How do I get automatic versioning in immutable subclass?

[Mikael Henriksson]

Ok the following works like a fucking charm (pardon the language) except that since I only do inserts it does not update the version automatically and I'd rather not leave that to whoever is writing the persistence service ;)

Any suggestions to how I can intercept and automatically increment the version where contact_id = ? and contact_version_id = ?. Do I need to use the event subsystem for that? Or can I solve it further in the mapping?

Note: ( ReadOnly() means "mutable=false" which prohibits deletes and updates.)

public class ParentMap : ClassMap<Parent>
{
    public ParentMap()
    {
        Table("parent_def");      
        Id(x => x.Id,"parent_id");
        Map(x => x.UID, "parent_uid").CustomSqlType("varchar").Length(40);
        Map(x => x.DeletedAt ,"dte_deleted").Nullable();
        Map(x => x.ModifiedAt, "dte_modified").Nullable();
        Map(x => x.CreatedAt, "dte_created").Nullable();
        Map(x => x.AutoUpdate, "auto_update").CustomSqlType("bit");
       
        HasMany(x => x.ParentVersions)
            .KeyColumn("parent_id")
            .Inverse()
            .Cascade.All();
    }
}
 
public class ParentVersionMap : ClassMap<ParentVersion>
{
    public ParentVersionMap()
    {
        Table("parent_version");
        ReadOnly();
 
        Id(x => x.Id  ,"parent_version_id");
        Version(x => x.Version)
            .Column("parent_version")
            .Generated.Never();
        Map(x => x.ParentHash ,"parent_hash")
            .CustomSqlType("varchar")
            .Length(40);
        Map(x => x.DateCreated ,"dte_created");
        Map(x => x.UpdateAvailable, "update_available");
 
        References(x => x.Parent, "parent_id")
            .ForeignKey("parent_id");
    }
}

[Fabio Maulo]

What mean "Version" (that is for optimistic-lock) in a no mutable entity ?

2009/11/19 Mikael Henriksson <mik...@zoolutions.se>

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Fabio Maulo

[Mikael Henriksson]

Ok I am terrible at explaining but here goes: You know how you have counters id columns (incremental identity). The version would be the incremental identity for the specific primary-key and foreign-key. So for every insert where the parent_id and the parent_version_id already exists it should autoincrement so this time around it would be more of a conditional counter I suppose. 

[Mikael Henriksson]

Pardon the primary key has nothing to do with it, only the forreign key. The primary key is just an identity.

[Mikael Henriksson]

One way of doing it is creating a preinsertevent like below but it feels wrong and it is an extra select for evert insert which feels wrong. Any other suggestions?

public bool OnPreInsert(PreInsertEvent @event)
{
    var entity = @event.Entity as ParentVersion;
    if (entity == null)
    {
        return false;
    }
 
    var currentMaxVersion = @event.Session.CreateCriteria<ParentVersion>("pv")
        .Add(Restrictions.Eq("pv.Parent.Id", entity.Parent.Id))
        .SetProjection(Projections.Max("pv.Version"))
        .UniqueResult<int>();
 
    Set(@event.Persister, @event.State, "ParentVersion", currentMaxVersion + 1);
 
    return false;
}