 08: [select Id, Name, DiscountType__c, 09: (select UnitPrice, PricebookEntry.Product2.DiscountingApproved__c from OpportunityLineItems) 10: from Opportunity o 11: where Id = :standardController.getId()];12: // Apply discount to line items13: Util.applyDiscount(opportunity, DiscountPercentage);

01: // ENH:1024. Adjust UnitPrice of each line according to Discount Type of Opportunity02: for(OpportunityLineItem line : opportunity.OpportunityLineItems)03: {04: // ENH:1024. Skip products that have not been approved for discounting01:05: if(opportunity.DiscountType__c == 'Approved Products')06: if(line.PricebookEntry.Product2.DiscountingApproved__c == false)07: continue;08: // Adjust UnitPrice09: line.UnitPrice = line.UnitPrice * factor;10: }

Sample A: Apply Discount @ v2

/** * Version: v2 * NOTE: This code has not been changed since v1. What error occurs when Util.applyDiscount is * executed given the changes in v2 on the slide before? */01: public PageReference createInvoice()02: {03: try04: {05: // Query Opportunity and line items to apply discount to06: Opportunity opportunity = 07: [select Id, Name, AccountId,08: (select UnitPrice, Description, Quantity from OpportunityLineItems) 09: from Opportunity o 10: where Id = :standardController.getId()]; 11: // Apply discount to line items12: Util.applyDiscount(opportunity, DiscountPercentage);13: // Create Invoice from line items14: Id invoiceId = Util.createInvoice(opportunity);15: // Redirect to Invoice 16: return n17: }

Sample A: Create Invoice @ v2

/** * A Opportunity Wizard that displays the most recently used Products and allows the user to * select them to create an new Opportunity. Is there any logic here that does not belong? */

01: public QuickOpportunityWizardController(ApexPages.StandardController controller)02: {03: standardController = controller;04: 05: // Create a new Opportunity defaulting from the Account06: Account account = (Account) standardController.getRecord();07: viewState = new ViewState();08: viewState.Opportunity = new Opportunity();09: viewState.Opportunity.Name = account.Name; 10: viewState.Opportunity.AccountId = account.Id;11: viewState.Opportunity.DiscountType__c = OpportunitySettings__c.getInstance().DiscountType__c;12: viewState.SelectLineItemList = new List<SelectLineItem>();13: 14: // Recently used Opportunity lines15: List<OpportunityLineItem> lines = In order to ensure consistent

behavior, across this wizard, Salesforce UI and API’s, this logic needs to be placed in a trigger

Sample A: Opportunity Wizard

Issues Discussed• Partial database updates in error conditions• Data dependent runtime errors• Inconsistent behavior between UI’s, API’s and Tools

Other Concerns• Code not factored for exposure via an Application API

• Business functionality implemented in controller classes

• Util methods are not bulkified, causing callers to inhert bulkification issues• CRUD security not enforced

Sample A: Create Invoice @ v2

Sample B: Class Diagram

/** * Controller methods interact and call only the * Service class methods. There is no transaction * management needed in the controller methods. However * error handling and reporting is managed by controller. */

01: public PageReference applyDiscount()02: {03: try04: {05: // Apply discount entered to the current Opportunity06: OpportunitiesService.applyDiscounts(07: new List<ID> { standardController.getId() }, DiscountPercentage);08: }09: catch (Exception e)10: {11: ApexPages.addMessages(e);12: }13: return null;14: }

01: public PageReference createInvoice()02: {03: try04: {05: // Create Invoice from line items of the current Opportunity06: List<ID> invoiceIds = 07: OpportunitiesService.createInvoices(08: new List<ID> { standardController.getId() }, DiscountPercentage);09: 10: // Redirect to Invoice 11: return new PageReference('/'+invoiceIds[0]);12: 13: }14: catch (Exception e)15: {16: ApexPages.addMessages(e);17: }18: return null;19: }

01: public PageReference createOpportunity()02: {03: try04: {05: // Create Opportunity from line items selected by the user06: List<ID> opportunityIds = 07: OpportunitiesService.createOpportunities(08: new List<ID> { standardController.getId() }, selectedLines);09: 10: // Redirect to Opportunity11: return new PageReference('/'+opportunity[0]);12: 13: }14: catch (Exception e)15: {16: ApexPages.addMessages(e);17: }18: return null;19: }

Sample B: Controller Methods

/** * Service methods are the main entry point for your applications * logic. Your controller methods call these. In addition they can * form a public API for partners and developers using your * application. Service methods utilize code from Domain, Selector * and Unit Of Work classes. */01: global with sharing class OpportunitiesService 02: {03: global static void applyDiscounts(Set<ID> opportunityIds, Decimal discountPercentage)04: {05: // Create unit of work to capture work and commit it under one transaction06: SObjectUnitOfWork uow = new SObjectUnitOfWork(SERVICE_SOBJECTS);07: // Query Opportunities (including products) and apply discount08: Opportunities opportunities = new Opportunities(09: new OpportunitiesSelector().selectByIdWithProducts(opportunityIds));10: opportunities.applyDiscount(discountPercentage, uow);11: // Commit updates to opportunities12: uow.commitWork();13: }14: 15: // SObject's used by the logic in this service, listed in dependency order16: private static List<Schema.SObjectType> SERVICE_SOBJECTS = 17: new Schema.SObjectType[] { 18: Invoice__c.SObjectType, 19: Opportunity.SObjectType, 20: OpportunityLineItem.SObjectType };

Sample B: Service and Unit Of Work

/** * This service method passes its Unit Of Work to a related domain * class such that it can also register any database changes. * See Opportunities.applyDiscount method. */

01: global static List<Id> createInvoices(Set<ID> opportunityIds, Decimal discountPercentage)02: {03: // Create unit of work to capture work and commit it under one transaction04: SObjectUnitOfWork unitOfWork = new SObjectUnitOfWork(SERVICE_SOBJECTS);05: // Query Opportunities06: Opportunities opportunities = new Opportunities(07: new OpportunitiesSelector().selectByIdWithProducts(opportunityIds));08: // Optionally apply discounts as part of invoice creation09: if(discountPercentage!=null && discountPercentage>0)10: opportunities.applyDiscount(discountPercentage, unitOfWork);11: // Create Invoices from the given opportunities12: List<Invoice__c> invoices = new List<Invoice__c>();13: for(Opportunity opportunityRecord : (List<Opportunity>) opportunities.Records)14: {15: // Create Invoice and populate invoice fields (removed here) from Opportunity ...16: Invoice__c invoice = new Invoice__c();17: unitOfWork.registerNew(invoice);18: }19: // Commit any Opportunity updates and new Invoices20: unitOfWork.commitWork();

Sample B: Service and Unit Of Work

Sample B: Unit of Work : Commit Work01: public with sharing class SObjectUnitOfWork02: {03: public void commitWork()04: {05: // Wrap the work in its own transaction 06: Savepoint sp = Database.setSavePoint();07: try08: {09: // Insert by type10: for(Schema.SObjectType sObjectType : m_sObjectTypes)11: {12: m_relationships.get(sObjectType.getDescribe().getName()).resolve();13: insert m_newListByType.get(sObjectType.getDescribe().getName());14: }15:: // Update by type16: for(Schema.SObjectType sObjectType : m_sObjectTypes)17: update m_dirtyListByType.get(sObjectType.getDescribe().getName());18: // Delete by type (in reverse dependency order)19: Integer objectIdx = m_sObjectTypes.size() - 1;20: while(objectIdx>=0)21: delete m_deletedListByType.get(m_sObjectTypes[objectIdx--].getDescribe().getName());22: }23: catch (Exception e)24: {25: // Rollback26: Database.rollback(sp);27: // Throw exception on to caller28: throw e;29: }30: }31: }

/** * These classes manage in a single place all queries to a given object. Maintaining a single list of * fields that will be queried. The base class SObjectSelector provides selectSObjectById method for free! * NOTE: This base class also handles CRUD security. */

01: public with sharing class OpportunitiesSelector extends SObjectSelector02: {03: public List<Schema.SObjectField> getSObjectFieldList()04: {05: return new List<Schema.SObjectField> {06: Opportunity.AccountId, Opportunity.Amount, Opportunity.CloseDate, Opportunity.Description,07: Opportunity.ExpectedRevenue, Opportunity.Id, Opportunity.Name, Opportunity.Pricebook2Id, 08: Opportunity.Probability, Opportunity.StageName, Opportunity.Type, Opportunity.DiscountType__c09: };10: }11: public Schema.SObjectType getSObjectType()12: {13: return Opportunity.sObjectType;14: }15: public List<Opportunity> selectById(Set<ID> idSet)16: {17: return (List<Opportunity>) selectSObjectsById(idSet);18: }19: }

Sample B: Data Mapper : Simple

/** * This additional Selector method illustrates how other selectors can be consumed to ensure that * field lists from other objects queried via a parent object query are also consistently applied. * NOTE: The SObjectSelector logic is also multi-company aware, injecting CurrencyIsoCode as needed. */

01: public List<Opportunity> selectByIdWithProducts(Set<ID> idSet)02: {03: /** Omitted for brevity: Construction of dependent selectors */04: 05: String query = String.format(06: 'select {0}, 07: (select {3},{5},{6},{7} from OpportunityLineItems order by {4}) ' + 08: 'from {1} where id in :idSet order by {2}', 09: new List<String> {10: getFieldListString(), getSObjectName(), getOrderBy(),11: opportunityLineItemSelector.getFieldListString(),12: opportunityLineItemSelector.getOrderBy(),13: pricebookEntrySelector.getRelatedFieldListString('PricebookEntry'),14: productSelector.getRelatedFieldListString('PricebookEntry.Product2'),15: pricebookSelector.getRelatedFieldListString('PricebookEntry.Pricebook2’) });16: 17: return (List<Opportunity>) Database.query(query);18: }

Sample B: Data Mapper : Complex

/** * Implement the Apex Trigger by calling the SObjectDomain method triggerHandler, which routes to the * appropriate methods implemented in the domain class. Such as applyDefaults() during * record inserts. Other methods are validate(), beforeInsert (), afterInsert() etc.. */

01: trigger OpportunitiesTrigger on Opportunity 02: (after delete, after insert, after update, before delete, before insert, before update) 03: {04: // Creates Domain class instance and calls appropriate override methods according to Trigger state05: SObjectDomain.triggerHandler(Opportunities.class);06: }

Sample B: Domain Model : Trigger and Domain Class

01: public with sharing class Opportunities extends SObjectDomain02: {03: public Opportunities(List<Opportunity> sObjectList)04: {05: super(sObjectList); // Classes are initialized with lists to enforce bulkification throughout06: }07: 08: public override void applyDefaults()09: {10: for(Opportunity opportunity : (List<Opportunity>) Records) // Apply defaults to Opportunities11: {12: opportunity.DiscountType__c = OpportunitySettings__c.getInstance().DiscountType__c;13: }14: }15: }

/** * Domain class method implements * the discount logic, note * bulkification is enforced here. * Unit of Work for database * updates. While delegating to * the domain class responsible * for Opportunity Products to * apply discounts as needed to * product lines. */

01: public void applyDiscount(Decimal discountPercentage, SObjectUnitOfWork unitOfWork)02: {03: // Calculate discount factor04: Decimal factor = Util.calculateDiscountFactor(discountPercentage);05: // Opportunity lines to apply discount to06: List<OpportunityLineItem> linesToApplyDiscount = new List<OpportunityLineItem>();07: // Apply discount 08: for(Opportunity opportunity : (List<Opportunity>) Records)09: {10: // Apply to the Opportunity Amount?11: if(opportunity.OpportunityLineItems.size()==0)12: {13: // Adjust the Amount on the Opportunity if no lines14: opportunity.Amount = opportunity.Amount * factor;15: unitOfWork.registerDirty(opportunity);16: }17: else18: {19: // Collect lines to apply discount to20: linesToApplyDiscount.add(opportunity.OpportunityLineItems);21: }22: }23: // Apply discount to lines24: OpportunityLineItems lineItems = new OpportunityLineItems(linesToApplyDiscount);25: lineItems.applyDiscount(discountPercentage, unitOfWork);26: }

Sample B: Domain Model : Business Logic

Separation of Concern Pattern. Code is factored in respect to its purpose and responsibility and thus easier to maintain and behaves consistently.Service Pattern, task and process based logic is exposed consistently from a single place and consumed by all ‘clients’. Controllers and external callers.Data Mapper, the selector classes provide a single place to query objects and enforce CRUD security.Unit Of Work Pattern provides a single transactional context via the commitWork method. Bulkification of DML operations is simplified via registerXXX methods. Domain Pattern, provides object orientated model for defaulting, validation and behavioral logic. Since domain classes manage record sets, they also enforce bulkfication throughout your logic not just in triggers. Trigger implementations can be standardized.

Summary

Java Code : {SourceObject__c} ListenerResources• Other // TODO:’s and Ideas?!

Review SObjectUnitOfWork further, it also aids in inserting related records and updating references!!

Auto handle CRUD security in SObjectDomain base class trigger delegate methods?

• Source Code and Contact DetailsGitHub: https://github.com/financialforcedev

Twitter: andyinthecloud