Fluent NHibernate join single column from another table

Question

Hi,

I'm using Fluent NHibernate and have two tables;

Customer [ID, Name, LanguageID]

Languages [ID, Description]

I have a Customer entity with the following properties; ID, Name, LanguageID, Language

What I would like to do is to join to the Languages table to get the language description and put it in the language property of the customer entity.

I have tried using Join but I can't get it to use the LanguageID field on the customer table to join to the Languages table - it keeps wanting to use 'ID'.

My mapping looks like;

        Table("Customers");
        Not.LazyLoad();
        Id(c => c.ID).GeneratedBy.Assigned();
        Map(c => c.Name);
        Map(c => c.LanguageID);
        Join("Languages", join =>
        {
            join.KeyColumn("ID");
            join.Map(prop => prop.Language).Column("Description");
        });

Answer 1

I haven't used Join before but I think you want the foreign key from Customer in your mapping:

    Table("ScriptActivities");
    Not.LazyLoad();
    Id(c => c.ID).GeneratedBy.Assigned();
    Map(c => c.Name);
    Map(c => c.LanguageID);
    Join("Languages", join =>
    {
        join.KeyColumn("LanguageID");
        join.Map(prop => prop.Language).Column("Description");
    });

Edited to add: The best example I could find on the join mapping is Ayende's blog. From that example, it appears to me that join is expecting the ID of the mapped object to be a foreign key in the joined table. Your schema has the joined table ID as a FK in the mapped object so join won't work. I suggest creating a view combining Customer and Language and mapping that.