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NVS
 Post subject: Need help with joined-subclass and polymorphic association
PostPosted: Fri Jul 29, 2005 12:06 pm 
Newbie

Joined: Fri Jul 29, 2005 11:48 am
Posts: 11
My mapping file is below. I created a joined-subclass and in the subclass I added a polymorphic association back to the parent class, just like it's described in the Hibernate documentation.

When I try to create a child object and associated it back to a parent and save it :
Code:
Owner owner = GetOwnerFromRequest();
Investor investor = new Investor();
investor.Owner = owner;
Save(investor);


I get this error:
Quote:
System.Data.SqlClient.SqlException: Column name 'InvestorId' appears more than once in the result column list.


I still don't fully understand subclass and polymorphic associations in Hibernate yet. Can you guys offer some suggestions or directions? Thanks.

Code:
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0">
   <class name="Owner" table="Owner">
      <id name="Id" column="OwnerId" type="Guid" unsaved-value="00000000-0000-0000-0000-000000000000">
         <generator class="guid"/>
      </id>
      <property column="Prefix" type="String" name="Prefix" length="10" />
      <property column="FirstName" type="String" name="FirstName" length="50" />
      <property column="MiddleInitial" type="String" name="MiddleInitial" length="10" />
      <property column="LastName" type="String" name="LastName" length="50" />
      <property column="Salutation" type="String" name="Salutation" length="50" />
      <property column="Title" type="String" name="Title" length="50" />
      <property column="Company" type="String" name="Company" length="50" />
      <property column="WorkPhone1" type="String" name="WorkPhone1" length="50" />
      <property column="WorkPhone2" type="String" name="WorkPhone2" length="50" />
      <property column="HomePhone1" type="String" name="HomePhone1" length="50" />
      <property column="HomePhone2" type="String" name="HomePhone2" length="50" />
      <property column="CellPhone" type="String" name="CellPhone" length="50" />
      <property column="Fax" type="String" name="Fax" length="50" />
      <property column="Email" type="String" name="Email" length="50" />
      <property column="DoNotCall" type="Nullables.NHibernate.NullableBooleanType, Nullables.NHibernate" name="DoNotCall" />
      <property column="DoNotMail" type="Nullables.NHibernate.NullableBooleanType, Nullables.NHibernate" name="DoNotMail" />
      <property column="DoNotEmail" type="Nullables.NHibernate.NullableBooleanType, Nullables.NHibernate" name="DoNotEmail" />
      <property column="DoNotFax" type="Nullables.NHibernate.NullableBooleanType, Nullables.NHibernate" name="DoNotFax" />
      <property column="Reports" type="String" name="Reports" length="50" />
      
      <bag name="Properties" lazy="true" table="PropertyOwned" cascade="all" inverse="true">
         <key column="OwnerId" />
         <composite-element class="PropertyOwned">
            <parent name="Owner" />
            <property column="IsPrimaryOwner" type="Nullables.NHibernate.NullableBooleanType, Nullables.NHibernate" name="IsPrimaryOwner" />
            <property column="FromDate" type="Nullables.NHibernate.NullableDateTimeType, Nullables.NHibernate" name="FromDate" />
            <property column="ToDate" type="Nullables.NHibernate.NullableDateTimeType, Nullables.NHibernate" name="ToDate" />
            <property column="OwnerType" type="String" name="OwnerType" length="50" />
            <property column="NameOnFile" type="String" name="NameOnFile" length="50" />
            <many-to-one name="Property" column="PropertyId" class="Property" />
         </composite-element>
      </bag>
            
      <many-to-one name="CreatedBy" class="User" column="CreatedBy" />
      <property column="CreateDate" type="Nullables.NHibernate.NullableDateTimeType, Nullables.NHibernate" name="CreateDate" />
      <many-to-one name="UpdatedBy" class="User" column="UpdatedBy" />
      <property column="UpdateDate" type="Nullables.NHibernate.NullableDateTimeType, Nullables.NHibernate" name="UpdateDate" />
      
      <joined-subclass name="Investor" table="Investor">
         <key column="InvestorId" />
         <many-to-one name="Owner" column="InvestorId" class="Owner" />
         <property name="Type" column="InvestorType" type="String" length="50" />
         <bag name="Offers" lazy="true" inverse="true">
            <key column="InvestorId" />
            <one-to-many class="Offer" />
         </bag>
      </joined-subclass>
   </class>
</hibernate-mapping>
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sergey
 Post subject:
PostPosted: Fri Jul 29, 2005 5:32 pm 
Contributor
Contributor

Joined: Wed May 11, 2005 4:59 pm
Posts: 1766
Location: Prague, Czech Republic
You have two different properties mapped to the InvestorId column, looks like it's your problem:
Code:
      <joined-subclass name="Investor" table="Investor">
         <key column="InvestorId" />
         <many-to-one name="Owner" column="InvestorId" class="Owner" />
         ...
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NVS
 Post subject:
PostPosted: Fri Jul 29, 2005 6:00 pm 
Newbie

Joined: Fri Jul 29, 2005 11:48 am
Posts: 11
the second property:
Code:
<many-to-one name="Owner" column="InvestorId" class="Owner" />


Is for the association back to the parent object, and its in the Hibernate documentation http://www.hibernate.org/hib_docs/reference/en/html/inheritance.html.

Otherwise how can i create a row in the subclass table and associate its PKFK back to the row in the parent class table?

I kind of came up with a work around, by creating another class and adding a one-to-one mapping between the new class and my parent class. The mapping file is below:
Code:
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0">
   <class name="OwnerInvestor" table="Investor">
      <id name="Id" column="InvestorId" type="Guid" unsaved-value="00000000-0000-0000-0000-000000000000">
         <generator class="foreign">
            <param name="property">Owner</param>
         </generator>
      </id>
      <one-to-one name="Owner" class="Owner" constrained="true" />
   </class>
</hibernate-mapping>


Now if I do:
Code:
OwnerInvestor ownerInvestor = new OwnerInvestor();
ownerInvestor.Owner = owner;
Save(ownerInvestor);

I just created my association back to my parent object. Its very messy though.

Theretically, now I can retreive my Investor object like normal, but I'm getting this error:
Quote:
(loading object was of wrong class)

which is probably a totally different error all together.
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Guest
 Post subject:
PostPosted: Tue Aug 02, 2005 4:08 pm 
The documentation I was looking at was for Hibernate 2.1, and I could not find a reference to it in the 2.0.3 documentation. So it looks like its a feature that has not been added to NHibernate yet. But luckly joined-subclass is virtually the same as an one-to-one PKFK relation between 2 tables, so my work around works.

I'm experiencing another problem though. If I query for a subclass after i already queried for the parent class in the same session, it will always return the parent class. Is there anyway around this?
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