One to Many mapping with an intermediate table

Question

I thought I had this one pegged by mapping the intermediary table as a HasMany and between intermediary and child as HasOne, however HasOne expects to share a key. (No Inver

Answer 1

Why won't you make one-to-many from address to customer? Customer will contain foreign key then and address entity could be referened by other entity. In this case, you simply make References(x => x.Address); on customer table.
When I was trying to create one-to-one relation using FluentNHibernate, I faced common problems too. If you want to leave DB structure as you showed, I guess you should try the following mapping (with adding corresponding entity fields):

 public AddressMap()
 {
    Schema("dbo");
    Table("Address");
    Id(x => x.AddressId);
    Map(x => x.AddressType);
    HasOne(x => x.CustomerAddress).Cascade.All();
 }
 public CustomerAddressMap()
 {
     Schema("dbo");
     Table("CustomerAddress");
     Id(x => x.CustomerAddressId);
     Map(x => x.FromDate)
         .Not.Nullable();
     Map(x => x.ToDate);
     HasOne(x => x.Address)
     .Constrained()
     .ForeignKey();
 }

Such mapping left in my case one side empty, so I modified property setter for child entity (CustomerAddress):

public virtual Address Address
{ 
    get { return _address; }
    set 
    {
        _address = value;
        value.CustomerAddress = this;
    }
}

After these actions one-to-one worked fine) Hope it will help you to solve the problem.

Answer 2

map it as normal references

public class CustomerAddressMap : ClassMap<CustomerAddress>
{
    public CustomerAddressMap()
    {
        Table("CustomerAddress");

        Id(x => x.CustomerAddressId);
        Map(x => x.FromDate).Not.Nullable();
        Map(x => x.ToDate);
        References(x => x.Customer, "CustomerId");
        References(x => x.Address, "AddressId");
    }
}