DATAMONGO-705 - Fixed handling of DBRefs in QueryMapper.

QueryMapper now converts values to become DBRefs correctly in getMappedKeyword(…). Added an exclusion path for the value handling in case we have an $exists keyword.

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

@@ -123,13 +123,13 @@ public class QueryMapper {
 	 * @param property
 	 * @return
 	 */
-	public DBObject getMappedKeyword(Keyword keyword, Field property) {
+	private DBObject getMappedKeyword(Keyword keyword, Field property) {
 
-		if (property.isAssociation()) {
-			convertAssociation(keyword.value, property.getProperty());
-		}
+		boolean needsAssociationConversion = property.isAssociation() && !keyword.isExists();
+		Object value = needsAssociationConversion ? convertAssociation(keyword.value, property.getProperty())
+				: getMappedValue(keyword.value, property.with(keyword.key));
 
-		return new BasicDBObject(keyword.key, getMappedValue(keyword.value, property.with(keyword.key)));
+		return new BasicDBObject(keyword.key, value);
 	}
 
 	/**
@@ -196,7 +196,7 @@ public class QueryMapper {
 	}
 
 	/**
-	 * Converts the given source assuming it's actually an association to anoter object.
+	 * Converts the given source assuming it's actually an association to another object.
 	 * 
 	 * @param source
 	 * @param property
@@ -256,7 +256,7 @@ public class QueryMapper {
 		String key;
 		Object value;
 
-		Keyword(Object source) {
+		public Keyword(Object source) {
 
 			Assert.isInstanceOf(DBObject.class, source);
 
@@ -268,6 +268,15 @@ public class QueryMapper {
 			this.value = value.get(key);
 		}
 
+		/**
+		 * Returns whether the current keyword is the {@code $exists} keyword.
+		 * 
+		 * @return
+		 */
+		public boolean isExists() {
+			return "$exists".equalsIgnoreCase(key);
+		}
+
 		/**
 		 * Returns whether the given value actually represents a keyword. If this returns {@literal true} it's safe to call
 		 * the constructor.
@@ -275,7 +284,7 @@ public class QueryMapper {
 		 * @param value
 		 * @return
 		 */
-		static boolean isKeyword(Object value) {
+		public static boolean isKeyword(Object value) {
 
 			if (!(value instanceof DBObject)) {
 				return false;

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

@@ -37,6 +37,7 @@ import org.springframework.data.annotation.Id;
 import org.springframework.data.mongodb.MongoDbFactory;
 import org.springframework.data.mongodb.core.DBObjectUtils;
 import org.springframework.data.mongodb.core.Person;
+import org.springframework.data.mongodb.core.mapping.BasicMongoPersistentEntity;
 import org.springframework.data.mongodb.core.mapping.DBRef;
 import org.springframework.data.mongodb.core.mapping.Field;
 import org.springframework.data.mongodb.core.mapping.MongoMappingContext;
@@ -63,8 +64,7 @@ public class QueryMapperUnitTests {
 	MongoMappingContext context;
 	MappingMongoConverter converter;
 
-	@Mock
-	MongoDbFactory factory;
+	@Mock MongoDbFactory factory;
 
 	@Before
 	public void setUp() {
@@ -334,7 +334,11 @@ public class QueryMapperUnitTests {
 		DBObject result = mapper.getMappedObject(query.getQueryObject(), context.getPersistentEntity(WithDBRef.class));
 
 		DBObject reference = DBObjectUtils.getAsDBObject(result, "reference");
-		assertThat(reference.containsField("$in"), is(true));
+
+		BasicDBList inClause = getAsDBList(reference, "$in");
+		assertThat(inClause, hasSize(2));
+		assertThat(inClause.get(0), is(instanceOf(com.mongodb.DBRef.class)));
+		assertThat(inClause.get(1), is(instanceOf(com.mongodb.DBRef.class)));
 	}
 
 	/**
@@ -394,6 +398,22 @@ public class QueryMapperUnitTests {
 		assertThat(mapped.get("_id"), is(instanceOf(ObjectId.class)));
 	}
 
+	/**
+	 * @see DATAMONGO-705
+	 */
+	@Test
+	public void convertsDBRefWithExistsQuery() {
+
+		Query query = query(where("reference").exists(false));
+
+		BasicMongoPersistentEntity<?> entity = context.getPersistentEntity(WithDBRef.class);
+		DBObject mappedObject = mapper.getMappedObject(query.getQueryObject(), entity);
+
+		DBObject reference = getAsDBObject(mappedObject, "reference");
+		assertThat(reference.containsField("$exists"), is(true));
+		assertThat(reference.get("$exists"), is((Object) false));
+	}
+
 	class IdWrapper {
 		Object id;
 	}
@@ -406,14 +426,12 @@ public class QueryMapperUnitTests {
 
 	class Sample {
 
-		@Id
-		private String foo;
+		@Id private String foo;
 	}
 
 	class BigIntegerId {
 
-		@Id
-		private BigInteger id;
+		@Id private BigInteger id;
 	}
 
 	enum Enum {
@@ -427,14 +445,12 @@ public class QueryMapperUnitTests {
 
 	class CustomizedField {
 
-		@Field("foo")
-		CustomizedField field;
+		@Field("foo") CustomizedField field;
 	}
 
 	class WithDBRef {
 
-		@DBRef
-		Reference reference;
+		@DBRef Reference reference;
 	}
 
 	class Reference {
@@ -449,7 +465,6 @@ public class QueryMapperUnitTests {
 
 	class WithMapDBRef {
 
-		@DBRef
-		Map<String, Sample> mapWithDBRef;
+		@DBRef Map<String, Sample> mapWithDBRef;
 	}
 }