DATAMONGO-493 - Fixed broken $ne handling in QueryMapper.

$ne expressions are now only being tried to be converted into an ObjectId in case they follow an id property. Previously they tried in every case which might have led to Strings being converted into ObjectIds that accidentally were valid ObjectIds but didn't represent an id at all.

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

@@ -86,6 +86,8 @@ public class QueryMapper {
 							ids.add(convertId(id));
 						}
 						valueDbo.put(inKey, ids.toArray(new Object[ids.size()]));
+					} else if (valueDbo.containsField("$ne")) {
+						valueDbo.put("$ne", convertId(valueDbo.get("$ne")));
 					} else {
 						value = getMappedObject((DBObject) value, null);
 					}
@@ -102,8 +104,6 @@ public class QueryMapper {
 					newConditions.add(getMappedObject((DBObject) iter.next(), null));
 				}
 				value = newConditions;
-			} else if (key.equals("$ne")) {
-				value = convertId(value);
 			}
 
 			newDbo.put(newKey, convertSimpleOrDBObject(value, null));

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

@@ -21,7 +21,9 @@ import static org.springframework.data.mongodb.core.query.Criteria.*;
 import static org.springframework.data.mongodb.core.query.Query.*;
 
 import java.math.BigInteger;
+import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.List;
 
 import org.bson.types.ObjectId;
 import org.junit.Before;
@@ -211,6 +213,25 @@ public class QueryMapperUnitTests {
 		assertThat(((DBObject) result.get("nested")).get("id"), is(instanceOf(String.class)));
 	}
 
+	/**
+	 * @see DATAMONGO-493
+	 */
+	@Test
+	public void doesNotTranslateNonIdPropertiesFor$NeCriteria() {
+
+		ObjectId accidentallyAnObjectId = new ObjectId();
+
+		Query query = Query.query(Criteria.where("id").is("id_value").and("publishers")
+				.ne(accidentallyAnObjectId.toString()));
+
+		DBObject dbObject = mapper.getMappedObject(query.getQueryObject(), context.getPersistentEntity(UserEntity.class));
+		assertThat(dbObject.get("publishers"), is(instanceOf(DBObject.class)));
+
+		DBObject publishers = (DBObject) dbObject.get("publishers");
+		assertThat(publishers.containsField("$ne"), is(true));
+		assertThat(publishers.get("$ne"), is(instanceOf(String.class)));
+	}
+
 	class IdWrapper {
 		Object id;
 	}
@@ -236,4 +257,9 @@ public class QueryMapperUnitTests {
 	enum Enum {
 		INSTANCE;
 	}
+
+	class UserEntity {
+		String id;
+		List<String> publishers = new ArrayList<String>();
+	}
 }