To fix a regression from 2.x, DBCollection now handles a null Class argument to setObjectClass and setInternalClass

 JAVA-1901

Author: jyemin

driver/src/main/com/mongodb/DBCollectionObjectFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008-2014 MongoDB, Inc.
+ * Copyright 2008-2015 MongoDB, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -67,9 +67,12 @@ public DBCollectionObjectFactory update(final Class<? extends DBObject> aClass,
 
     private Map<List<String>, Class<? extends DBObject>> updatePathToClassMap(final Class<? extends DBObject> aClass,
                                                                               final List<String> path) {
-        Map<List<String>, Class<? extends DBObject>> map
-        = new HashMap<List<String>, Class<? extends DBObject>>(pathToClassMap);
-        map.put(path, aClass);
+        Map<List<String>, Class<? extends DBObject>> map = new HashMap<List<String>, Class<? extends DBObject>>(pathToClassMap);
+        if (aClass != null) {
+            map.put(path, aClass);
+        } else {
+            map.remove(path);
+        }
         return map;
     }
 
@@ -83,7 +86,7 @@ Class<? extends DBObject> getClassForPath(final List<String> path) {
     }
 
     private boolean isReflectionDBObject(final Class<? extends DBObject> aClass) {
-        return ReflectionDBObject.class.isAssignableFrom(aClass);
+        return aClass != null && ReflectionDBObject.class.isAssignableFrom(aClass);
     }
 
     private MongoInternalException createInternalException(final Class<? extends DBObject> aClass, final Exception e) {

driver/src/test/unit/com/mongodb/DBCollectionObjectFactoryTest.java

@@ -16,6 +16,7 @@
 
 package com.mongodb;
 
+import org.hamcrest.Matchers;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -84,6 +85,16 @@ public void testReflectionNestedObject() {
         assertThat(factory.getInstance(singletonList("Next")), instanceOf(Tweet.class));
     }
 
+    @Test
+    public void testThatNullObjectClassRevertsToDefault() {
+        factory = factory.update(Tweet.class, singletonList("a")).update(null);
+        assertThat(factory.getInstance(), Matchers.instanceOf(BasicDBObject.class));
+        assertThat(factory.getInstance(singletonList("a")), instanceOf(Tweet.class));
+
+        factory = factory.update(null, singletonList("a"));
+        assertThat(factory.getInstance(), Matchers.instanceOf(BasicDBObject.class));
+        assertThat(factory.getInstance(singletonList("a")), instanceOf(BasicDBObject.class));
+    }
 
     public static class TopLevelDBObject extends BasicDBObject {
         private static final long serialVersionUID = 7029929727222305692L;