Query document reference by object with id

works :)

Author: christophstrobl

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

@@ -577,6 +577,35 @@ public DBRef toDBRef(Object object, @Nullable MongoPersistentProperty referringP
 		return createDBRef(object, referringProperty);
 	}
 
+	public Object toDocumentReference(Object source, @Nullable MongoPersistentProperty referringProperty) {
+
+		if (source instanceof LazyLoadingProxy) {
+			return ((LazyLoadingProxy) source).getSource();
+		}
+
+		if (referringProperty != null) {
+
+			if (referringProperty.isDbReference()) {
+				return toDBRef(source, referringProperty);
+			}
+			if (referringProperty.isDocumentReference()) {
+				return createDocumentPointer(source, referringProperty);
+			}
+		}
+
+		throw new RuntimeException("oops - what's that " + source);
+	}
+
+	Object createDocumentPointer(Object source, @Nullable MongoPersistentProperty referringProperty) {
+
+		if (conversionService.canConvert(referringProperty.getType(), DocumentPointer.class)) {
+			return conversionService.convert(source, DocumentPointer.class).getPointer();
+		}
+
+		return mappingContext.getPersistentEntity(referringProperty.getAssociationTargetType())
+				.getIdentifierAccessor(source).getIdentifier();
+	}
+
 	/**
 	 * Root entry method into write conversion. Adds a type discriminator to the {@link Document}. Shouldn't be called for
 	 * nested conversions.

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

@@ -70,4 +70,8 @@ default Object convertToMongoType(@Nullable Object obj, MongoPersistentEntity<?>
 	 * @return will never be {@literal null}.
 	 */
 	DBRef toDBRef(Object object, @Nullable MongoPersistentProperty referingProperty);
+
+	default Object toDocumentReference(Object source, @Nullable MongoPersistentProperty referringProperty) {
+		return toDBRef(source, referringProperty);
+	}
 }

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

@@ -605,7 +605,7 @@ protected Object convertAssociation(@Nullable Object source, @Nullable MongoPers
 		if (source instanceof Iterable) {
 			BasicDBList result = new BasicDBList();
 			for (Object element : (Iterable<?>) source) {
-				result.add(createDbRefFor(element, property));
+				result.add(createReferenceFor(element, property));
 			}
 			return result;
 		}
@@ -614,12 +614,12 @@ protected Object convertAssociation(@Nullable Object source, @Nullable MongoPers
 			Document result = new Document();
 			Document dbObject = (Document) source;
 			for (String key : dbObject.keySet()) {
-				result.put(key, createDbRefFor(dbObject.get(key), property));
+				result.put(key, createReferenceFor(dbObject.get(key), property));
 			}
 			return result;
 		}
 
-		return createDbRefFor(source, property);
+		return createReferenceFor(source, property);
 	}
 
 	/**
@@ -666,12 +666,16 @@ private Entry<String, Object> createMapEntry(String key, @Nullable Object value)
 		return Collections.singletonMap(key, value).entrySet().iterator().next();
 	}
 
-	private DBRef createDbRefFor(Object source, MongoPersistentProperty property) {
+	private Object createReferenceFor(Object source, MongoPersistentProperty property) {
 
 		if (source instanceof DBRef) {
 			return (DBRef) source;
 		}
 
+		if(property != null &&  property.isDocumentReference()) {
+			return converter.toDocumentReference(source, property);
+		}
+
 		return converter.toDBRef(source, property);
 	}
 

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

@@ -584,6 +584,28 @@ void loadCollectionReferenceWithMissingRefs() {
 		assertThat(result.getSimpleValueRef()).containsExactly(new SimpleObjectRef("ref-2", "me-the-2-referenced-object"));
 	}
 
+	@Test // GH-3602
+	void queryForReference() {
+
+		String collectionB = template.getCollectionName(WithRefB.class);
+
+		WithRefB b = new WithRefB();
+		b.id = "b";
+		template.save(b);
+
+		WithRefA a = new WithRefA();
+		a.id = "a";
+		a.toB = b;
+		template.save(a);
+
+		WithRefA a2 = new WithRefA();
+		a2.id = "a2";
+		template.save(a2);
+
+		WithRefA loadedA = template.query(WithRefA.class).matching(where("toB").is(b)).firstValue();
+		assertThat(loadedA.getId()).isEqualTo(a.getId());
+	}
+
 	@Data
 	static class SingleRefRoot {
 

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

@@ -48,6 +48,7 @@
 import org.springframework.data.mongodb.core.geo.GeoJsonPolygon;
 import org.springframework.data.mongodb.core.mapping.DBRef;
 import org.springframework.data.mongodb.core.mapping.Document;
+import org.springframework.data.mongodb.core.mapping.DocumentReference;
 import org.springframework.data.mongodb.core.mapping.Field;
 import org.springframework.data.mongodb.core.mapping.FieldType;
 import org.springframework.data.mongodb.core.mapping.MongoMappingContext;
@@ -1487,4 +1488,32 @@ static class WithPropertyUsingUnderscoreInName {
 		@Field("renamed")
 		String renamed_fieldname_with_underscores;
 	}
+
+	static class WithDocumentReferences {
+
+		@DocumentReference
+		Sample sample;
+
+		@DocumentReference
+		SimpeEntityWithoutId noId;
+
+		@DocumentReference(lookup = "{ 'stringProperty' : ?#{stringProperty} }")
+		SimpeEntityWithoutId noIdButLookupQuery;
+
+	}
+	
+	@Test
+	void xxx() {
+		
+		Sample sample = new Sample();
+		sample.foo = "sample-id";
+
+		Query query = query(where("sample").is(sample));
+		
+		org.bson.Document mappedObject = mapper.getMappedObject(query.getQueryObject(),
+				context.getPersistentEntity(WithDocumentReferences.class));
+		
+		System.out.println("mappedObject.toJson(): " + mappedObject.toJson());
+	}
+
 }