nHibernate, No row with the given identifier exists

Question

I have a mapping along the lines of this.

Answer 1

Try that...

public void Override(ModelMapper modelMapper) {
    modelMapper.Class<T>(c => { 
        c.ManyToOne(m => m.FKObj, r => {
            r.Column("FKColumn");
            r.NotFound(NotFoundMode.Ignore); // THIS IS IMPORTANT!!!
        });
    });
}

Answer 2

Ok, I found the answer. Add the

not-found="ignore"

attribute to the property KeyField:

<many-to-one name="KeyField" not-found="ignore" class="Model.Entities.Key, Model" column="field_id" />

Answer 3

In my case the problem was because a foreign key constraint was not enforced by MyISAM engine and therefore one of the rows ended up pointing to a non-existant value and the proxy threw an exception. I would recommend checking your dataset is consistent in this case.