Polishing.

Reorder methods and types. Rename MongoPersistentProperty.isOmitNullProperty to writeNullValues. Adapt caching MongoPersistentProperty and add tests.

Tweak Javadoc wording, add author and since tags.

See #3407
Original pull request: #3646.

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/convert/MappingMongoConverter.java

@@ -103,6 +103,7 @@ import com.mongodb.DBRef;
  * @author Mark Paluch
  * @author Roman Puchkovskiy
  * @author Heesu Jung
+ * @author Divya Srivastava
  */
 public class MappingMongoConverter extends AbstractMongoConverter implements ApplicationContextAware {
 
@@ -737,6 +738,7 @@ public class MappingMongoConverter extends AbstractMongoConverter implements App
 				continue;
 			}
 			if (prop.isAssociation()) {
+
 				writeAssociation(prop.getRequiredAssociation(), accessor, dbObjectAccessor);
 				continue;
 			}
@@ -744,13 +746,10 @@ public class MappingMongoConverter extends AbstractMongoConverter implements App
 			Object value = accessor.getProperty(prop);
 
 			if (value == null) {
-				if(!prop.isPropertyOmittableOnNull()) {
-					writeSimpleInternal(value, bson , prop);
+				if (prop.writeNullValues()) {
+					dbObjectAccessor.put(prop, null);
 				}
-				continue;
-			}
-
-			if (!conversions.isSimpleType(value.getClass())) {
+			} else if (!conversions.isSimpleType(value.getClass())) {
 				writePropertyInternal(value, dbObjectAccessor, prop);
 			} else {
 				writeSimpleInternal(value, bson, prop);
@@ -763,7 +762,14 @@ public class MappingMongoConverter extends AbstractMongoConverter implements App
 
 		MongoPersistentProperty inverseProp = association.getInverse();
 
-		writePropertyInternal(accessor.getProperty(inverseProp), dbObjectAccessor, inverseProp);
+		Object value = accessor.getProperty(inverseProp);
+
+		if (value == null && !inverseProp.isUnwrapped() && inverseProp.writeNullValues()) {
+			dbObjectAccessor.put(inverseProp, null);
+			return;
+		}
+
+		writePropertyInternal(value, dbObjectAccessor, inverseProp);
 	}
 
 	@SuppressWarnings({ "unchecked" })

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

@@ -41,6 +41,7 @@ import org.springframework.util.StringUtils;
  * @author Thomas Darimont
  * @author Christoph Strobl
  * @author Mark Paluch
+ * @author Divya Srivastava
  */
 public class BasicMongoPersistentProperty extends AnnotationBasedPersistentProperty<MongoPersistentProperty>
 		implements MongoPersistentProperty {
@@ -214,6 +215,19 @@ public class BasicMongoPersistentProperty extends AnnotationBasedPersistentPrope
 		return annotation != null ? annotation.order() : Integer.MAX_VALUE;
 	}
 
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.mapping.MongoPersistentProperty#skipNullValues()
+	 */
+	@Override
+	public boolean writeNullValues() {
+
+		org.springframework.data.mongodb.core.mapping.Field annotation = findAnnotation(
+				org.springframework.data.mongodb.core.mapping.Field.class);
+
+		return annotation != null && annotation.write() == Field.Write.ALWAYS;
+	}
+
 	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.mapping.model.AbstractPersistentProperty#createAssociation()
@@ -286,17 +300,4 @@ public class BasicMongoPersistentProperty extends AnnotationBasedPersistentPrope
 		return isAnnotationPresent(TextScore.class);
 	}
 
-	/*
-	 * (non-Javadoc)
-	 * @see org.springframework.data.mongodb.core.mapping.MongoPersistentProperty#isPropertyOmittableOnNull()
-	 */
-	public boolean isPropertyOmittableOnNull() {
-		org.springframework.data.mongodb.core.mapping.Field annotation = findAnnotation(
-				org.springframework.data.mongodb.core.mapping.Field.class);
-
-		if ( annotation != null && annotation.write().equals(Field.Write.ALWAYS) ) {
-			return false;
-		}
-		return true;
-	}
 }

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

@@ -33,6 +33,7 @@ public class CachingMongoPersistentProperty extends BasicMongoPersistentProperty
 	private boolean dbRefResolved;
 	private @Nullable DBRef dbref;
 	private @Nullable String fieldName;
+	private @Nullable Boolean writeNullValues;
 	private @Nullable Class<?> fieldType;
 	private @Nullable Boolean usePropertyAccess;
 	private @Nullable Boolean isTransient;
@@ -90,6 +91,20 @@ public class CachingMongoPersistentProperty extends BasicMongoPersistentProperty
 		return this.fieldName;
 	}
 
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.mapping.BasicMongoPersistentProperty#skipNullValues()
+	 */
+	@Override
+	public boolean writeNullValues() {
+
+		if (this.writeNullValues == null) {
+			this.writeNullValues = super.writeNullValues();
+		}
+
+		return this.writeNullValues;
+	}
+
 	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.mongodb.core.mapping.BasicMongoPersistentProperty#getFieldType()

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

@@ -28,27 +28,13 @@ import org.springframework.core.annotation.AliasFor;
  *
  * @author Oliver Gierke
  * @author Christoph Strobl
+ * @author Divya Srivastava
  */
 @Documented
 @Retention(RetentionPolicy.RUNTIME)
 @Target({ ElementType.FIELD, ElementType.METHOD, ElementType.ANNOTATION_TYPE })
 public @interface Field {
 
-	/**
-	 * Enumeration of write strategies for a field with null value.It decides whether a field with null value has to be
-	 * written to the resulting document to be saved to the database.
-	 */
-	enum Write{
-		/*
-		 * The field will always be written to the database irrespective of null value.
-		 */
-		ALWAYS,
-		/*
-		 * The field will only be written to the database if it has a non null value.
-		 */
-		NON_NULL
-	}
-
 	/**
 	 * The key to be used to store the field inside the document. Alias for {@link #name()}.
 	 *
@@ -82,12 +68,32 @@ public @interface Field {
 	FieldType targetType() default FieldType.IMPLICIT;
 
 	/**
-	 * If set to {@link Write#NON_NULL} {@literal null} values will be omitted.
-	 * Setting the value to {@link Write#ALWAYS} explicitly adds an entry for the given field
-	 * holding {@literal null} as a value {@code 'fieldName' : null }.
+	 * Write rules when to include a property value upon conversion. If set to {@link Write#NON_NULL} (default)
+	 * {@literal null} values are not written to the target {@code Document}. Setting the value to {@link Write#ALWAYS}
+	 * explicitly adds an entry for the given field holding {@literal null} as a value {@code 'fieldName' : null }.
 	 * <p />
-	 * <strong>NOTE</strong> Setting the value to {@link Write#ALWAYS} may lead to increased document size.
+	 * <strong>NOTE</strong>Setting the value to {@link Write#ALWAYS} may lead to increased document size.
+	 *
 	 * @return {@link Write#NON_NULL} by default.
+	 * @since 3.3
 	 */
 	Write write() default Write.NON_NULL;
+
+	/**
+	 * Enumeration of write strategies to define when a property is included for write conversion.
+	 *
+	 * @since 3.3
+	 */
+	enum Write {
+
+		/**
+		 * Value that indicates that property is to be always included, independent of value of the property.
+		 */
+		ALWAYS,
+
+		/**
+		 * Value that indicates that only properties with non-{@literal null} values are to be included.
+		 */
+		NON_NULL
+	}
 }

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

@@ -28,6 +28,7 @@ import org.springframework.lang.Nullable;
  * @author Patryk Wasik
  * @author Thomas Darimont
  * @author Christoph Strobl
+ * @author Divya Srivastava
  */
 public interface MongoPersistentProperty extends PersistentProperty<MongoPersistentProperty> {
 
@@ -54,6 +55,15 @@ public interface MongoPersistentProperty extends PersistentProperty<MongoPersist
 	 */
 	int getFieldOrder();
 
+	/**
+	 * Returns whether the property should be written to the database if its value is {@literal null}.
+	 *
+	 * @return
+	 * @since 3.3
+	 * @see Field.Write
+	 */
+	boolean writeNullValues();
+
 	/**
 	 * Returns whether the property is a {@link com.mongodb.DBRef}. If this returns {@literal true} you can expect
 	 * {@link #getDBRef()} to return an non-{@literal null} value.
@@ -104,24 +114,6 @@ public interface MongoPersistentProperty extends PersistentProperty<MongoPersist
 	 * @since 1.6
 	 */
 	boolean isTextScoreProperty();
-	
-	/**
-	 * Returns whether the property is to be written to the document if the value is null <br/>
-	 * It's annotated with {@link Field.Write}.
-	 *
-	 * @return
-	 * @since 1.6
-	 */
-	boolean isPropertyOmittableOnNull(); 
-
-	/**
-	 * Returns whether the property is to be written to the document if the value is null <br/>
-	 * It's annotated with {@link omitNull}.
-	 *
-	 * @return
-	 * @since 1.6
-	 */
-	boolean isOmitNullProperty(); 
 
 	/**
 	 * Returns the {@link DBRef} if the property is a reference.

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

@@ -63,6 +63,11 @@ class UnwrappedMongoPersistentProperty implements MongoPersistentProperty {
 		return delegate.getFieldOrder();
 	}
 
+	@Override
+	public boolean writeNullValues() {
+		return delegate.writeNullValues();
+	}
+
 	@Override
 	public boolean isDbReference() {
 		return delegate.isDbReference();
@@ -92,11 +97,6 @@ class UnwrappedMongoPersistentProperty implements MongoPersistentProperty {
 	public boolean isTextScoreProperty() {
 		return delegate.isTextScoreProperty();
 	}
-	
-	@Override
-	public boolean isOmitNullProperty() {
-		return delegate.isOmitNullProperty();
-	}
 
 	@Override
 	@Nullable
@@ -321,8 +321,4 @@ class UnwrappedMongoPersistentProperty implements MongoPersistentProperty {
 		return delegate.getAccessorForOwner(owner);
 	}
 
-	@Override
-	public boolean isPropertyOmittableOnNull() {
-		return delegate.isPropertyOmittableOnNull();
-	}
 }

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

@@ -24,6 +24,7 @@ import lombok.AllArgsConstructor;
 import lombok.Data;
 import lombok.EqualsAndHashCode;
 import lombok.NoArgsConstructor;
+import lombok.RequiredArgsConstructor;
 import lombok.Value;
 import lombok.With;
 
@@ -1692,7 +1693,7 @@ public class MongoTemplateTests {
 		assertThat(template.count(query, collectionName)).isEqualTo(1L);
 	}
 
-	@Test // DATAMONGO-571
+	@Test // DATAMONGO-571, GH-3407
 	public void nullsPropertiesForVersionObjectUpdates() {
 
 		VersionedPerson person = new VersionedPerson();
@@ -1702,11 +1703,17 @@ public class MongoTemplateTests {
 		template.save(person);
 		assertThat(person.id).isNotNull();
 
+		person.firstname = null;
 		person.lastname = null;
 		template.save(person);
 
 		person = template.findOne(query(where("id").is(person.id)), VersionedPerson.class);
+		assertThat(person.firstname).isNull();
 		assertThat(person.lastname).isNull();
+
+		org.bson.Document document = template.findOne(query(where("_id").is(person.id)), org.bson.Document.class,
+				"versionedPerson");
+		assertThat(document).doesNotContainKey("firstname").containsEntry("lastname", null);
 	}
 
 	@Test // DATAMONGO-571
@@ -3703,6 +3710,64 @@ public class MongoTemplateTests {
 		assertThat(template.find(new BasicQuery("{}").with(Sort.by("id")), WithIdAndFieldAnnotation.class)).isNotEmpty();
 	}
 
+	@Test // GH-3407
+	void shouldWriteSubdocumentWithNullCorrectly() {
+
+		template.dropCollection(WithSubdocument.class);
+
+		WithSubdocument doc = new WithSubdocument();
+		SubdocumentWithWriteNull subdoc = new SubdocumentWithWriteNull("Walter", "White");
+		doc.subdocument = subdoc;
+
+		template.save(doc);
+
+		org.bson.Document loaded = template.findById(doc.id, org.bson.Document.class, "withSubdocument");
+
+		assertThat(loaded.get("subdocument", org.bson.Document.class)).hasSize(3).containsEntry("firstname", "Walter")
+				.containsEntry("nickname", null);
+	}
+
+	@Test // GH-3407
+	void shouldUpdateSubdocumentWithNullCorrectly() {
+
+		template.dropCollection(WithSubdocument.class);
+
+		WithSubdocument doc = new WithSubdocument();
+		SubdocumentWithWriteNull subdoc = new SubdocumentWithWriteNull("Walter", "White");
+		subdoc.nickname = "Heisenberg";
+		doc.subdocument = subdoc;
+
+		template.save(doc);
+
+		String id = doc.id;
+
+		doc.id = null;
+		subdoc.nickname = null;
+		template.update(WithSubdocument.class).replaceWith(doc).findAndReplaceValue();
+
+		org.bson.Document loaded = template.findById(id, org.bson.Document.class, "withSubdocument");
+
+		assertThat(loaded.get("subdocument", org.bson.Document.class)).hasSize(3).containsEntry("firstname", "Walter")
+				.containsEntry("nickname", null);
+	}
+
+	@Test // GH-3407
+	void shouldFindSubdocumentWithNullCorrectly() {
+
+		template.dropCollection(WithSubdocument.class);
+
+		WithSubdocument doc = new WithSubdocument();
+		SubdocumentWithWriteNull subdoc = new SubdocumentWithWriteNull("Walter", "White");
+		doc.subdocument = subdoc;
+
+		template.save(doc);
+
+		org.bson.Document loaded = template.findOne(query(where("subdocument").is(subdoc)), org.bson.Document.class,
+				"withSubdocument");
+
+		assertThat(loaded).isNotNull();
+	}
+
 	private AtomicReference<ImmutableVersioned> createAfterSaveReference() {
 
 		AtomicReference<ImmutableVersioned> saved = new AtomicReference<>();
@@ -4020,7 +4085,8 @@ public class MongoTemplateTests {
 	static class VersionedPerson {
 
 		@Version Long version;
-		String id, firstname, lastname;
+		String id, firstname;
+		@Field(write = Field.Write.ALWAYS) String lastname;
 	}
 
 	static class TypeWithFieldAnnotation {
@@ -4247,4 +4313,22 @@ public class MongoTemplateTests {
 		String value;
 
 	}
+
+	@Data
+	static class WithSubdocument {
+
+		@Id //
+		@Field(name = "_id") //
+		String id;
+		SubdocumentWithWriteNull subdocument;
+	}
+
+	@Data
+	@RequiredArgsConstructor
+	static class SubdocumentWithWriteNull {
+
+		final String firstname, lastname;
+
+		@Field(write = Field.Write.ALWAYS) String nickname;
+	}
 }

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

@@ -1139,7 +1139,7 @@ public class MongoTemplateUnitTests extends MongoOperationsUnitTests {
 				.containsEntry("$geoNear.near.coordinates.[1]", 2D);
 	}
 
-	@Test // DATAMONGO-2155
+	@Test // DATAMONGO-2155, GH-3407
 	void saveVersionedEntityShouldCallUpdateCorrectly() {
 
 		when(updateResult.getModifiedCount()).thenReturn(1L);
@@ -1157,7 +1157,7 @@ public class MongoTemplateUnitTests extends MongoOperationsUnitTests {
 
 		assertThat(queryCaptor.getValue()).isEqualTo(new Document("_id", 1).append("version", 10));
 		assertThat(updateCaptor.getValue())
-				.isEqualTo(new Document("version", 11).append("_class", VersionedEntity.class.getName()));
+				.isEqualTo(new Document("version", 11).append("_class", VersionedEntity.class.getName()).append("name", null));
 	}
 
 	@Test // DATAMONGO-1783
@@ -2273,6 +2273,8 @@ public class MongoTemplateUnitTests extends MongoOperationsUnitTests {
 
 		@Id Integer id;
 		@Version Integer version;
+
+		@Field(write = Field.Write.ALWAYS) String name;
 	}
 
 	enum MyConverter implements Converter<AutogenerateableId, String> {

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/convert/MappingMongoConverterUnitTests.java

@@ -2520,6 +2520,18 @@ class MappingMongoConverterUnitTests {
 		assertThat(target.typeImplementingMap).isEqualTo(new TypeImplementingMap("one", 2));
 	}
 
+	@Test // GH-3407
+	void shouldWriteNullPropertyCorrectly() {
+
+		WithFieldWrite fieldWrite = new WithFieldWrite();
+
+		org.bson.Document document = new org.bson.Document();
+		converter.write(fieldWrite, document);
+
+		assertThat(document).containsEntry("writeAlways", null).doesNotContainKey("writeNonNull");
+		assertThat(document).containsEntry("writeAlwaysPerson", null).doesNotContainKey("writeNonNullPerson");
+	}
+
 	static class GenericType<T> {
 		T content;
 	}
@@ -3165,4 +3177,20 @@ class MappingMongoConverterUnitTests {
 			return null;
 		}
 	}
+
+	static class WithFieldWrite {
+
+		@org.springframework.data.mongodb.core.mapping.Field(
+				write = org.springframework.data.mongodb.core.mapping.Field.Write.NON_NULL) Integer writeNonNull;
+
+		@org.springframework.data.mongodb.core.mapping.Field(
+				write = org.springframework.data.mongodb.core.mapping.Field.Write.ALWAYS) Integer writeAlways;
+
+		@org.springframework.data.mongodb.core.mapping.DBRef @org.springframework.data.mongodb.core.mapping.Field(
+				write = org.springframework.data.mongodb.core.mapping.Field.Write.NON_NULL) Person writeNonNullPerson;
+
+		@org.springframework.data.mongodb.core.mapping.DBRef @org.springframework.data.mongodb.core.mapping.Field(
+				write = org.springframework.data.mongodb.core.mapping.Field.Write.ALWAYS) Person writeAlwaysPerson;
+
+	}
 }

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

@@ -48,25 +48,26 @@ import org.springframework.util.ReflectionUtils;
  * @author Oliver Gierke
  * @author Christoph Strobl
  * @author Mark Paluch
+ * @author Divya Srivastava
  */
 public class BasicMongoPersistentPropertyUnitTests {
 
-	MongoPersistentEntity<Person> entity;
+	private MongoPersistentEntity<Person> entity;
 
 	@BeforeEach
-	public void setup() {
+	void setup() {
 		entity = new BasicMongoPersistentEntity<>(ClassTypeInformation.from(Person.class));
 	}
 
 	@Test
-	public void usesAnnotatedFieldName() {
+	void usesAnnotatedFieldName() {
 
 		Field field = ReflectionUtils.findField(Person.class, "firstname");
 		assertThat(getPropertyFor(field).getFieldName()).isEqualTo("foo");
 	}
 
 	@Test
-	public void returns_IdForIdProperty() {
+	void returns_IdForIdProperty() {
 		Field field = ReflectionUtils.findField(Person.class, "id");
 		MongoPersistentProperty property = getPropertyFor(field);
 		assertThat(property.isIdProperty()).isTrue();
@@ -74,19 +75,19 @@ public class BasicMongoPersistentPropertyUnitTests {
 	}
 
 	@Test
-	public void returnsPropertyNameForUnannotatedProperties() {
+	void returnsPropertyNameForUnannotatedProperties() {
 
 		Field field = ReflectionUtils.findField(Person.class, "lastname");
 		assertThat(getPropertyFor(field).getFieldName()).isEqualTo("lastname");
 	}
 
 	@Test
-	public void preventsNegativeOrder() {
+	void preventsNegativeOrder() {
 		getPropertyFor(ReflectionUtils.findField(Person.class, "ssn"));
 	}
 
 	@Test // DATAMONGO-553
-	public void usesPropertyAccessForThrowableCause() {
+	void usesPropertyAccessForThrowableCause() {
 
 		BasicMongoPersistentEntity<Throwable> entity = new BasicMongoPersistentEntity<>(
 				ClassTypeInformation.from(Throwable.class));
@@ -96,7 +97,7 @@ public class BasicMongoPersistentPropertyUnitTests {
 	}
 
 	@Test // DATAMONGO-607
-	public void usesCustomFieldNamingStrategyByDefault() throws Exception {
+	void usesCustomFieldNamingStrategyByDefault() throws Exception {
 
 		ClassTypeInformation<Person> type = ClassTypeInformation.from(Person.class);
 		Field field = ReflectionUtils.findField(Person.class, "lastname");
@@ -113,7 +114,7 @@ public class BasicMongoPersistentPropertyUnitTests {
 	}
 
 	@Test // DATAMONGO-607
-	public void rejectsInvalidValueReturnedByFieldNamingStrategy() {
+	void rejectsInvalidValueReturnedByFieldNamingStrategy() {
 
 		ClassTypeInformation<Person> type = ClassTypeInformation.from(Person.class);
 		Field field = ReflectionUtils.findField(Person.class, "lastname");
@@ -126,49 +127,42 @@ public class BasicMongoPersistentPropertyUnitTests {
 	}
 
 	@Test // DATAMONGO-937
-	public void shouldDetectAnnotatedLanguagePropertyCorrectly() {
+	void shouldDetectAnnotatedLanguagePropertyCorrectly() {
 
 		MongoPersistentProperty property = getPropertyFor(DocumentWithLanguageProperty.class, "lang");
 		assertThat(property.isLanguageProperty()).isTrue();
 	}
 
 	@Test // DATAMONGO-937
-	public void shouldDetectImplicitLanguagePropertyCorrectly() {
+	void shouldDetectImplicitLanguagePropertyCorrectly() {
 
 		MongoPersistentProperty property = getPropertyFor(DocumentWithImplicitLanguageProperty.class, "language");
 		assertThat(property.isLanguageProperty()).isTrue();
 	}
 
 	@Test // DATAMONGO-976
-	public void shouldDetectTextScorePropertyCorrectly() {
+	void shouldDetectTextScorePropertyCorrectly() {
 
 		MongoPersistentProperty property = getPropertyFor(DocumentWithTextScoreProperty.class, "score");
 		assertThat(property.isTextScoreProperty()).isTrue();
 	}
 
-	@Test // DATAMONGO-2551
-	public void shouldDetectOmittableOnNullPropertyCorrectly() {
-
-		MongoPersistentProperty property = getPropertyFor(DocumentWithOmittableOnNullProperty.class, "write");
-		assertThat(property.isPropertyOmittableOnNull()).isTrue();
-	}
-
 	@Test // DATAMONGO-976
-	public void shouldDetectTextScoreAsReadOnlyProperty() {
+	void shouldDetectTextScoreAsReadOnlyProperty() {
 
 		MongoPersistentProperty property = getPropertyFor(DocumentWithTextScoreProperty.class, "score");
 		assertThat(property.isWritable()).isFalse();
 	}
 
 	@Test // DATAMONGO-1050
-	public void shouldNotConsiderExplicitlyNameFieldAsIdProperty() {
+	void shouldNotConsiderExplicitlyNameFieldAsIdProperty() {
 
 		MongoPersistentProperty property = getPropertyFor(DocumentWithExplicitlyRenamedIdProperty.class, "id");
 		assertThat(property.isIdProperty()).isFalse();
 	}
 
 	@Test // DATAMONGO-1050
-	public void shouldConsiderPropertyAsIdWhenExplicitlyAnnotatedWithIdEvenWhenExplicitlyNamePresent() {
+	void shouldConsiderPropertyAsIdWhenExplicitlyAnnotatedWithIdEvenWhenExplicitlyNamePresent() {
 
 		MongoPersistentProperty property = getPropertyFor(DocumentWithExplicitlyRenamedIdPropertyHavingIdAnnotation.class,
 				"id");
@@ -176,7 +170,7 @@ public class BasicMongoPersistentPropertyUnitTests {
 	}
 
 	@Test // DATAMONGO-1373
-	public void shouldConsiderComposedAnnotationsForIdField() {
+	void shouldConsiderComposedAnnotationsForIdField() {
 
 		MongoPersistentProperty property = getPropertyFor(DocumentWithComposedAnnotations.class, "myId");
 		assertThat(property.isIdProperty()).isTrue();
@@ -184,14 +178,14 @@ public class BasicMongoPersistentPropertyUnitTests {
 	}
 
 	@Test // DATAMONGO-1373
-	public void shouldConsiderComposedAnnotationsForFields() {
+	void shouldConsiderComposedAnnotationsForFields() {
 
 		MongoPersistentProperty property = getPropertyFor(DocumentWithComposedAnnotations.class, "myField");
 		assertThat(property.getFieldName()).isEqualTo("myField");
 	}
 
 	@Test // DATAMONGO-1737
-	public void honorsFieldOrderWhenIteratingOverProperties() {
+	void honorsFieldOrderWhenIteratingOverProperties() {
 
 		MongoMappingContext context = new MongoMappingContext();
 		MongoPersistentEntity<?> entity = context.getPersistentEntity(Sample.class);
@@ -203,36 +197,45 @@ public class BasicMongoPersistentPropertyUnitTests {
 		assertThat(properties).containsExactly("first", "second", "third");
 	}
 
+	@Test // GH-3407
+	void shouldDetectWritability() {
+
+		assertThat(getPropertyFor(WithFieldWrite.class, "fieldWithDefaults").writeNullValues()).isFalse();
+		assertThat(getPropertyFor(WithFieldWrite.class, "fieldWithField").writeNullValues()).isFalse();
+		assertThat(getPropertyFor(WithFieldWrite.class, "writeNonNull").writeNullValues()).isFalse();
+		assertThat(getPropertyFor(WithFieldWrite.class, "writeAlways").writeNullValues()).isTrue();
+	}
+
 	@Test // DATAMONGO-1798
-	public void fieldTypeShouldReturnActualTypeForNonIdProperties() {
+	void fieldTypeShouldReturnActualTypeForNonIdProperties() {
 
 		MongoPersistentProperty property = getPropertyFor(Person.class, "lastname");
 		assertThat(property.getFieldType()).isEqualTo(String.class);
 	}
 
 	@Test // DATAMONGO-1798
-	public void fieldTypeShouldBeObjectIdForPropertiesAnnotatedWithCommonsId() {
+	void fieldTypeShouldBeObjectIdForPropertiesAnnotatedWithCommonsId() {
 
 		MongoPersistentProperty property = getPropertyFor(Person.class, "id");
 		assertThat(property.getFieldType()).isEqualTo(ObjectId.class);
 	}
 
 	@Test // DATAMONGO-1798
-	public void fieldTypeShouldBeImplicitForPropertiesAnnotatedWithMongoId() {
+	void fieldTypeShouldBeImplicitForPropertiesAnnotatedWithMongoId() {
 
 		MongoPersistentProperty property = getPropertyFor(WithStringMongoId.class, "id");
 		assertThat(property.getFieldType()).isEqualTo(String.class);
 	}
 
 	@Test // DATAMONGO-1798
-	public void fieldTypeShouldBeObjectIdForPropertiesAnnotatedWithMongoIdAndTargetTypeObjectId() {
+	void fieldTypeShouldBeObjectIdForPropertiesAnnotatedWithMongoIdAndTargetTypeObjectId() {
 
 		MongoPersistentProperty property = getPropertyFor(WithStringMongoIdMappedToObjectId.class, "id");
 		assertThat(property.getFieldType()).isEqualTo(ObjectId.class);
 	}
 
 	@Test // DATAMONGO-2460
-	public void fieldTypeShouldBeDocumentForPropertiesAnnotatedIdWhenAComplexTypeAndFieldTypeImplicit() {
+	void fieldTypeShouldBeDocumentForPropertiesAnnotatedIdWhenAComplexTypeAndFieldTypeImplicit() {
 
 		MongoPersistentProperty property = getPropertyFor(WithComplexId.class, "id");
 		assertThat(property.getFieldType()).isEqualTo(Document.class);
@@ -304,9 +307,15 @@ public class BasicMongoPersistentPropertyUnitTests {
 		@TextScore Float score;
 	}
 
-	static class DocumentWithOmittableOnNullProperty {
+	static class WithFieldWrite {
 
-		@org.springframework.data.mongodb.core.mapping.Field("write") org.springframework.data.mongodb.core.mapping.Field.Write write;
+		int fieldWithDefaults;
+		@org.springframework.data.mongodb.core.mapping.Field int fieldWithField;
+		@org.springframework.data.mongodb.core.mapping.Field(
+				write = org.springframework.data.mongodb.core.mapping.Field.Write.NON_NULL) Integer writeNonNull;
+
+		@org.springframework.data.mongodb.core.mapping.Field(
+				write = org.springframework.data.mongodb.core.mapping.Field.Write.ALWAYS) Integer writeAlways;
 
 	}
 

src/main/asciidoc/new-features.adoc

@@ -5,6 +5,7 @@
 == What's New in Spring Data MongoDB 3.3
 
 * Extended support for <<mapping-usage.document-references, referencing>> entities.
+* Include/exclude `null` properties on write to `Document` through `@Field(write=…)`.
 
 [[new-features.3.2]]
 == What's New in Spring Data MongoDB 3.2