Why does Fluent NHibernate AutoMappings add an underscore to Id (e.g. Entity_id)?

Question

Hi using fluent nibernate automappings

to map this

    public virtual int Id { get; set; }
    /*...snip..*/
    public virtual MapMarkerIcon MapMarkerI         


        

Answer 1

You need an Id convention.

See http://wiki.fluentnhibernate.org/Available_conventions and http://wiki.fluentnhibernate.org/Convention_shortcut

Answer 2

None of the above links work. Here's the solution with links to current Fluent NHibernate & automapping documentation.

The issue (a simple example):

Say you have the simple example (from fluent's wiki) with an Entity and it's Value Objects in a List:

public class Product
{
  public virtual int Id { get; set; }
  //..
  public virtual Shelf { get; set; }
}

public class Shelf
{
  public virtual int Id { get;  set; }
  public virtual IList<Product> Products { get; set; }

  public Shelf()
  {
    Products = new List<Product>();
  }
}

With tables which have e.g.

Shelf 
id int identity

Product 
id int identity 
shelfid int

And a foreign key for shelfid -> Shelf.Id

---

You would get the error: invalid column name ... shelf_id

---

Solution:

Add a convention, it can be system wide, or more restricted.

ForeignKey.EndsWith("Id")

Code example:

var cfg = new StoreConfiguration();
var sessionFactory = Fluently.Configure()
  .Database(/* database config */)
  .Mappings(m =>
    m.AutoMappings.Add(
      AutoMap.AssemblyOf<Product>(cfg)
          .Conventions.Setup(c =>
              {
                  c.Add(ForeignKey.EndsWith("Id"));
              }
    )
  .BuildSessionFactory();

Now it will automap the ShelfId column to the Shelf property in Product.

---

More info

Wiki for Automapping

Table.Is(x => x.EntityType.Name + "Table")
PrimaryKey.Name.Is(x => "ID")
AutoImport.Never()
DefaultAccess.Field()
DefaultCascade.All()
DefaultLazy.Always()
DynamicInsert.AlwaysTrue()
DynamicUpdate.AlwaysTrue()
OptimisticLock.Is(x => x.Dirty())
Cache.Is(x => x.AsReadOnly())
ForeignKey.EndsWith("ID")

See more about Fluent NHibernate automapping conventions