Programming to interfaces while mapping with Fluent NHibernate

Question

I have been whipped into submission and have started learning Fluent NHibernate (no previous NHibernate experience). In my project, I am programming to interfaces to reduce

Answer 1

You can adjust your interface to contain only a getter:

public interface ISomeEntity
{
    int Id { get; }
}

Your concrete class can still implement a setter as well, and since you are programming to your interfaces you will never call the setter "by accident".

If you want to disallow setting the id even when you hold a reference to a concrete instance, you can refrain from implementing a setter, and then let NHibernate access the field instead of the property - that's right, NHibernate can use some nifty reflection trickery to set your id field directly instead of invoking the property. Then you might map the id like this:

Id(e => e.Id).Access.AsCamelCaseField();

in which case your Id property must be backed by a corresponding id field. There are more naming conventions, e.g. if you prefer underscores as private field prefix.