Fix Optional handling in query creation and result processing.

Original pull request: #3687.
Resolves #3656

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/mapping/MongoMappingContext.java

@@ -26,6 +26,7 @@ import org.springframework.data.mapping.model.FieldNamingStrategy;
 import org.springframework.data.mapping.model.Property;
 import org.springframework.data.mapping.model.PropertyNameFieldNamingStrategy;
 import org.springframework.data.mapping.model.SimpleTypeHolder;
+import org.springframework.data.util.NullableWrapperConverters;
 import org.springframework.data.util.TypeInformation;
 import org.springframework.lang.Nullable;
 
@@ -69,6 +70,11 @@ public class MongoMappingContext extends AbstractMappingContext<MongoPersistentE
 	 */
 	@Override
 	protected boolean shouldCreatePersistentEntityFor(TypeInformation<?> type) {
+
+		if(NullableWrapperConverters.supports(type.getType())) {
+			return false;
+		}
+
 		return !MongoSimpleTypes.HOLDER.isSimpleType(type.getType()) && !AbstractMap.class.isAssignableFrom(type.getType());
 	}
 

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/mapping/MongoMappingContextUnitTests.java

@@ -22,6 +22,7 @@ import java.util.AbstractMap;
 import java.util.Collections;
 import java.util.Locale;
 import java.util.Map;
+import java.util.Optional;
 
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
@@ -35,6 +36,7 @@ import org.springframework.data.mapping.PersistentProperty;
 import org.springframework.data.mapping.model.FieldNamingStrategy;
 
 import com.mongodb.DBRef;
+import org.springframework.data.util.TypeInformation;
 
 /**
  * Unit tests for {@link MongoMappingContext}.
@@ -173,6 +175,26 @@ public class MongoMappingContextUnitTests {
 		assertThat(context.getPersistentEntity(ChronoUnit.class)).isNull();
 	}
 
+	@Test // GH-3656
+	void shouldNotCreateEntityForOptionalGetter() {
+
+		MongoMappingContext context = new MongoMappingContext();
+		MongoPersistentEntity<?> entity = context.getRequiredPersistentEntity(InterfaceWithMethodReturningOptional.class);
+
+		assertThat(context.getPersistentEntities()).map(it -> it.getType()).doesNotContain((Class)
+				Optional.class).contains((Class)Person.class);
+	}
+
+	@Test // GH-3656
+	void shouldNotCreateEntityForOptionalField() {
+
+		MongoMappingContext context = new MongoMappingContext();
+		MongoPersistentEntity<?> entity = context.getRequiredPersistentEntity(ClassWithOptionalField.class);
+
+		assertThat(context.getPersistentEntities()).map(it -> it.getType()).doesNotContain((Class)
+				Optional.class).contains((Class)Person.class);
+	}
+
 	public class SampleClass {
 
 		Map<String, SampleClass> children;
@@ -244,4 +266,13 @@ public class MongoMappingContextUnitTests {
 
 		ChronoUnit unit;
 	}
+
+	interface InterfaceWithMethodReturningOptional {
+
+		Optional<Person> getPerson();
+	}
+
+	class ClassWithOptionalField {
+		Optional<Person> person;
+	}
 }

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/repository/AbstractPersonRepositoryIntegrationTests.java

@@ -1460,4 +1460,17 @@ public abstract class AbstractPersonRepositoryIntegrationTests {
 		List<Person> result = repository.findBySpiritAnimal(dave);
 		assertThat(result).map(Person::getId).containsExactly(josh.getId());
 	}
+
+	@Test //GH-3656
+	void resultProjectionWithOptionalIsExcecutedCorrectly() {
+
+		carter.setAddress(new Address("batman", "robin", "gotham"));
+		repository.save(carter);
+
+		PersonSummaryWithOptional result = repository.findSummaryWithOptionalByLastname("Beauford");
+
+		assertThat(result).isNotNull();
+		assertThat(result.getAddress()).isPresent();
+		assertThat(result.getFirstname()).contains("Carter");
+	}
 }

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/repository/PersonRepository.java

@@ -307,6 +307,8 @@ public interface PersonRepository extends MongoRepository<Person, String>, Query
 	// DATAMONGO-1030
 	PersonSummaryDto findSummaryByLastname(String lastname);
 
+	PersonSummaryWithOptional findSummaryWithOptionalByLastname(String lastname);
+
 	@Query("{ ?0 : ?1 }")
 	List<Person> findByKeyValue(String key, String value);
 

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/repository/PersonSummaryWithOptional.java

@@ -0,0 +1,24 @@
+/*
+ * Copyright 2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.repository;
+
+import java.util.Optional;
+
+public interface PersonSummaryWithOptional {
+
+	Optional<Address> getAddress();
+	Optional<String> getFirstname();
+}