Fluent Nhibernate Many-to-Many mapping with extra column - fluent-nhibernate

Question

I want to map sth like this using fluent Nhibernate but I am not sure how to map the inventory table
This is the tables I have :
Product (Id,Name, ...)
Warehouse(Id, Name, ...)
Inventory(Product_id, Warehouse_id, StockInHand)
and Mappings like below
Public ProductMap()
{
Id(x => x.Id);
Map(x => x.Name);
HasManyToMany(x => x.StoresStockedIn)
.Cascade.All()
.Inverse()
.Table("Inventory");
}
public WarehouseMap()
{
Id(x => x.Id);
Map(x => x.Name);
HasManyToMany(x => x.Products)
.Cascade.All()
.Table("Inventory");
}
The problem I face is that how can I map the StockInHand (how should the inventory model mapping?).
or are there other way to model this scenario ?
I have read some existing questions but not yet get clear understand what to do.
Thanks

Answer 1

Your relationship is not a many-to-many as far as NHibernate is concerned. A true many-to-many has no additional columns, such as StockInHand in your example.
You have to map this as two one-to-many relationships, and map Inventory as an entity.
Something like (i've skipped the other properties):
public class Product
{
public List<Inventory> Inventory { get; set; }
}
public class Warehouse
{
public List<Inventory> Inventory { get; set; }
}
public class Inventory
{
public Product Product { get; set; }
public Warehouse Warehouse { get; set; }
public bool StockInHand { get; set; }
}
public ProductMap() {
Id(x => x.Id);
Map(x => x.Name);
HasMany(x => x.Inventory)
.Cascade.All()
.Inverse()
.Table("Inventory");
}
public WarehouseMap()
{
Id(x => x.Id);
Map(x => x.Name);
HasMany(x => x.Inventory)
.Cascade.All()
.Inverse()
.Table("Inventory");
}
public InventoryMap()
{
CompositeId()
.KeyReference(x => x.Product, "Product_id")
.KeyReference(x => x.Warehouse, "Warehouse_id")
Map(x => x.StockInHand);
}