NHibernate数据检索问题

这些代码在保存数据时运行良好。

但它无法从中检索数据 b_TeacherDetail -桌子。例如:

TeacherRepository tRep = new TeacherRepository();
Teacher t = tRep.Get(12);

在这里, t.TeacherDetail 是 null . 但我知道有一个条目 b\教师详图 -教师id 12的桌子。

我的桌子是:

Teacher {ID, Name, IsActive, DesignationID, DepartmentID}
TeacherDetail {ID, TeacherID, Address, MobileNo}

public class Teacher
    {
        public virtual int ID { get; set; }
        public virtual string Name { get; set; }
        public virtual bool IsActive { get; set; }        
        public virtual TeacherDetail TeacherDetail { get; set; }

        public virtual Designation Designation { get; set; }
        public virtual Department Department { get; set; }        
    }

教师详情.cs

public class TeacherDetail
    {
        public virtual int ID { get; set; }
        public virtual Teacher Teacher { get; set; }
        public virtual string Address { get; set; }
        public virtual string MobileNo { get; set; }
    }

<class name="Teacher" table="b_Teacher">
    <id name="ID" column="ID">
      <generator class="native"/>
    </id>

    <property name="Name" column="Name" />
    <property name="IsActive" column="IsActive" />

    <one-to-one class="TeacherDetail" name="TeacherDetail" cascade="all" />

    <many-to-one name="Department" class="Department" unique="true" column="DepartmentID" />
    <many-to-one name="Designation" class="Designation" unique="true" column="DesignationID" />
  </class>

TeacherDetail.hbm.xml文件

<class name="TeacherDetail" table="b_TeacherDetail">
    <id name="ID" column="ID">
      <generator class="native"/>
    </id>

    <property name="Address" column="Address" />
    <property name="MobileNo" column="MobileNo" />

    <many-to-one name="Teacher" class="Teacher" column="TeacherID" unique="true" />
  </class>

public class Repository<T> : IRepository<T>
    {
        ... ... ...

        public T Get(object id)
        {
            T obj = default(T);

            try
            {
                if (!_session.Transaction.IsActive)
                {
                    _session.BeginTransaction();
                    obj = (T)_session.Get<T>(id);
                    _session.Transaction.Commit();
                    _session.Flush();
                }
                else
                {
                    throw new Exception(CustomErrorMessage.TransactionAlreadyInProgress);
                }
            }
            catch (Exception)
            {
                _session.Transaction.Rollback();
                _session.Clear();

                throw;
            }

            return obj;
        }
... ... ... 
}

教师资源库.cs

public class TeacherRepository : Repository<Teacher>
    {
    }