C# – Using MyGeneration with Fluent NHibernate

To get a bidirectional association with a not-null foreign key column in the Details table you can add the suggested Owner property, a References(...).CanNotBeNull() mapping in the DetailsMap class, and make the Summary end inverse.

To avoid having two different foreign key columns for the two association directions, you can either specify the column names manually or name the properties in a way that gives the same column name for both directions. In this case you I suggest renaming the Details.Owner property to Details.Summary.

I made the Summary id generated by increment to avoid problems when inserting into the table since Summary currenty has no columns besides id.

Domain:

public class Detail
{
    public int id { get; protected set; }
    public string ItemName { get; set; }

    // Renamed to use same column name as specified in the mapping of Summary.Details
    public Summary Summary {get; set;} 
}

public class Summary
{
    public Summary()
    {
        Details = new List<Detail>();
    }

    public int id { get; protected set; }
    public IList<Detail> Details { get; protected set; }
}

Mapping:

public class DetailMap : ClassMap<Detail>
{
    public DetailMap()
    {
        Id(x => x.id)
            .GeneratedBy.Native();

        Map(x => x.ItemName)
            .CanNotBeNull();

        References<Summary>(x => x.Summary)
            // If you don't want to rename the property in Summary,
            // you can do this instead:
            // .TheColumnNameIs("Summary_id")
            .CanNotBeNull();
    }
}

public class SummaryMap : ClassMap<Summary>
{
    public SummaryMap()
    {
        Id(x => x.id)
            .GeneratedBy.Increment();

        HasMany<Detail>(x => x.Details)
            .IsInverse()
            .AsBag(); // Use bag instead of list to avoid index updating issues
    }
}

I strongly recommend you take a look at Visual NHibernate from Slyce. I have used all tools out there both free and commercial and found it to be the only one that does exactly what it says on the can and more.

It allows you to design your entities either from the ground up or from an existing database.
_{(source: slyce.com)}

It is compatible with most existing dbs

with future suport for Postgresql.

It allows you to customise your entities to your specs
_{(source: slyce.com)}

Other than its ability to go back and forth smoothly between entities and db during design, my most favorate feature is the Diff View

_{(source: slyce.com)}

which shows changes it will make to code before it generates the code. So not only can you see the effect of your changes but you can also cancel the codegeneration in time or simply output to a different folder.

This tool has many many fine features and is now mature. Lastly, there is a 30% discount going on so ;-)