Rebases the fix from PR apex-enterprise-patterns#137 against latest project structure and cleans up the couple of issues outlined on the prior PR comment thread (removes unused Exception and uses the SObjectType for the comparison vs. the String name)

Author: daveespo

sfdx-source/apex-common/main/classes/fflib_QueryFactory.cls

@@ -84,7 +84,7 @@ public class fflib_QueryFactory { //No explicit sharing declaration - inherit fr
 	private Schema.ChildRelationship relationship;
 	private Map<Schema.ChildRelationship, fflib_QueryFactory> subselectQueryMap;
 
-	private String getFieldPath(String fieldName){
+	private String getFieldPath(String fieldName, Schema.sObjectType relatedSObjectType){
 		if(!fieldName.contains('.')){ //single field
 			Schema.SObjectField token = fflib_SObjectDescribe.getDescribe(table).getField(fieldName.toLowerCase());
 			if(token == null)
@@ -107,8 +107,21 @@ public class fflib_QueryFactory { //No explicit sharing declaration - inherit fr
 				fflib_SecurityUtils.checkFieldIsReadable(lastSObjectType, token);
 			}
 
-			if(token != null && i.hasNext() && tokenDescribe.getSoapType() == Schema.SoapType.ID){
-				lastSObjectType = tokenDescribe.getReferenceTo()[0]; //if it's polymorphic doesn't matter which one we get
+			if (token != null && i.hasNext() && tokenDescribe.getSoapType() == Schema.SoapType.ID) {
+				List<Schema.sObjectType> relatedObjs = tokenDescribe.getReferenceTo(); //if it's polymorphic, it matters which one we use - i.e. Lead.Owner is GROUP|USER and each has different fields.
+
+				if (relatedObjs.size() == 1 || relatedSObjectType == null) {
+					lastSObjectType = relatedObjs[0]; //caller did not specify the one to use or there's only one so use the first one
+				}
+				else{
+					for (Schema.sObjectType sot : relatedObjs) {
+						if (fflib_SObjectDescribe.getDescribe(sot).getDescribe().getSObjectType() == relatedSObjectType) {
+							lastSObjectType = sot;
+							break;
+						}
+					}
+				}
+
 				fieldPath.add(tokenDescribe.getRelationshipName());
 			}else if(token != null && !i.hasNext()){
 				fieldPath.add(tokenDescribe.getName());
@@ -122,6 +135,10 @@ public class fflib_QueryFactory { //No explicit sharing declaration - inherit fr
 
 		return String.join(fieldPath,'.');
 	}
+	
+	private String getFieldPath(String fieldName) {
+		return this.getFieldPath(fieldName, null);
+	}
 
 	@TestVisible
 	private static String getFieldTokenPath(Schema.SObjectField field){
@@ -197,16 +214,27 @@ public class fflib_QueryFactory { //No explicit sharing declaration - inherit fr
 		this.sortSelectFields = doSort;
 		return this;
 	}
-	
 	/**
 	 * Selects a single field from the SObject specified in {@link #table}.
 	 * Selecting fields is idempotent, if this field is already selected calling this method will have no additional impact.
 	 * @param fieldName the API name of the field to add to the query's SELECT clause.
 	 **/
 	public fflib_QueryFactory selectField(String fieldName){ 		
-		fields.add( getFieldPath(fieldName) );
+		fields.add( getFieldPath(fieldName, null) );
+		return this;
+	}
+
+	/**
+		* Selects a single field from the SObject specified in {@link #table}.
+		* Selecting fields is idempotent, if this field is already selected calling this method will have no additional impact.
+		* @param fieldName the API name of the field to add to the query's SELECT clause.
+		* @param relatedSObjectType the related sObjectType to resolve polymorphic object fields.
+	 **/
+	public fflib_QueryFactory selectField(String fieldName, Schema.sOBjectType relatedObjectType) {
+		fields.add(getFieldPath(fieldName, relatedObjectType));
 		return this;
-	} 
+	}
+	
 	/**
 	 * Selects a field, avoiding the possible ambiguity of String API names.
 	 * @see #selectField(String)
@@ -760,6 +788,7 @@ public class fflib_QueryFactory { //No explicit sharing declaration - inherit fr
 			this.setMessage( 'Invalid field \''+fieldName+'\' for object \''+objectType+'\'' );
 		}
 	}
+
 	public class InvalidFieldSetException extends Exception{}
 	public class NonReferenceFieldException extends Exception{}
 	public class InvalidSubqueryRelationshipException extends Exception{}	

sfdx-source/apex-common/main/classes/fflib_SObjectSelector.cls

@@ -380,11 +380,13 @@ public abstract with sharing class fflib_SObjectSelector
      public void configureQueryFactoryFields(fflib_QueryFactory queryFactory, String relationshipFieldPath)
      {
 	// Add fields from selector prefixing the relationship path		
-	for(SObjectField field : getSObjectFieldList())		
-	queryFactory.selectField(relationshipFieldPath + '.' + field.getDescribe().getName());
-	// Automatically select the CurrencyIsoCode for MC orgs (unless the object is a known exception to the rule)
-        if(UserInfo.isMultiCurrencyOrganization() && CURRENCY_ISO_CODE_ENABLED)
-            queryFactory.selectField(relationshipFieldPath+'.CurrencyIsoCode');		
+		for(SObjectField field : getSObjectFieldList()) {
+			queryFactory.selectField(relationshipFieldPath + '.' + field.getDescribe().getName(), this.getSObjectType());
+		}
+		// Automatically select the CurrencyIsoCode for MC orgs (unless the object is a known exception to the rule)
+		if(UserInfo.isMultiCurrencyOrganization() && CURRENCY_ISO_CODE_ENABLED){
+			queryFactory.selectField(relationshipFieldPath+'.CurrencyIsoCode');
+		}
      }
 
     /**

sfdx-source/apex-common/test/classes/fflib_SObjectSelectorTest.cls

@@ -474,5 +474,85 @@ private with sharing class fflib_SObjectSelectorTest
 			return null;
 		}		
 		return testUser;
+	}
+
+	@isTest
+	static void testPolymorphicSelectWithRelatedType() {
+		//Given		
+
+		Testfflib_CampaignMemberSelector cmSelector = new Testfflib_CampaignMemberSelector();
+		fflib_QueryFactory qf = cmSelector.newQueryFactory();
+		new Testfflib_LeadSelector().configureQueryFactoryFields(qf, 'Lead');
+		new Testfflib_UserSelector().configureQueryFactoryFields(qf, 'Lead.Owner');
+
+
+		Set<String> expectedSelectFields = new Set<String>{
+				'Id', 'Status', 'Lead.Id', 'Lead.OwnerId', 'Lead.Owner.Id', 'Lead.Owner.UserRoleId'
+		};
+		if (UserInfo.isMultiCurrencyOrganization()) {
+			expectedSelectFields.add('CurrencyIsoCode');
+		}
+
+		//When
+		String soql = qf.toSOQL();
+
+		//Then
+		Pattern soqlPattern = Pattern.compile('SELECT (.*) FROM CampaignMember ORDER BY CreatedDate ASC NULLS FIRST ');
+		Matcher soqlMatcher = soqlPattern.matcher(soql);
+		soqlMatcher.matches();
+
+		List<String> actualSelectFields = soqlMatcher.group(1).deleteWhiteSpace().split(',');
+		System.assertEquals(expectedSelectFields, new Set<String>(actualSelectFields));
+	}
+
+	private class Testfflib_CampaignMemberSelector extends fflib_SObjectSelector {
+		public Testfflib_CampaignMemberSelector() {
+			super();
+		}
+
+		public List<Schema.SObjectField> getSObjectFieldList() {
+			return new List<Schema.SObjectField>{
+					CampaignMember.Id,
+					CampaignMember.Status
+			};
+		}
+
+		public Schema.SObjectType getSObjectType() {
+			return CampaignMember.sObjectType;
+		}
+	}
+
+	private class Testfflib_UserSelector extends fflib_SObjectSelector {
+		public Testfflib_UserSelector() {
+			super();
+		}
+
+		public List<Schema.SObjectField> getSObjectFieldList() {
+			return new List<Schema.SObjectField>{
+					User.UserRoleId,
+					User.Id
+			};
+		}
+
+		public Schema.SObjectType getSObjectType() {
+			return User.sObjectType;
+		}
+	}
+
+	private class Testfflib_LeadSelector extends fflib_SObjectSelector {
+		public Testfflib_LeadSelector() {
+			super();
+		}
+
+		public List<Schema.SObjectField> getSObjectFieldList() {
+			return new List<Schema.SObjectField>{
+					Lead.OwnerId,
+					Lead.Id
+			};
+		}
+
+		public Schema.SObjectType getSObjectType() {
+			return Lead.sObjectType;
+		}
 	}	
 }