Many-to-one relation problem

Samuel · **Joined:** Mon Jan 15, 2007 10:09 am **Posts:** 12

hi all!

I just want to know if by using a many-to-one relation, i could have the parent element. To explain my question, i have a Class Group and a Class Customer which mapping files are :

Groupe:

Code:

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" namespace="ArchivecoFramework" assembly="ArchivecoFramework">
  <class name="Groupe" table="V_GROUPE">
    <id name="NomGroupe">
      <column name="GROUPE"/>
      <generator class="assigned"/>
    </id>
    <set name="Clients" inverse="true" lazy="true">
      <key column="GROUPE"/>
      <one-to-many class="Client"/>
    </set>
  </class>
</hibernate-mapping>

Client :

Code:

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" namespace="ArchivecoFramework" assembly="ArchivecoFramework">
  <class name="Client" table="FCLIENTREF">
    
    <id name="CodeClient">
      <column name="CODECLIENT" not-null="true"/>
      <generator class="assigned"/>
    </id>

    <property name="NomClient" column="NOMCLIENT" not-null="true"/>
    <property name="Actif" column="INACTIF" type="boolean"/>
    <property name="IpAutorisees" column="IPAUTORISEES" type="String"/>
    <property name="Ssl" column="SSL" type="boolean"/>

    <!--<property name="Groupe" column="GROUPE" not-null="true"/>-->

    <many-to-one name="GroupeParent" class="Groupe">
      <column name="GROUPE" not-null="true"/>
    </many-to-one>
    
    <bag name="Services" lazy="true">
      <key column="CODECLIENT"/>
      <one-to-many class="Service"/>
    </bag>
    
  </class>
</hibernate-mapping>

If i try to edit a HQL Query like

"IQuery query = session.CreateQuery("from Client");
comboBox1.DataSource = query.List();"

i just have an error message like "can't create a proxy instance".

Details :
"Creating a proxy instance failed
System.TypeLoadException: Access denied : 'ArchivecoFramework.Groupe'."

Can someone help me to resolve it ???

thx.

samueljob · **Joined:** Mon Jan 08, 2007 11:59 pm **Posts:** 31

Are you sure you have set all the properties in the class as virtual. This is needed for the lazy loading to work.

Job Samuel

gert · **Joined:** Thu Jan 19, 2006 4:29 pm **Posts:** 348

Samuel wrote:

Details :
"Creating a proxy instance failed
System.TypeLoadException: Access denied : 'ArchivecoFramework.Groupe'."

How is Your class declared? For lazy loading to work, the class must be public and not sealed.

Gert

Samuel · **Joined:** Mon Jan 15, 2007 10:09 am **Posts:** 12

Thank you for your answer but i verify it thousand times and it' s not the problem. If you want some details to help me you can just ask me, i will reply quickly.

Samuel · **Joined:** Mon Jan 15, 2007 10:09 am **Posts:** 12

Thank you gert you were right. It was a problem with my class declaration. I forgot to put it public and let it with default settings (internal).

mosi · **Joined:** Fri Sep 28, 2007 4:12 am **Posts:** 15

This might be a bit of a thread resurrection but I'd like to add a little to the confusion.
I was getting the same Exception like Samuel on a ICriteria.List<some.type> call as soon as I had some many-to-one mapping in that particular mapping file in NHibernate 1.2.
All of the mapped classes were default internal and making them public fixed the Exception "Creating a proxy instance failed" with an inner exception message of "Access is denied: 'some.namespace.Reader'.":"" where this Reader was the class that was referenced to by the many-to-one relation.

Maybe someone can shed a little light on this one. For now I'm going on with the mapped objects declared as public because of .. well... "because of don't" :)

karlchu · **Posted:** Fri Sep 28, 2007 9:32 am

An "internal" class means nothing outside of the assembly has access to it. NHibernate, being obviously an assembly on its own, has no access to an internal class in a different assembly. Therefore, NH cannot create a proxy base on that class

mosi · **Joined:** Fri Sep 28, 2007 4:12 am **Posts:** 15

Somehow it seems pretty obvious when I think about it a second time. I guess I should file this under "there is no magic" since accessing internal classes from outside the assembly clearly would require a lot of magic.
Thanks for clearing that one up!