Handle cases where Nhibernate subclass does not exist
- by kaykayman
I have a scenario where I am using nhibernate to map records from one table to several different derived classes based on a discriminator.
public class BaseClass { }
public class DerivedClass0 : BaseClass { }
public class DerivedClass1 : BaseClass { }
public class DerivedClass2 : BaseClass { }
I then use nhibernate's DiscriminateSubClassesOnColumn() method and alter the configuration to include
<subclass name="DerivedClass0" extends="BaseClass" discriminator-value="discriminator0" />
<subclass name="DerivedClass1" extends="BaseClass" discriminator-value="discriminator1" />
<subclass name="DerivedClass2" extends="BaseClass" discriminator-value="discriminator2" />
so that when mapped, these classes are cast to their derived classes and not BaseClass.
However, there are some records in my database which have a discriminator which does not have a corresponding subclass. In these cases, nHibernate throws an error:
"Object with id: 'xxx' was not of the specified subclass..."
Is there some way I can handle this, so that any records which do not have a corresponding subclass are cast to BaseClass rather than an error being thrown?
I have simplified the above as much as possible, however it is worth noting that the XML is edited dynamically which is why I am referencing fluent nhibernate [DiscriminateSubClassesOnColumn()] and XML at the same time.
The following things (which would help) are not an option:
I cannot correct the data to remove records which are invalid
I cannot create subclasses for those records which do not have one
I need to handle cases where nHibernate tries to map on a discriminator and finds that one does not exist.
