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5065 empty map with document reference #5066

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b80d775
Add failing tests highlighting the bug
bamapookie Oct 6, 2025
ecc54ee
Return empty map instead of null when the property is a map
bamapookie Oct 6, 2025
dbda7b4
Adding tests for explicitly assigned nulls and repeating conversion t…
bamapookie Oct 16, 2025
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2 changes: 1 addition & 1 deletion .../src/main/java/org/springframework/data/mongodb/core/convert/ReferenceLookupDelegate.java
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Expand Up @@ -116,7 +116,7 @@ public ReferenceLookupDelegate(
}

if (!result.iterator().hasNext()) {
return null;
return property.isMap() ? Collections.emptyMap() : null;
}

Object resultValue = result.iterator().next();
Expand Down
82 changes: 81 additions & 1 deletion ...est/java/org/springframework/data/mongodb/core/convert/DefaultDbRefResolverUnitTests.java
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Expand Up @@ -21,10 +21,12 @@

import java.util.Arrays;
import java.util.Collections;
import java.util.Map;

import org.bson.Document;
import org.bson.types.ObjectId;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.DisplayName;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.extension.ExtendWith;
import org.mockito.ArgumentCaptor;
Expand All @@ -35,6 +37,8 @@
import org.mockito.quality.Strictness;

import org.springframework.dao.InvalidDataAccessApiUsageException;
import org.springframework.data.mapping.context.MappingContext;
import org.springframework.data.mapping.model.SpELContext;
import org.springframework.data.mongodb.MongoDatabaseFactory;
import org.springframework.data.mongodb.core.DocumentTestUtils;
import org.springframework.data.mongodb.core.MongoExceptionTranslator;
Expand All @@ -43,6 +47,9 @@
import com.mongodb.client.FindIterable;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoDatabase;
import org.springframework.data.mongodb.core.mapping.DocumentReference;
import org.springframework.data.mongodb.core.mapping.MongoPersistentEntity;
import org.springframework.data.mongodb.core.mapping.MongoPersistentProperty;

/**
* Unit tests for {@link DefaultDbRefResolver}.
Expand All @@ -58,6 +65,8 @@ class DefaultDbRefResolverUnitTests {
@Mock MongoDatabase dbMock;
@Mock MongoCollection<Document> collectionMock;
@Mock FindIterable<Document> cursorMock;
@Mock MappingContext<? extends MongoPersistentEntity<?>, MongoPersistentProperty> mappingContext;
@Mock SpELContext spELContext;
private DefaultDbRefResolver resolver;

@BeforeEach
Expand Down Expand Up @@ -91,7 +100,7 @@ void bulkFetchShouldLoadDbRefsCorrectly() {
}

@Test // DATAMONGO-1194
void bulkFetchShouldThrowExceptionWhenUsingDifferntCollectionsWithinSetOfReferences() {
void bulkFetchShouldThrowExceptionWhenUsingDifferentCollectionsWithinSetOfReferences() {

DBRef ref1 = new DBRef("collection-1", new ObjectId());
DBRef ref2 = new DBRef("collection-2", new ObjectId());
Expand Down Expand Up @@ -134,4 +143,75 @@ void bulkFetchContainsDuplicates() {

assertThat(resolver.bulkFetch(Arrays.asList(ref1, ref2))).containsExactly(document, document);
}

@Test // GH-5065
@DisplayName("GH-5065: Empty Map with @DocumentReference annotation should deserialize to an empty map.")
void resolveEmptyMapIsNotNull() {
DocumentReference documentReference = mock(DocumentReference.class);
when(documentReference.lookup()).thenReturn("{ '_id' : ?#{#target} }");
when(documentReference.sort()).thenReturn("");
when(documentReference.lazy()).thenReturn(false);
MongoPersistentProperty property = mock(MongoPersistentProperty.class);
when(property.isCollectionLike()).thenReturn(false);
when(property.isMap()).thenReturn(true);
when(property.isDocumentReference()).thenReturn(true);
when(property.getDocumentReference()).thenReturn(documentReference);
DocumentReferenceSource source = mock(DocumentReferenceSource.class);
when(source.getTargetSource()).thenReturn(Document.parse("{}"));
ReferenceLookupDelegate lookupDelegate = new ReferenceLookupDelegate(mappingContext, spELContext);

ReferenceResolver.MongoEntityReader entityReader = mock(ReferenceResolver.MongoEntityReader.class);

Object target = resolver.resolveReference(property, source, lookupDelegate, entityReader);

verify(property, times(3)).isMap();
verify(property, times(2)).isDocumentReference();
verify(property, times(2)).getDocumentReference();
verify(property, times(3)).isCollectionLike();
verify(documentReference, times(1)).lookup();
verify(documentReference, times(1)).sort();
verify(documentReference, times(1)).lazy();
verify(source, times(3)).getTargetSource();
verifyNoMoreInteractions(documentReference, property, source); // Make sure we only call the properties we mocked.
assertThat(target)
.isNotNull()
.isInstanceOf(Map.class);
}

@Test // GH-5065
@DisplayName("GH-5065: Lazy loaded empty Map with @DocumentReference annotation should deserialize to an empty map with a non-null values property.")
void resolveLazyLoadedEmptyMapIsNotNull() {
DocumentReference documentReference = mock(DocumentReference.class);
when(documentReference.lookup()).thenReturn("{ '_id' : ?#{#target} }");
when(documentReference.sort()).thenReturn("");
when(documentReference.lazy()).thenReturn(true);
MongoPersistentProperty property = mock(MongoPersistentProperty.class);
when(property.isCollectionLike()).thenReturn(false);
when(property.isMap()).thenReturn(true);
when(property.isDocumentReference()).thenReturn(true);
when(property.getDocumentReference()).thenReturn(documentReference);
//noinspection rawtypes,unchecked
when(property.getType()).thenReturn((Class) Map.class);
DocumentReferenceSource source = mock(DocumentReferenceSource.class);
when(source.getTargetSource()).thenReturn(Document.parse("{}"));
ReferenceLookupDelegate lookupDelegate = new ReferenceLookupDelegate(mappingContext, spELContext);

ReferenceResolver.MongoEntityReader entityReader = mock(ReferenceResolver.MongoEntityReader.class);

Object target = resolver.resolveReference(property, source, lookupDelegate, entityReader);

verify(property, times(1)).isMap();
verify(property, times(1)).isDocumentReference();
verify(property, times(1)).getDocumentReference();
verify(property, times(1)).isCollectionLike();
verify(property, times(1)).getType();
verify(documentReference, times(1)).lazy();
verify(source, times(1)).getTargetSource();
verifyNoMoreInteractions(documentReference, property, source); // Make sure we only call the properties we mocked.

assertThat(target)
.isNotNull()
.isInstanceOf(Map.class)
.asInstanceOf(MAP).values().isNotNull();
}
}
129 changes: 129 additions & 0 deletions ...c/test/java/org/springframework/data/mongodb/core/convert/MappingMongoConverterTests.java
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Expand Up @@ -34,13 +34,16 @@

import org.bson.Document;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.DisplayName;
import org.junit.jupiter.api.Nested;
import org.junit.jupiter.api.Test;

import org.springframework.data.annotation.Id;
import org.springframework.data.mongodb.MongoDatabaseFactory;
import org.springframework.data.mongodb.core.SimpleMongoClientDatabaseFactory;
import org.springframework.data.mongodb.core.convert.MongoCustomConversions.MongoConverterConfigurationAdapter;
import org.springframework.data.mongodb.core.mapping.DBRef;
import org.springframework.data.mongodb.core.mapping.DocumentReference;
import org.springframework.data.mongodb.core.mapping.MongoMappingContext;
import org.springframework.data.mongodb.test.util.Client;

Expand Down Expand Up @@ -478,4 +481,130 @@ public String toString() {
+ ", localTime=" + this.getLocalTime() + ", localDateTime=" + this.getLocalDateTime() + ")";
}
}

@Nested // GH-5065
@DisplayName("GH-5065: Empty Map Tests")
class EmptyMapTests {

@Test // GH-5065
@DisplayName("Test control: Passing test to indicate that the problem is not a more generic issue with maps in general.")
void readsEmptyMapCorrectly() {
org.bson.Document document = org.bson.Document.parse("{\"map\":{}}");
//EmptyMapDocument target = converter.read(EmptyMapDocument.class, document);
assertThat(converter.read(EmptyMapDocument.class, document).map).isNotNull().isEmpty();
assertThat(converter.read(EmptyMapDocument.class, document).getMap()).isNotNull().isEmpty();
}

@Test // GH-5065
@DisplayName("Test control: Converter should read an explicitly assigned null as a null map.")
void readsExplicitlyNullMapCorrectly() {
org.bson.Document document = org.bson.Document.parse("{\"map\":null}");
//EmptyMapDocument target = converter.read(EmptyMapDocument.class, document);
assertThat(converter.read(EmptyMapDocument.class, document).map).isNull();
assertThat(converter.read(EmptyMapDocument.class, document).getMap()).isNull();
}

@Test // GH-5065
@DisplayName("Converter should read an empty object as an empty map when using @DocumentReference.")
void readsEmptyMapWithDocumentReferenceCorrectly() {
org.bson.Document document = org.bson.Document.parse("{\"map\":{}}");
//DocumentReferenceEmptyMapDocument target = converter.read(DocumentReferenceEmptyMapDocument.class, document);
assertThat(converter.read(DocumentReferenceEmptyMapDocument.class, document).map).isNotNull().isEmpty();
assertThat(converter.read(DocumentReferenceEmptyMapDocument.class, document).getMap()).isNotNull().isEmpty();
}

@Test // GH-5065
@DisplayName("Converter should read an explicitly assigned null as a null map when using @DocumentReference.")
void readsExplicitlyNullMapWithDocumentReferenceCorrectly() {
org.bson.Document document = org.bson.Document.parse("{\"map\":null}");
//DocumentReferenceEmptyMapDocument target = converter.read(DocumentReferenceEmptyMapDocument.class, document);
assertThat(converter.read(DocumentReferenceEmptyMapDocument.class, document).map).isNull();
assertThat(converter.read(DocumentReferenceEmptyMapDocument.class, document).getMap()).isNull();
}

@Test // GH-5065
@DisplayName("Converter should read an empty object as an empty map with a valid values property when using @DocumentReference(lazy = true).")
void readsEmptyMapWithLazyLoadedDocumentReferenceCorrectly() {
org.bson.Document document = org.bson.Document.parse("{\"map\":{}}");
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I think it would also be interesting to have test for { 'map' : null } expecting null for the target.map.

//LazyDocumentReferenceEmptyMapDocument target = converter.read(LazyDocumentReferenceEmptyMapDocument.class, document);
assertThat(converter.read(LazyDocumentReferenceEmptyMapDocument.class, document).map).isNotNull().isEmpty();
assertThat(converter.read(LazyDocumentReferenceEmptyMapDocument.class, document).getMap()).isNotNull().isEmpty();
assertThat(converter.read(LazyDocumentReferenceEmptyMapDocument.class, document).map.values()).isNotNull().isEmpty();
assertThat(converter.read(LazyDocumentReferenceEmptyMapDocument.class, document).getMap().values()).isNotNull().isEmpty();
}

@Test // GH-5065
@DisplayName("Converter should read an empty object as an empty map when using @DBRef.")
void readsEmptyMapWithDBRefCorrectly() {
org.bson.Document document = org.bson.Document.parse("{\"map\":{}}");
//DBRefEmptyMapDocument target = converter.read(DBRefEmptyMapDocument.class, document);
assertThat(converter.read(DBRefEmptyMapDocument.class, document).map).isNotNull().isEmpty();
assertThat(converter.read(DBRefEmptyMapDocument.class, document).getMap()).isNotNull().isEmpty();
}

@Test // GH-5065
@DisplayName("Converter should read an explicitly assigned null as a null map when using @DBRef.")
void readsExplicitlyNullMapWithDBRefCorrectly() {
org.bson.Document document = org.bson.Document.parse("{\"map\":null}");
//DBRefEmptyMapDocument target = converter.read(DBRefEmptyMapDocument.class, document);
assertThat(converter.read(DBRefEmptyMapDocument.class, document).map).isNull();
assertThat(converter.read(DBRefEmptyMapDocument.class, document).getMap()).isNull();
}

static class EmptyMapDocument {

Map<String, String> map;

public EmptyMapDocument(Map<String, String> map) {
this.map = map;
}

Map<String, String> getMap() {
return map;
}
}

static class DocumentReferenceEmptyMapDocument {

@DocumentReference
Map<String, String> map;

public DocumentReferenceEmptyMapDocument(Map<String, String> map) {
this.map = map;
}

Map<String, String> getMap() {
return map;
}
}

static class LazyDocumentReferenceEmptyMapDocument {

@DocumentReference(lazy = true)
Map<String, String> map;

public LazyDocumentReferenceEmptyMapDocument(Map<String, String> map) {
this.map = map;
}

Map<String, String> getMap() {
return map;
}
}
}

static class DBRefEmptyMapDocument {

@DBRef
Map<String, String> map;

public DBRefEmptyMapDocument(Map<String, String> map) {
this.map = map;
}

Map<String, String> getMap() {
return map;
}
}

}
34 changes: 34 additions & 0 deletions .../java/org/springframework/data/mongodb/core/convert/ReferenceLookupDelegateUnitTests.java
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Expand Up @@ -19,8 +19,11 @@
import static org.mockito.Mockito.*;

import java.util.Collections;
import java.util.Map;

import org.bson.Document;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.DisplayName;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.extension.ExtendWith;
import org.mockito.Mock;
Expand Down Expand Up @@ -94,4 +97,35 @@ void shouldResolveEmptyMapOnEmptyTargetCollection() {
lookupDelegate.readReference(property, Collections.emptyMap(), lookupFunction, entityReader);
verify(lookupFunction, never()).apply(any(), any());
}

@Test // GH-5065
@DisplayName("GH-5065: Empty Map with @DocumentReference annotation should deserialize to an empty map.")
void shouldResolveEmptyMapOnEmptyDocumentReferenceMapProperty() {
DocumentReference documentReference = mock(DocumentReference.class);
when(documentReference.lookup()).thenReturn("{ '_id' : ?#{#target} }");
when(documentReference.sort()).thenReturn("");
MongoPersistentProperty property = mock(MongoPersistentProperty.class);
when(property.isMap()).thenReturn(true);
when(property.isDocumentReference()).thenReturn(true);
when(property.getDocumentReference()).thenReturn(documentReference);
when(property.isCollectionLike()).thenReturn(false);
DocumentReferenceSource source = mock(DocumentReferenceSource.class);
when(source.getTargetSource()).thenReturn(Document.parse("{}"));
ReferenceLookupDelegate.LookupFunction lookupFunction = mock(ReferenceLookupDelegate.LookupFunction.class);

Object target = lookupDelegate.readReference(property, source, lookupFunction, entityReader);

verify(lookupFunction, never()).apply(any(), any()); // Since we mocked it, make sure it is never called.
verify(property, times(2)).isMap();
verify(property, times(1)).isDocumentReference();
verify(property, times(1)).getDocumentReference();
verify(property, times(2)).isCollectionLike();
verify(documentReference, times(1)).lookup();
verify(documentReference, times(1)).sort();
verifyNoMoreInteractions(documentReference, property, source); // Make sure we only call the properties we mocked.
assertThat(target)
.isNotNull()
.isInstanceOf(Map.class);
}

}