Use of Expression with a many-to-many mapping

bosh · **Joined:** Fri Nov 04, 2005 12:37 pm **Posts:** 81

Hibernate version: 1.2.0 beta 1

Mapping documents:

Code:

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0">
  <class name="careers.core.domain.intdir.DirectoryEntry,careers.core" lazy="false"  table="idInternationalDirectory">

    <id name="Id" column="ID" type="Int32" unsaved-value="0">
      <generator class="native"/>
    </id>
    <many-to-one name="Client"    class="careers.core.domain.cems.Client,careers.core" column="ClientID"/>
    <many-to-one name="Location"    class="careers.core.domain.intdir.Location,careers.core" column="HESAID"/>
    <property column="Profile" type="String" name="Profile" not-null="true" length="2000" />
    <property column="url" type="String" name="Url" not-null="true" length="50" />

    <set name="Tows" lazy="false"  table="idTowLookup">
      <key column="entryID" />
      <many-to-many column="TOWID" class="careers.core.domain.intdir.Tow,careers.core" />
    </set>

  </class>

  <query name="DirectoryEntry.Search">from DirectoryEntry de where de.Client.ClientName like ? or de.Profile like ?</query>
  <query name="DirectoryEntry.SearchByName">from DirectoryEntry de where de.Client.ClientName like ?</query>
  <query name="DirectoryEntry.SearchByProfile">from DirectoryEntry de where de.Profile like ?</query>
  <query name="DirectoryEntry.S">from DirectoryEntry de where de.Client.ClientName like ? or de.Profile like ?</query>
  
</hibernate-mapping>

Code:

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0">
  <class name="careers.core.domain.intdir.Tow,careers.core" lazy="false" table="csTOW">
    <id name="Towid" column="TOWID" type="Int32" unsaved-value="0">
      <generator class="native"/>
    </id>
    <property column="TOW_desc" type="String" name="TowDesc" length="250" />
    <property column="bitcode" type="Int32" name="Bitcode" />
  </class>

  <query name="Two.GetAll">from Tow where Towid > 1 order by TOW_desc</query>
</hibernate-mapping>

I am having problems writing a query using the Expression class.

What i need to to return a list of 'DirectoryEntry' who have a relationship with a 'Tow' of a certain id. I dont understand how to query each Directory Entry's set of Tows?

batmat · **Posted:** Mon Dec 11, 2006 8:49 am

bosh wrote:

I am having problems writing a query using the Expression class.

What i need to to return a list of 'DirectoryEntry' who have a relationship with a 'Tow' of a certain id. I dont understand how to query each Directory Entry's set of Tows?

First, don't use Expression class, see its javadoc :

Code:

/**
 * This class is semi-deprecated. Use <tt>Restrictions</tt>.
 *
 * @see Restrictions
 * @author Gavin King
 */

So, use Restrictions instead.

Then, with HQL, you must "think" object. So, you should not use columns, but property names.

Your HQL query would look like :
<query name="Two.GetAll">from Tow t where t.Towid > 1 order by t.TowDesc</query>

Hey, I just noticed I'm in the NHibernate forum. Maybe what I just said is not completely true, I use Hibernate :-).