Unable to cast object help!!

moorcroft · **Joined:** Tue Jul 28, 2009 8:28 am **Posts:** 18

Hi, could somebody please review my source and let me know where I am going wrong. I am trying to insert a new application record and am receiving an exception when I try session.Flush().

Here is the application mapping (have changed some values for display purposes):

Code:

<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"  assembly="..." namespace="...">
<class name="Application" table="APPLICATION">
   <id name="UniqueId" column="COUNTER">
      <generator class="sequence">
            <param name="sequence">MySQ</param>
      </generator>
   </id>   
   <property name="CreatedDate" column="CREATE_DATE"/>
   <property name="CreatedBy" column="CREATE_BY" type="AnsiString"/>
   ...
   <many-to-one name="ApplicationType" column="APPLICATION_CODE" class="ApplicationTypeCode" fetch="join" lazy="false" property-ref="CodeValue"/>
   <many-to-one name="ResultCode" column="RESULT_CODE" class="ApplicationResultCode" fetch="join" lazy="false" property-ref="CodeValue"/>
   <property name="ApplicationCost" column="COST" type="AnsiString"/>
</class>
</hibernate-mapping>

Here is the class for application:

Code:

using System;
using System.Collections.Generic;
using System.Text;

namespace ...
{
    public class Application: ICreation
    {
        private int? mUniqueID;

        public virtual int? UniqueId
        {
            get { return mUniqueID; }
            set { mUniqueID = value; }
        }
        
        private DateTime? createdDate;
        private string createdBy;

        public virtual string CreatedBy
        {
            get { return createdBy; }
            set { createdBy = value; }
        }

        public virtual DateTime? CreatedDate
        {
            get { return createdDate; }
            set { createdDate = value; }
        }

        private ApplicationTypeCode mApplicationType;

        public virtual ApplicationTypeCode ApplicationType
        {
            get { return mApplicationType; }
            set { mApplicationType = value; }
        }

        private ApplicationResultCode mResultCode;

        public virtual ApplicationResultCode ResultCode
        {
            get { return mResultCode; }
            set { mResultCode = value; }
        }

        private string mApplicationCost;

        /// <summary>
        /// Gets or sets the application cost, populated from the application type code
        /// </summary>
        /// <value>The application cost.</value>
        public virtual string ApplicationCost
        {
            get { return mApplicationCost; }
            set { mApplicationCost = value; }
        }
        
    }
}

Here is the class for ICreation:

Code:

namespace ...
{
    public interface ICreation
    {
        string CreatedBy
        {
            get;
            set;
        }

        Nullable<DateTime> CreatedDate
        {
            get;
            set;
        }
    }
}

Here is the mapping for codes:

Code:

<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"  assembly="..." namespace="...">
<class name="CodeListItem" table="CODES" discriminator-value="0">
<cache usage="read-only"/>
   <composite-id >
      <key-property name="CodeListId" column="APP_DATA_CODE"/>
      <key-property name="CodeValue" column="APP_CODE"/>
   </composite-id>
   <discriminator column="APP_DATA_CODE" type="Int32"/>
   <property name="CodeValue" column="APP_CODE" type="AnsiString"/>
   <property name="CodeDescription" column="CODE_DESC" type="AnsiString"/>   
   <property name="CodeListId" column="APP_DATA_CODE" type="AnsiString"/>
</class>
<subclass name="ApplicationTypeCode" discriminator-value="225" extends="CodeListItem">
<property name="CodeValue" column="APP_CODE" type="AnsiString"/>
<property name="ApplicationCost" column="PARENT_APP_CODE" type="AnsiString"/>
<property name="ValidFor" column="APP_TEXT" type="AnsiString"/>  
</subclass>
<subclass name="ApplicationResultCode" discriminator-value="325" extends="CodeListItem">
<property name="CodeValue" column="APP_CODE" type="AnsiString"/>
</subclass>
</hibernate-mapping>

Now the error I get when I try a session.Flush is the following:

Unable to cast object of type 'System.String' to type '........BusinessEntities.CodeListItem'

(replaced the namespaces etc with dots.

wolli · **Posted:** Wed Jan 13, 2010 5:13 am

I'm not sure, what exactly causes this, but at least I see some problems in your mapping. You have duplicate mappings for CodeValue, which probably causes the error. Why do you map the property separately ? The key should be enough.

moorcroft · **Joined:** Tue Jul 28, 2009 8:28 am **Posts:** 18

It is mapped again as the ApplicationTypeCode class is a subclass of CodeListItem and it extends it. This mapping file worked successfully in Visual Studio 2005 using the previous release of NHibernate (1.0.2 I think). We then upgraded to Visual Studio 2008 and NHibernate 1.2 and this is when we are getting the problem

wolli · **Posted:** Wed Jan 13, 2010 5:30 am

Try and remove the property mappings for CodeValue. In my opinion they are not necessary (except maybe the one in the base class for the property-ref). Is the CodeValue unique ? If not I wonder how the many-to-one is working at all.

moorcroft · **Joined:** Tue Jul 28, 2009 8:28 am **Posts:** 18

Hi thanks but that didn't work, am still getting the same error at session.Flush() using the following:

session.Save(application);
session.Flush();

moorcroft · **Joined:** Tue Jul 28, 2009 8:28 am **Posts:** 18

If I step into flush() it fails at the line:

public class ApplicationTypeCode: CodeListItem
{

/// <summary>
/// Gets or sets the code value.
/// </summary>
/// <value>The code value.</value>
public virtual new string CodeValue
{
get { return base.CodeValue; } <------
set { base.CodeValue = value; }
}

wolli · **Posted:** Wed Jan 13, 2010 8:26 am

Can you define a second property CodeValue2 (+ a mpping)which points to the same field and use that instead of CodeValue in the many-to-one mapping. I suspect that CodeValue also being part of the identiy definition causes your problem.

moorcroft · **Joined:** Tue Jul 28, 2009 8:28 am **Posts:** 18

Tried this and am still getting the same exception: Unable to cast object of type 'System.String' to type '........BusinessEntities.CodeListItem'.

wolli · **Posted:** Wed Jan 13, 2010 9:59 am

Sorry, I'm running out of ideas. You can try the google group and see if somebody there knows the answer:

http://groups.google.com/group/nhusers?hl=en