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Assign Value to Identity Column

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knovak72

Post subject: Assign Value to Identity Column

Posted: Thu Feb 07, 2008 6:38 am

Newbie

Joined: Thu Feb 07, 2008 6:28 am
Posts: 1

I have an object named PCSPrice with a property of Identifier and contains the related XML in the hbm file:

Code:

    <id name="Identifier" column="Identifier" type="Guid">
      <generator class="guid"/>
    </id>

What I want to do is assign a Guid in code like:

Code:

Guid identifier = Guid.NewGuid();

pcsPrice.Identifier = identifier;
anotherObject.Identifier = identifier;

//Save here

Right now whenever I call the above code, NHibernate creates a new Guid for the Identifier field - even though I've already assigned one. I've played around with the unsaved-value attribute but with no luck. How do I assign a Guid to an Identifier field without it being overwritten by NHibernate?

Thanks,

Kyle

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FlukeFan

Post subject: Assign Value to Identity Column

Posted: Thu Feb 07, 2008 9:24 am

Senior

Joined: Thu Jun 21, 2007 8:03 am
Posts: 127
Location: UK

Hi,

If you set the generator to 'assigned', then your application will be responsible for setting the identifier, rather than NHibernate.

Code:

    <id name="Identifier" column="Identifier" type="Guid"> 
      <generator class="assigned"/> 
    </id> 

Regards,
Richard

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SteveMc

Post subject:

Posted: Thu Feb 07, 2008 4:10 pm

Regular

Joined: Wed Aug 15, 2007 7:37 am
Posts: 73

If you want to be able to use both assigned and native id generation try something like this (although it's hard-coded to use type long for ids, and 0 as the unsaved-value, so you might want to mess around with it):

Code:

public class IdGenerator : NHibernate.Id.IdentityGenerator, NHibernate.Id.IIdentifierGenerator
{
  public new object Generate(NHibernate.Engine.ISessionImplementor session, object obj)
        {

            IEntityPersister persister = session.GetEntityPersister(obj);
  // Determine if an ID has been assigned.
            object id = persister.GetIdentifier(obj);
            if (id != null && (long)id != 0) return id;
            return IdentifierGeneratorFactory.IdentityColumnIndicator;
        }
}

In your mapping file:

Code:

<class name="TestClass" table="test_class">
      <id name="Id" column="id" type="long">
         <generator class="Namespace.IdGenerator, AssemblyName" />
      </id>
 ...

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