or Create a profile

Home → Help and guidance →

Discriminate Sub Classes only for known types

fluxmunki's Avatar

fluxmunki

19 Feb, 2010 11:07 AM via web

I have a class mapped to a table and I'd like to create subclasses for some (but not all) of the values in one of the columns. Is this possible? For unknown values (those I don't specify as discriminator values) I'd like the base class to be used. I can see there's a

DiscriminatorPart.Default()

method, what does this do?

  1. Support Staff 2 Posted by James Gregory on 19 Feb, 2010 11:26 AM

    James Gregory's Avatar

    I believe that method is for setting the default value for the column during schema generation.

    I'm not certain if NHibernate supports a catch-all discriminator; normally you need to supply a specific value for the base-class discriminator, even if that value is null.

    Unless one of the other guys can shed some light on this, I suggest that you try using the overload to DiscriminateSubClassesOnColumn which allows you to set the base-class discriminator value and see how NHibernate behaves with any values you haven't declared.

    DiscriminateSubClassesOnColumn("DiscriminatorColumn", /* default value */);
DiscriminateSubClassesOnColumn("DiscriminatorColumn", null);

  2. 3 Posted by fluxmunki on 19 Feb, 2010 11:41 AM

    fluxmunki's Avatar

    Thanks, didn't spot the base class discriminator overload. I still can't find a way to make it work with unknown values. NH throws an exception for the first unknown discriminator value. I think it's an NH limitation.

    I'm now thinking I'll just use a different design.

  3. Support Staff 4 Posted by James Gregory on 19 Feb, 2010 11:46 AM

    James Gregory's Avatar

    Yeah, I'm fairly certain NHibernate needs to know about every possible value
    in that column. I would suggest adjusting your design to accommodate this.

  4. James Gregory closed this discussion on 19 Feb, 2010 12:06 PM.

Comments are currently closed for this discussion. You can start a new one.

2 people watching.

  • New Issue

  • Conversation Started

  • The discussion is closed

    No more actions from Fluent NHibernate or the discussion starter are required.

  • Re-open the discussion

Recent Discussions

09 Dec, 2010 09:42 AM Property formula is not working.
08 Dec, 2010 05:24 PM Setting length on composite -key property
02 Dec, 2010 09:33 PM Setting Component as Unique Key
02 Dec, 2010 07:29 PM Conventions for ICompositeUserTypes and field overrides
26 Nov, 2010 01:24 PM Maping details collection using interface for detail

 

22 Nov, 2010 09:59 PM Mapping a view without a unique id column
22 Nov, 2010 09:27 PM <many-to-one> and access setting
18 Nov, 2010 03:32 PM Control the name of the Primary Key and Unique Constraint Names
18 Nov, 2010 03:00 PM ForeignKeyConstraintName for References
14 Nov, 2010 12:40 PM SQLite Versioning Configuration Question