HHH-957 - SubqueryExpression throws ClassCastException on DetachedCriteria subqueries

see http://opensource.atlassian.com/projects/hibernate/browse/HHH-957

The toSqlString() method in SubqueryExpression contains a line that casts a Criteria object to CriteriaImpl in order to call the getSession() method. However, if DetachedCriteria is used as a subquery in a Criteria query, the underlying Criteria object will be CriteriaImpl.Subcriteria, thus a ClassCastException will be thrown.

I have created a bug fix. Add the following method to SubqueryExpression:

private SessionImpl getSessionImpl(Criteria criteria) {
SessionImpl session = null;
if (criteria instanceof CriteriaImpl)

{ CriteriaImpl impl = (CriteriaImpl)criteria; session = impl.getSession(); }

else if (criteria instanceof CriteriaImpl.Subcriteria)

{ CriteriaImpl.Subcriteria sub = (CriteriaImpl.Subcriteria)criteria; //Alert! Recursive call here! session = getSessionImpl(sub.getParent()); }

return session;
}

And then replace the offending line in toSqlString() with a call to the new method.

Attached is SubqueryExpression with proposed changes in place.