无法使用HQL通过外键从表中获取数据

Question

i have a class

public class HobbyHome:Establishment

{

public virtual ICollection<HobbyHomeAddress> HobbyHomeAddressList { set; get; }
public virtual ICollection<HobbyDeveloper> HobbyDeveloperList { set; get; }
public virtual ICollection<HobbyDetail> HobbyDetailList { set; get; }

}

inside the hobbyDetail:

  [Key]
    public virtual int HobbyDetailID { get; set; }


   // public virtual int HobbyId { get; set; }     
    public virtual HobbyMasters Hobbymaster { get; set; }
    public virtual Course course { get; set; }
    public virtual StudyMedium StudyMedium { get; set; }
    public virtual decimal Fees { get; set; }

}

ican save my data in both the tables...but while fetching hobbydetail through HobbyHomeId...i'm getting error as can not find Field

the mapping file for Hobbyhome:

<?xml version="1.0" encoding="utf-8" ?>

 <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly ="HobbyHomes"  namespace="HobbyHomes.Model" >
  <class name ="HobbyHome" table="HobbyHome">
   <id name="EstablishmentId" column="HobbyHomeId">
        <generator class="native"/>
   </id>
  <property name="Name"/>

  <set name="HobbyHomeAddressList">
        <key column="HobbyHomeId" foreign-key="fk_HobbyHomeAddress_HobbyHomeId"/>
      <one-to-many class ="HobbyHomes.Model.HobbyHomeAddress"/>
      </set>
      <set name="HobbyDeveloperList">
           <key column="HobbyHomeId" foreign-key="fk_HobbyDeveloper_HobbyHomeId"/>
           <one-to-many class ="HobbyHomes.Model.HobbyDeveloper"/>
   </set>
   <set name="HobbyDetailList">
       <key column="HobbyHomeId" foreign-key="fk_HobbyDetail_HobbyHomeId"/>
       <one-to-many class ="HobbyHomes.Model.HobbyDetail"/>
  </set>
 </class>
</hibernate-mapping>

here is my function for fetch the data:

  public HobbyDetail FetchbyHobbyId(int id)
    {
        log.Debug("Start");
        ISession session = DataAccessLayerHelper.OpenWriterSession();
        ITransaction transaction = session.BeginTransaction();
        HobbyDetail hobbydetail = null;
        try
        {

            ICriteria criteria = session.CreateCriteria(typeof(HobbyDetail))
               .Add(Restrictions.Eq("HobbyHomeId", id));

            hobbydetail = criteria.UniqueResult<HobbyDetail>();

            transaction.Commit();
        }
        catch (SessionException ex)
        {
            if (transaction != null && transaction.IsActive)
                transaction.Rollback();

            log.Error(ex);
            hobbydetail = null;
        }

        finally
        {
            if (transaction != null)
                transaction.Dispose();

            if (session != null && session.IsConnected)
                session.Close();

            log.Debug("End");
        }
        return hobbydetail;
    }

can sumbody please help me with this....

Answer 1

HQL is an object oriented query language. You can only use identifiers that exist in your class model.

You could add a back reference from the HobbyDetail to the HobbyHome making the reference bidirectional.

You could also use a subquery to get all the details that are in the list of the HobbyHome. This is easier with HQL than with criteria.

On the other hand it is much easier to just load the HobbyHome.

        ICriteria criteria = session.CreateCriteria(typeof(HobbyHome))
           .Add(Restrictions.IdEq(id));

        var home = criteria.UniqueResult<HobbyHome>();
        var details = home.HobbyDetailList;