LPD-37787 Filtering using r_<relationshipName>_c_<objectName>ERC is not working properly

modules/apps/object/object-rest-impl/src/main/java/com/liferay/object/rest/internal/odata/entity/ReferenceStringEntityField.java

@@ -0,0 +1,33 @@
+/**
+ * SPDX-FileCopyrightText: (c) 2025 Liferay, Inc. https://liferay.com
+ * SPDX-License-Identifier: LGPL-2.1-or-later OR LicenseRef-Liferay-DXP-EULA-2.0.0-2023-06
+ */
+
+package com.liferay.object.rest.internal.odata.entity;
+
+import com.liferay.portal.odata.entity.StringEntityField;
+
+import java.util.Locale;
+import java.util.function.Function;
+
+/**
+ * @author Carlos Correa
+ */
+public class ReferenceStringEntityField extends StringEntityField {
+
+	public ReferenceStringEntityField(
+		String fieldName, Function<Locale, String> filterableFunction,
+		String referenceFieldName) {
+
+		super(fieldName, locale -> referenceFieldName, filterableFunction);
+
+		_referenceFieldName = referenceFieldName;
+	}
+
+	public String getReferenceFieldName() {
+		return _referenceFieldName;
+	}
+
+	private final String _referenceFieldName;
+
+}

modules/apps/object/object-rest-impl/src/main/java/com/liferay/object/rest/internal/odata/entity/v1_0/ObjectEntryEntityModel.java

@@ -13,6 +13,7 @@
 import com.liferay.object.model.ObjectField;
 import com.liferay.object.model.ObjectRelationship;
 import com.liferay.object.relationship.util.ObjectRelationshipUtil;
+import com.liferay.object.rest.internal.odata.entity.ReferenceStringEntityField;
 import com.liferay.object.service.ObjectFieldLocalServiceUtil;
 import com.liferay.object.service.ObjectRelationshipLocalServiceUtil;
 import com.liferay.petra.string.StringPool;
@@ -33,9 +34,11 @@
 
 import java.util.HashMap;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Set;
+import java.util.function.Function;
 
 import javax.ws.rs.BadRequestException;
 
@@ -157,6 +160,10 @@ else if (Objects.equals(
 			"Unable to get entity field for object field " + objectField);
 	}
 
+	private Function<Locale, String> _getExternalReferenceCodeFunction() {
+		return locale -> "externalReferenceCode";
+	}
+
 	private Map<String, EntityField> _getObjectDefinitionEntityFieldsMap(
 		ObjectDefinition objectDefinition) {
 
@@ -211,7 +218,8 @@ private Map<String, EntityField> _getStringEntityFieldsMap(
 			).put(
 				"externalReferenceCode",
 				() -> new StringEntityField(
-					"externalReferenceCode", locale -> "externalReferenceCode")
+					"externalReferenceCode",
+					_getExternalReferenceCodeFunction())
 			).put(
 				"id", new IdEntityField("id", locale -> "id", String::valueOf)
 			).put(
@@ -279,9 +287,11 @@ private Map<String, EntityField> _getStringEntityFieldsMap(
 
 			entityFieldsMap.put(
 				objectRelationshipERCObjectFieldName,
-				new StringEntityField(
+				new ReferenceStringEntityField(
 					objectRelationshipERCObjectFieldName,
-					locale -> objectFieldName));
+					_getExternalReferenceCodeFunction(),
+					objectFieldName.split(StringPool.UNDERLINE)[1] +
+						"/externalReferenceCode"));
 
 			String relationshipIdName = objectFieldName.substring(
 				objectFieldName.lastIndexOf(StringPool.UNDERLINE) + 1);

modules/apps/object/object-rest-impl/src/main/java/com/liferay/object/rest/internal/odata/filter/expression/PredicateExpressionVisitorImpl.java

@@ -16,6 +16,7 @@
 import com.liferay.object.related.models.ObjectRelatedModelsPredicateProvider;
 import com.liferay.object.related.models.ObjectRelatedModelsPredicateProviderRegistry;
 import com.liferay.object.relationship.util.ObjectRelationshipUtil;
+import com.liferay.object.rest.internal.odata.entity.ReferenceStringEntityField;
 import com.liferay.object.rest.internal.util.BinaryExpressionConverterUtil;
 import com.liferay.object.rest.odata.entity.v1_0.provider.EntityModelProvider;
 import com.liferay.object.service.ObjectFieldLocalService;
@@ -161,6 +162,21 @@ public Object visitComplexPropertyExpression(
 				});
 		}
 
+		if (propertyExpression instanceof PrimitivePropertyExpression) {
+			PrimitivePropertyExpression primitivePropertyExpression =
+				(PrimitivePropertyExpression)propertyExpression;
+
+			Object value = _visitPrimitivePropertyExpression(
+				_getEntityField(
+					complexPropertyExpression.getName() + StringPool.SLASH +
+						primitivePropertyExpression.getName(),
+					_objectDefinition),
+				primitivePropertyExpression);
+
+			return complexPropertyExpression.getName() + StringPool.SLASH +
+				value;
+		}
+
 		return complexPropertyExpression.toString();
 	}
 
@@ -318,7 +334,10 @@ else if (type == MethodExpression.Type.STARTS_WITH) {
 	public Object visitPrimitivePropertyExpression(
 		PrimitivePropertyExpression primitivePropertyExpression) {
 
-		return primitivePropertyExpression.getName();
+		return _visitPrimitivePropertyExpression(
+			_getEntityField(
+				primitivePropertyExpression.getName(), _objectDefinition),
+			primitivePropertyExpression);
 	}
 
 	@Override
@@ -415,20 +434,32 @@ private ObjectRelationship _fetchObjectRelationship(
 	private Column<?, Object> _getColumn(
 		Object fieldName, ObjectDefinition objectDefinition) {
 
-		EntityField entityField = _getEntityField(fieldName, objectDefinition);
+		EntityField entityField = _getEntityField(
+			(String)fieldName, objectDefinition);
 
 		return (Column<?, Object>)_objectFieldLocalService.getColumn(
 			objectDefinition.getObjectDefinitionId(),
 			entityField.getFilterableName(null));
 	}
 
 	private EntityField _getEntityField(
-		Object fieldName, ObjectDefinition objectDefinition) {
+		String fieldName, ObjectDefinition objectDefinition) {
 
 		Map<String, EntityField> entityFieldsMap = _getEntityFieldsMap(
 			objectDefinition);
 
-		return entityFieldsMap.get(GetterUtil.getString(fieldName));
+		int index = fieldName.indexOf(StringPool.SLASH);
+
+		if (index == -1) {
+			return entityFieldsMap.get(fieldName);
+		}
+
+		return _getEntityField(
+			fieldName.substring(index + 1),
+			ObjectRelationshipUtil.getRelatedObjectDefinition(
+				objectDefinition,
+				_fetchObjectRelationship(
+					objectDefinition, fieldName.substring(0, index))));
 	}
 
 	private Map<String, EntityField> _getEntityFieldsMap(
@@ -645,7 +676,8 @@ else if (Objects.equals(BinaryExpression.Operation.OR, operation)) {
 	private Object _getValue(
 		Object left, ObjectDefinition objectDefinition, Object right) {
 
-		EntityField entityField = _getEntityField(left, objectDefinition);
+		EntityField entityField = _getEntityField(
+			(String)left, objectDefinition);
 
 		EntityField.Type entityType = entityField.getType();
 
@@ -696,7 +728,7 @@ private Object _getValue(
 
 		try {
 			ObjectField objectField = _objectFieldLocalService.getObjectField(
-				_objectDefinition.getObjectDefinitionId(),
+				objectDefinition.getObjectDefinitionId(),
 				entityFieldFilterableName);
 
 			ObjectFieldBusinessType objectFieldBusinessType =
@@ -760,6 +792,22 @@ else if (propertyExpression instanceof ComplexPropertyExpression) {
 				complexPropertyExpression.getPropertyExpression(),
 				relationshipsNames);
 		}
+		else if (propertyExpression instanceof PrimitivePropertyExpression) {
+			PrimitivePropertyExpression primitivePropertyExpression =
+				(PrimitivePropertyExpression)propertyExpression;
+
+			String relationshipsNamesString = StringUtil.merge(
+				relationshipsNames, StringPool.SLASH);
+
+			Object value = _visitPrimitivePropertyExpression(
+				_getEntityField(
+					relationshipsNamesString + StringPool.SLASH +
+						primitivePropertyExpression.getName(),
+					_objectDefinition),
+				primitivePropertyExpression);
+
+			return relationshipsNamesString + StringPool.SLASH + value;
+		}
 
 		relationshipsNames.add(propertyExpression.toString());
 
@@ -835,6 +883,20 @@ private Predicate _visitCollectionPropertyExpression(
 				_serviceTrackerMap));
 	}
 
+	private Object _visitPrimitivePropertyExpression(
+		EntityField entityField,
+		PrimitivePropertyExpression primitivePropertyExpression) {
+
+		if (entityField instanceof ReferenceStringEntityField) {
+			ReferenceStringEntityField referenceStringEntityField =
+				(ReferenceStringEntityField)entityField;
+
+			return referenceStringEntityField.getReferenceFieldName();
+		}
+
+		return primitivePropertyExpression.getName();
+	}
+
 	private static final Log _log = LogFactoryUtil.getLog(
 		PredicateExpressionVisitorImpl.class);
 

modules/apps/object/object-rest-test/src/testIntegration/java/com/liferay/object/rest/internal/manager/v1_0/test/DefaultObjectEntryManagerImplTest.java

@@ -2859,6 +2859,22 @@ public void testGetObjectEntries() throws Exception {
 
 		// Contains expression
 
+		testGetObjectEntries(
+			HashMapBuilder.put(
+				"filter",
+				_buildContainsExpressionFilterString(
+					_objectRelationshipERCObjectFieldName,
+					parentObjectEntry1.getExternalReferenceCode())
+			).build(),
+			childObjectEntry1);
+		testGetObjectEntries(
+			HashMapBuilder.put(
+				"filter",
+				_buildContainsExpressionFilterString(
+					_objectRelationshipERCObjectFieldName,
+					parentObjectEntry2.getExternalReferenceCode())
+			).build(),
+			childObjectEntry2);
 		testGetObjectEntries(
 			HashMapBuilder.put(
 				"filter",
@@ -3370,6 +3386,22 @@ public void testGetObjectEntries() throws Exception {
 
 		// "Starts with" expression
 
+		testGetObjectEntries(
+			HashMapBuilder.put(
+				"filter",
+				_buildStartsWithExpressionFilterString(
+					_objectRelationshipERCObjectFieldName,
+					parentObjectEntry1.getExternalReferenceCode())
+			).build(),
+			childObjectEntry1);
+		testGetObjectEntries(
+			HashMapBuilder.put(
+				"filter",
+				_buildStartsWithExpressionFilterString(
+					_objectRelationshipERCObjectFieldName,
+					parentObjectEntry2.getExternalReferenceCode())
+			).build(),
+			childObjectEntry2);
 		testGetObjectEntries(
 			HashMapBuilder.put(
 				"filter",