Add getChangedFields to triggerContext (#65)

dev-tools/update-dependencies

@@ -7,5 +7,5 @@ rm -Rf fflib-apex-common/
 git clone https://github.com/apex-enterprise-patterns/fflib-apex-mocks.git
 git clone https://github.com/apex-enterprise-patterns/fflib-apex-common.git
 
-sfdx force:source:deploy -p ./fflib-apex-mocks/sfdx-source
+sfdx project deploy start -c --source-dir ./fflib-apex-mocks/sfdx-source
-sfdx force:source:deploy -p ./fflib-apex-common/sfdx-source
+sfdx project deploy start -c --source-dir ./fflib-apex-common/sfdx-source

sfdx-source/apex-extensions/main/triggerHandler/classes/fflib_TriggerContext.cls

@@ -95,6 +95,41 @@ public virtual inherited sharing class fflib_TriggerContext
 		return triggerOperation;
 	}
 
+	public Set<String> getChangedFields()
+	{
+		Set<String> result = new Set<String>();
+		for (SObject newRecord : getRecords())
+		{
+			Id recordId = (Id) newRecord.get('Id');
+			if (getExistingRecords() == null || !getExistingRecords().containsKey(recordId)) continue;
+
+			SObject oldRecord = getExistingRecords().get(recordId);
+			Map<String, Object> oldValuesByFieldName = oldRecord.getPopulatedFieldsAsMap();
+			Map<String, Object> newValuesByFieldName = newRecord.getPopulatedFieldsAsMap();
+			Set<String> fieldNames = new Set<String>();
+			fieldNames.addAll(oldValuesByFieldName.keySet());
+			fieldNames.addAll(newValuesByFieldName.keySet());
+			for (String fieldName : fieldNames)
+			{
+				if (oldValuesByFieldName.containsKey(fieldName) == false
+						&& newValuesByFieldName.containsKey(fieldName) == false) continue;
+
+				if ((oldValuesByFieldName.containsKey(fieldName) == false
+						&& newValuesByFieldName.containsKey(fieldName))
+						||
+						(oldValuesByFieldName.containsKey(fieldName)
+								&& newValuesByFieldName.containsKey(fieldName) == false)
+						||
+						(oldValuesByFieldName.get(fieldName) != newValuesByFieldName.get(fieldName))
+				)
+				{
+					result.add(fieldName);
+				}
+			}
+		}
+		return result;
+	}
+
 	/**
      * Detects whether any values in context records have changed for given field as string
      * Returns list of SObject records that have changes in the specified fields

sfdx-source/apex-extensions/tests/classes/triggerHandler/fflib_TriggerHandlerTest.cls

@@ -137,7 +137,40 @@ private class fflib_TriggerHandlerTest
 		// THEN it should only return the changed records
 		Map<Id, SObject> resultMap = new Map<Id, SObject>(result);
 		System.Assert.areEqual(1, result.size());
-		System.Assert.istrue(resultMap.containsKey(idLuke));
+		System.Assert.isTrue(resultMap.containsKey(idLuke));
+	}
+
+	@IsTest
+	private static void itShouldReturnTheChangedFields()
+	{
+		// GIVEN a domain with old and changed records
+
+		Id idLuke = fflib_IDGenerator.generate(Account.SObjectType);
+		Id idHan = fflib_IDGenerator.generate(Account.SObjectType);
+		Id idLeia = fflib_IDGenerator.generate(Account.SObjectType);
+		List<Account> oldRecords = new List<Account>
+		{
+				new Account(Id = idLuke, Name = 'Luke', Description = 'Jedi'),
+				new Account(Id = idHan, Name = 'Han', Description = 'Pilot'),
+				new Account(Id = idLeia, Name = 'Leia')
+		};
+
+		List<Account> newRecords = oldRecords.deepClone(true, true, true);
+		newRecords.get(0).Name = 'Luke SkyWalker';
+		newRecords.get(0).Description = 'Jedi Master';
+		newRecords.get(1).Name = 'Han Solo';
+		newRecords.get(1).Description = null;
+
+		fflib_TriggerContext ctx = new fflib_TriggerContext(newRecords);
+		ctx.existingRecords = new Map<Id, SObject>(oldRecords);
+
+		// WHEN we create a domain with ExistingRecords and request the changed records
+		Set<String> result = ctx.getChangedFields();
+
+		// THEN it should only return the changed records
+		System.Assert.areEqual(2, result.size());
+		System.Assert.isTrue(result.contains('Name'));
+		System.Assert.isTrue(result.contains('Description'));
 	}
 
 	@IsTest