DATAMONGO-805 - Excluding DBRef field in a query causes a MappingException.

Previously we tried to convert all DBRef associations into appropriate DBRef structures even if they were to be ignored. We now ignore excluded properties in DBRef associations correctly.

Original pull request: #102.

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

@@ -200,13 +200,28 @@ public class QueryMapper {
 			return getMappedKeyword(new Keyword((DBObject) value), null);
 		}
 
-		if (documentField.isAssociation()) {
+		if (isAssociationConversionNecessary(documentField, value)) {
 			return convertAssociation(value, documentField.getProperty());
 		}
 
 		return convertSimpleOrDBObject(value, documentField.getPropertyEntity());
 	}
 
+	/**
+	 * Returns whether the given {@link Field} represents an association reference that together with the given value
+	 * requires conversion to a {@link org.springframework.data.mongodb.core.mapping.DBRef} object. We check whether the
+	 * type of the given value is compatible with the type of the given document field in order to deal with potential
+	 * query field exclusions, since MongoDB uses the {@code int} {@literal 0} as an indicator for an excluded field.
+	 * 
+	 * @param documentField
+	 * @param value
+	 * @return
+	 */
+	private boolean isAssociationConversionNecessary(Field documentField, Object value) {
+		return documentField.isAssociation() && value != null
+				&& documentField.getProperty().getActualType().isAssignableFrom(value.getClass());
+	}
+
 	/**
 	 * Retriggers mapping if the given source is a {@link DBObject} or simply invokes the
 	 * 
@@ -248,7 +263,8 @@ public class QueryMapper {
 	 */
 	private Object convertAssociation(Object source, MongoPersistentProperty property) {
 
-		if (property == null || !property.isAssociation()) {
+		if (property == null || !property.isAssociation() || source == null || source instanceof DBRef
+				|| !property.isEntity()) {
 			return source;
 		}
 
@@ -270,7 +286,7 @@ public class QueryMapper {
 			return result;
 		}
 
-		return source == null || source instanceof DBRef ? source : converter.toDBRef(source, property);
+		return converter.toDBRef(source, property);
 	}
 
 	/**

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

@@ -56,6 +56,7 @@ import com.mongodb.QueryBuilder;
  * 
  * @author Oliver Gierke
  * @author Patryk Wasik
+ * @author Thomas Darimont
  */
 @RunWith(MockitoJUnitRunner.class)
 public class QueryMapperUnitTests {
@@ -466,6 +467,23 @@ public class QueryMapperUnitTests {
 		assertThat(result.get("myvalue"), is((Object) "$center"));
 	}
 
+	/**
+	 * @DATAMONGO-805
+	 */
+	@Test
+	public void shouldExcludeDBRefAssociation() {
+
+		Query query = query(where("someString").is("foo"));
+		query.fields().exclude("reference");
+
+		BasicMongoPersistentEntity<?> entity = context.getPersistentEntity(WithDBRef.class);
+		DBObject queryResult = mapper.getMappedObject(query.getQueryObject(), entity);
+		DBObject fieldsResult = mapper.getMappedObject(query.getFieldsObject(), entity);
+
+		assertThat(queryResult.get("someString"), is((Object) "foo"));
+		assertThat(fieldsResult.get("reference"), is((Object) 0));
+	}
+
 	class IdWrapper {
 		Object id;
 	}

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

@@ -24,6 +24,7 @@ import static org.springframework.data.mongodb.core.query.Update.*;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.HashMap;
+import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
 
@@ -49,6 +50,7 @@ import com.mongodb.MongoException;
 /**
  * @author Jon Brisbin
  * @author Oliver Gierke
+ * @author Thomas Darimont
  */
 public class MappingTests extends AbstractIntegrationTests {
 
@@ -465,6 +467,57 @@ public class MappingTests extends AbstractIntegrationTests {
 		assertThat(result.items.get(0).id, is(items.id));
 	}
 
+	/**
+	 * @see DATAMONGO-805
+	 */
+	@Test
+	public void supportExcludeDbRefAssociation() {
+
+		template.dropCollection(Item.class);
+		template.dropCollection(Container.class);
+
+		Item item = new Item();
+		template.insert(item);
+
+		Container container = new Container("foo");
+		container.item = item;
+
+		template.insert(container);
+
+		Query query = new Query(Criteria.where("id").is("foo"));
+		query.fields().exclude("item");
+		Container result = template.findOne(query, Container.class);
+
+		assertThat(result, is(notNullValue()));
+		assertThat(result.item, is(nullValue()));
+	}
+
+	/**
+	 * @see DATAMONGO-805
+	 */
+	@Test
+	public void shouldMapFieldsOfIterableEntity() {
+
+		template.dropCollection(IterableItem.class);
+		template.dropCollection(Container.class);
+
+		Item item = new IterableItem();
+		item.value = "bar";
+		template.insert(item);
+
+		Container container = new Container("foo");
+		container.item = item;
+
+		template.insert(container);
+
+		Query query = new Query(Criteria.where("id").is("foo"));
+		Container result = template.findOne(query, Container.class);
+
+		assertThat(result, is(notNullValue()));
+		assertThat(result.item, is(notNullValue()));
+		assertThat(result.item.value, is("bar"));
+	}
+
 	static class Container {
 
 		@Id final String id;
@@ -473,6 +526,10 @@ public class MappingTests extends AbstractIntegrationTests {
 			id = new ObjectId().toString();
 		}
 
+		public Container(String id) {
+			this.id = id;
+		}
+
 		@DBRef Item item;
 		@DBRef List<Item> items;
 	}
@@ -480,9 +537,26 @@ public class MappingTests extends AbstractIntegrationTests {
 	static class Item {
 
 		@Id final String id;
+		String value;
 
 		public Item() {
 			this.id = new ObjectId().toString();
 		}
 	}
+
+	static class IterableItem extends Item implements Iterable<ItemData> {
+
+		List<ItemData> data = new ArrayList<MappingTests.ItemData>();
+
+		@Override
+		public Iterator<ItemData> iterator() {
+			return data.iterator();
+		}
+	}
+
+	static class ItemData {
+
+		String id;
+		String value;
+	}
 }