polymorphic hql
- by Berryl
I have a base type where "business id" must be unique for a given subclass, but it is possible for there to be different subclasses with the same business id.
If there is a base type with a requested id but of the wrong subclass I want to return null, using a named query. The code below does this, but I am wondering if I can avoid the try/catch with a better HQL. Can I?
Cheers,
Berryl
current hql
<query name="FindActivitySubjectByBusinessId">
<![CDATA[
from ActivitySubject act
where act.BusinessId = :businessId
]]>
</query>
current fetch code
public ActivitySubject FindByBusinessId<T>(string businessId) where T : ActivitySubject
{
Check.RequireStringValue(businessId, "businessId");
try {
return _session.GetNamedQuery("FindActivitySubjectByBusinessId")
.SetString("businessId", businessId)
.UniqueResult<T>();
}
catch (InvalidCastException e) {
// an Activity Subject was found with the requested id but the wrong type
return null;
}
}
