ClassCastException when calling PathMetadata.getName()

[mnshdw]

Hello,

I recently upgraded from querydsl 2.9.0 to 3.2.3 and spring-data-mongodb 1.2.1.RELEASE to 1.3.1.RELEASE.

Currently, some of my MongoDB entities have inner objects stored using maps with Long keys :

@Document(collection = "xxx")
@QueryEntity
public class ObjectA {
    private Map<Long, ObjectB> objects;
}

When querying whether a key is present in the map (for example QObjectA.objectA.objects.get(objectId).isNotNull()), I now get a ClassCastException :

java.lang.ClassCastException: java.lang.Long cannot be cast to java.lang.String
    at com.mysema.query.types.PathMetadata.getName(PathMetadata.java:70)
    at org.springframework.data.mongodb.repository.support.SpringDataMongodbSerializer.getKeyForPath(SpringDataMongodbSerializer.java:66)

The getKeyForPath() method has changed between the two spring-data-mongodb releases : it was metadata.getExpression().toString() in the previous version, not getName(). However I'm not really sure whether the culprit is spring-data-mongodb or query-dsl. I noticed the PathMetadata code was rather "odd" : the generic type is never used, and the getName() method blindly casts the element to a String.

public String getName() {
    return (String)element;
}

Is this issue only related to query-dsl ?
Should I ask the spring-data guys for help ?
Any pointers in helping resolve this issue would be much appreciated.

[timowest]

This should be safer than the previous behaviour of taking the generic key object and calling toString(). You will get a ClassCastException for cases where the last path stage doesn't refer to a property.

This looks like a Spring Data issue.

[timowest]

I added a better Exception to guide the user to use getElement() instead for certain PathMetadata usage.