What is the difference between Fluent Mapping and Auto mapping in Fluent NHibernate - fluent-nhibernate

Question

After reading some of the articles about Fluent NHibernate I got confused from where to start
I have an existing database to which I need to create DataAccessLayer. I am new to NHibernate and FluentNhibernate. Since I understood that there is no need to write hbm.xml files, I picked Fluent Nhibernate.
So, What is FluentMapping? and AutoMapping?
I have created a classLibraryProject named FirstProject.Entities
I have created a class named "Customer"
namespace FirstProject.Entities
{
public class Customer
{
public virtual int CustomerID { get; set; }
public virtual string CustomerName { get; set; }
public virtual string Address1 { get; set; }
public virtual string Address2 { get; set; }
public virtual string City { get; set; }
public virtual string State { get; set; }
public virtual int Zip { get; set; }
}
}
Then I created a Mapping class
namespace FirstProject.Entities
{
public class CusotmerMap : ClassMap<Customer>
{
public CustomerMap()
{
Id(x => x.CustomerID).Column("CustomerID").GeneratedBy.Assigned();
Map(x => x.CustomerName);
Map(x => x.Address1);
Map(x => x.Address2);
Map(x => x.City);
Map(x => x.Zip);
}
}
}
I now don't know how to proceed further. Am I doing it right.. please suggest
how to configure and proceed further

Answer 1

The following is Fluent
Id(x => x.CustomerID).Column("CustomerID").GeneratedBy.Assigned();
I use Fluent assertions, like the following
actual.Should().BeGreaterThan(1).And().LessThan(2);
Fluent is basically where you chain together the commands such that it reads quite well.
Auto mapping is where you do nothing. Everything is done by conventions. I tend to use Auto. Fluent is nice if you don't follow conventions.
Based on your mapping, the CustomerId being Assigned is not the out-of-the-box convention. As such you need to either
Use Fluent to specify exactly how it should map. This is just like doing it the standard way in XML, but with a fluent interface.
Use Auto and specify a Convention that will automatically change CustomerId to be Assigned.
Use Auto and specify an Override, that will use Auto but override CustomerId to be Assigned.
If you want to do option 3, here is the code:
var model = AutoMap
.AssemblyOf<Customer>()
.Where(IsMapped)
.Override<Customer>(a => a.Id(b => b.CustomerId, "CustomerId").GeneratedBy.Assigned());
The function IsMapped must return True for entities you want to Map.