DATAMONGO-1486 - Fix ClassCastException when mapping non-String Map key for updates.

We now make sure to convert Map keys into Strings when mapping update values for Map properties. Original pull request: #387.

Author: christophstrobl

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

@@ -1029,7 +1029,8 @@ public Object convertToMongoType(Object obj, TypeInformation<?> typeInformation)
 TypeInformation<? extends Object> valueTypeHint = typeHint != null && typeHint.getMapValueType() != null
 ? typeHint.getMapValueType() : typeHint;
 
-converted.put(convertToMongoType(entry.getKey()), convertToMongoType(entry.getValue(), valueTypeHint));
+converted.put(getPotentiallyConvertedSimpleWrite(entry.getKey()).toString(),
+convertToMongoType(entry.getValue(), valueTypeHint));
 }
 
 return new BasicDBObject(converted);

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

@@ -982,6 +982,24 @@ public void mappingShouldConsiderCustomConvertersForEnumMapKeys() {
 assertThat(result, isBsonObject().containing("$set.enumAsMapKey.V", 100));
 }
 
+/**
+ * @see DATAMONGO-1486
+ */
+@Test
+public void mappingShouldConvertMapKeysToString() {
+
+Update update = new Update().set("map", Collections.singletonMap(25, "#StarTrek50"));
+DBObject mappedUpdate = mapper.getMappedObject(update.getUpdateObject(),
+context.getPersistentEntity(EntityWithObjectMap.class));
+
+DBObject $set = getAsDBObject(mappedUpdate, "$set");
+DBObject mapToSet = getAsDBObject($set, "map");
+
+for (Object key : mapToSet.keySet()) {
+assertThat(key, instanceOf(String.class));
+}
+}
+
 static class DomainTypeWrappingConcreteyTypeHavingListOfInterfaceTypeAttributes {
 ListModelWrapper concreteTypeWithListAttributeOfInterfaceType;
 }