Fluent Nhibernate left join

问题

I want to map a class that result in a left outer join and not in an innner join.

My composite user entity is made by one table ("aspnet_users") and an some optional properties in a second table (like FullName in "users").

  public class UserMap : ClassMap<User> {
    public UserMap() {
        Table("aspnet_Users");
        Id(x => x.Id, "UserId").GeneratedBy.Guid();
        Map(x => x.UserName, "UserName");
        Map(x => x.LoweredUserName, "LoweredUserName");

       Join("Users",mm=>
                        {
                            mm.Map(xx => xx.FullName);

                        });
    }
}

this mapping result in an inner join select so no result come out is second table as no data. I'd like to generate an left join.

Is this possible only at query level?

回答1:

Try the Optional() method.

Join("Users", m =>
{
  m.Optional();
  m.Map(x => x.FullName);
});

回答2:

Only this did work for me (NH 3.3):

Join("OuterJoinTable",
                m =>
                {
                    m.Fetch.Join().Optional();
                    m.KeyColumn("ForeignKeyColumn");

                    m.Map(t => t.Field, "FieldName");
                });

来源：https://stackoverflow.com/questions/1354177/fluent-nhibernate-left-join