Need help with Hibernate? Read this first:
http://www.hibernate.org/ForumMailingli ... AskForHelp

I am using NHibernate, the HowToAskForHelp says to read the Quick Start -- which I have.

I have setup a very simple parent to child model. When I try to save the
first Parent, I get an Invalid Cast Exception. When I remove the <set> tag from the Parent schema, I don't get the error.[/quote]

Can anyone give me a suggestion as to the problem, or a technique to go
about troubleshooting this?

Many thanks,
Steve Brennan

Hibernate version: NHibernate 1.0.2

Mapping documents:
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0">
<class name="NHRepro.Parent, NHRepro" table="[Parent]">
<id name="ParentID" column="parent_id" type="int" unsaved-value="-1">
<generator class="native" />
</id>
<set name="Children">
<key column="parent_id" />
<one-to-many class="NHRepro.Child, NHRepro" />
</set>
</class>
</hibernate-mapping>

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0">
<class name="NHRepro.Child, NHRepro" table="[Child]">
<id name="ChildID" column="child_id" type="int" unsaved-value="-1">
<generator class="native" />
</id>
<many-to-one name="Parent" column="parent_id" not-null="true" />
</class>
</hibernate-mapping>


Code between sessionFactory.openSession() and session.close():
Parent p = new Parent();
session.Save(p); // BANG!!
session.Flush();


Full stack trace of any exception that occurs:
Could not save object
at NHibernate.Impl.SessionImpl.SaveWithGeneratedIdentifier(Object obj,
CascadingAction action, Object anything)
at NHibernate.Impl.SessionImpl.Save(Object obj)
at NHRepro.EntryPoint.Main() in c:\brennan\nhrepro\entrypoint.cs:line 26

Specified cast is not valid.
System.InvalidCastException: Specified cast is not valid.
at NHibernate.Type.SetType.Wrap(ISessionImplementor session, Object
collection)
at NHibernate.Impl.WrapVisitor.ProcessArrayOrNewCollection(Object
collection, PersistentCollectionType collectionType)
at NHibernate.Impl.WrapVisitor.ProcessCollection(Object collection,
PersistentCollectionType collectionType)
at NHibernate.Impl.AbstractVisitor.ProcessValue(Object value, IType type)
at NHibernate.Impl.WrapVisitor.ProcessValues(Object[] values, IType[] types)
at NHibernate.Impl.SessionImpl.DoSave(Object theObj, Key key,
IClassPersister persister, Boolean replicate, Boolean useIdentityColumn,
CascadingAction cascadeAction, Object anything)
at NHibernate.Impl.SessionImpl.DoSave(Object obj, Object id, IClassPersister
persister, Boolean useIdentityColumn, CascadingAction cascadeAction, Object
anything)
at NHibernate.Impl.SessionImpl.SaveWithGeneratedIdentifier(Object obj,
CascadingAction action, Object anything)The program '[3444] NHRepro.exe' has
exited with code 0 (0x0).


Name and version of the database you are using:
MS SQL Server 2000 SP3

The generated SQL (show_sql=true):
How/where to do I set this in NHibernate?
I have added the following to the nhibernate section of my config file:
<add key="hibernate.show_sql" value="true" />
I have not seen any new output and I don't know where to look.


Debug level Hibernate log excerpt:
281 [3764] INFO NHibernate.Cfg.Environment (null) - NHibernate 1.0.2
734 [3764] INFO NHibernate.Cfg.Environment (null) - Using reflection optimizer
734 [3764] INFO NHibernate.Cfg.Configuration (null) - Searching for mapped documents in assembly: NHRepro
750 [3764] INFO NHibernate.Cfg.Configuration (null) - Found mapping documents in assembly: NHRepro.Child.hbm.xml
812 [3764] INFO NHibernate.Dialect.Dialect (null) - Using dialect: NHibernate.Dialect.MsSql2000Dialect
843 [3764] INFO NHibernate.Cfg.Binder (null) - Mapping class: NHRepro.Child -> [Child]
859 [3764] DEBUG NHibernate.Cfg.Binder (null) - Mapped property: ChildID -> child_id, type: Int32
890 [3764] DEBUG NHibernate.Cfg.Binder (null) - Mapped property: Parent -> parent_id, type: Parent
890 [3764] INFO NHibernate.Cfg.Configuration (null) - Found mapping documents in assembly: NHRepro.Parent.hbm.xml
890 [3764] INFO NHibernate.Dialect.Dialect (null) - Using dialect: NHibernate.Dialect.MsSql2000Dialect
890 [3764] INFO NHibernate.Cfg.Binder (null) - Mapping class: NHRepro.Parent -> [Parent]
890 [3764] DEBUG NHibernate.Cfg.Binder (null) - Mapped property: ParentID -> parent_id, type: Int32
906 [3764] DEBUG NHibernate.Cfg.Binder (null) - Mapped property: Children, type: ISet
906 [3764] INFO NHibernate.Cfg.Configuration (null) - processing one-to-many association mappings
906 [3764] DEBUG NHibernate.Cfg.Binder (null) - Second pass for collection: NHRepro.Parent.Children
906 [3764] INFO NHibernate.Cfg.Binder (null) - mapping collection: NHRepro.Parent.Children -> [Child]
921 [3764] DEBUG NHibernate.Cfg.Binder (null) - Mapped collection key: parent_id, one-to-many: Child
921 [3764] INFO NHibernate.Cfg.Configuration (null) - processing one-to-one association property references
921 [3764] INFO NHibernate.Cfg.Configuration (null) - processing foreign key constraints
921 [3764] DEBUG NHibernate.Cfg.Configuration (null) - resolving reference to class: Parent
921 [3764] INFO NHibernate.Dialect.Dialect (null) - Using dialect: NHibernate.Dialect.MsSql2000Dialect
921 [3764] INFO NHibernate.Cfg.SettingsFactory (null) - use outer join fetching: True
921 [3764] INFO NHibernate.Connection.ConnectionProviderFactory (null) - Intitializing connection provider: NHibernate.Connection.DriverConnectionProvider
921 [3764] INFO NHibernate.Connection.ConnectionProvider (null) - Configuring ConnectionProvider
937 [3764] INFO NHibernate.Cfg.SettingsFactory (null) - Optimize cache for minimal puts: False
937 [3764] INFO NHibernate.Cfg.SettingsFactory (null) - Query language substitutions: {}
937 [3764] INFO NHibernate.Cfg.SettingsFactory (null) - cache provider: NHibernate.Cache.HashtableCacheProvider
937 [3764] INFO NHibernate.Cfg.Configuration (null) - instantiating and configuring caches
937 [3764] INFO NHibernate.Impl.SessionFactoryImpl (null) - building session factory
937 [3764] DEBUG NHibernate.Impl.SessionFactoryImpl (null) - instantiating session factory with properties: {hibernate.dialect=NHibernate.Dialect.MsSql2000Dialect, hibernate.use_reflection_optimizer=True, hibernate.connection.connection_string=Server=localhost;initial catalog=NHRepro;User ID=OneThroughSix; Password=123456, hibernate.connection.provider=NHibernate.Connection.DriverConnectionProvider, hibernate.connection.driver_class=NHibernate.Driver.SqlClientDriver}
984 [3764] DEBUG NHibernate.Persister.GetSetHelperFactory (null) - Init compiler for class NHRepro.Child
984 [3764] DEBUG NHibernate.Persister.GetSetHelperFactory (null) - Adding referenced assembly c:\brennan\nhrepro\bin\debug\nhibernate.dll
984 [3764] DEBUG NHibernate.Persister.GetSetHelperFactory (null) - Adding referenced assembly C:\brennan\NHRepro\bin\Debug\NHRepro.exe
984 [3764] DEBUG NHibernate.Persister.GetSetHelperFactory (null) - Adding referenced assembly c:\windows\microsoft.net\framework\v1.1.4322\mscorlib.dll
984 [3764] DEBUG NHibernate.Persister.GetSetHelperFactory (null) - Adding referenced assembly c:\brennan\nhrepro\bin\debug\log4net.dll
984 [3764] DEBUG NHibernate.Persister.GetSetHelperFactory (null) - Adding referenced assembly c:\windows\assembly\gac\system\1.0.5000.0__b77a5c561934e089\system.dll
1203 [3764] DEBUG NHibernate.Persister.GetSetHelperFactory (null) - Compiled ok:
using System;
using NHibernate.Property;
namespace NHibernate.Persister {
public class GetSetHelper_NHRepro_Child : IGetSetHelper {
ISetter[] setters;
IGetter[] getters;
public GetSetHelper_NHRepro_Child(ISetter[] setters, IGetter[] getters) {
this.setters = setters;
this.getters = getters;
}
public void SetPropertyValues(object obj, object[] values) {
NHRepro.Child t = (NHRepro.Child)obj;
try
{
t.Parent = (NHRepro.Parent)values[0];
}
catch( InvalidCastException ice )
{
throw new MappingException(
"Invalid mapping information specified for type " + obj.GetType() + ", check your mapping file for property type mismatches",
ice);
}
}
public object[] GetPropertyValues(object obj) {
NHRepro.Child t = (NHRepro.Child)obj;
object[] ret = new object[1];
ret[0] = t.Parent;
return ret;
}
}
}

1218 [3764] DEBUG NHibernate.Persister.GetSetHelperFactory (null) - Init compiler for class NHRepro.Parent
1218 [3764] DEBUG NHibernate.Persister.GetSetHelperFactory (null) - Adding referenced assembly c:\brennan\nhrepro\bin\debug\nhibernate.dll
1218 [3764] DEBUG NHibernate.Persister.GetSetHelperFactory (null) - Adding referenced assembly C:\brennan\NHRepro\bin\Debug\NHRepro.exe
1218 [3764] DEBUG NHibernate.Persister.GetSetHelperFactory (null) - Adding referenced assembly c:\windows\microsoft.net\framework\v1.1.4322\mscorlib.dll
1218 [3764] DEBUG NHibernate.Persister.GetSetHelperFactory (null) - Adding referenced assembly c:\brennan\nhrepro\bin\debug\log4net.dll
1218 [3764] DEBUG NHibernate.Persister.GetSetHelperFactory (null) - Adding referenced assembly c:\windows\assembly\gac\system\1.0.5000.0__b77a5c561934e089\system.dll
1421 [3764] DEBUG NHibernate.Persister.GetSetHelperFactory (null) - Compiled ok:
using System;
using NHibernate.Property;
namespace NHibernate.Persister {
public class GetSetHelper_NHRepro_Parent : IGetSetHelper {
ISetter[] setters;
IGetter[] getters;
public GetSetHelper_NHRepro_Parent(ISetter[] setters, IGetter[] getters) {
this.setters = setters;
this.getters = getters;
}
public void SetPropertyValues(object obj, object[] values) {
NHRepro.Parent t = (NHRepro.Parent)obj;
try
{
t.Children = (System.Collections.IList)values[0];
}
catch( InvalidCastException ice )
{
throw new MappingException(
"Invalid mapping information specified for type " + obj.GetType() + ", check your mapping file for property type mismatches",
ice);
}
}
public object[] GetPropertyValues(object obj) {
NHRepro.Parent t = (NHRepro.Parent)obj;
object[] ret = new object[1];
ret[0] = t.Children;
return ret;
}
}
}

1515 [3764] DEBUG NHibernate.Impl.SessionFactoryObjectFactory (null) - initializing class SessionFactoryObjectFactory
1515 [3764] DEBUG NHibernate.Impl.SessionFactoryObjectFactory (null) - registered: 4adfc94f11ce472b819530cea231566a(unnamed)
1515 [3764] INFO NHibernate.Impl.SessionFactoryObjectFactory (null) - no name configured
1515 [3764] DEBUG NHibernate.Impl.SessionFactoryImpl (null) - Instantiated session factory
1531 [3764] DEBUG NHibernate.Impl.SessionImpl (null) - opened session
1531 [3764] DEBUG NHibernate.Impl.SessionImpl (null) - saving [NHRepro.Parent#<null>]
1531 [3764] DEBUG NHibernate.Impl.SessionImpl (null) - executing insertions
1546 [3764] DEBUG NHibernate.Util.ADOExceptionReporter (null) - Could not save object
System.InvalidCastException: Specified cast is not valid.
at NHibernate.Type.SetType.Wrap(ISessionImplementor session, Object collection)
at NHibernate.Impl.WrapVisitor.ProcessArrayOrNewCollection(Object collection, PersistentCollectionType collectionType)
at NHibernate.Impl.WrapVisitor.ProcessCollection(Object collection, PersistentCollectionType collectionType)
at NHibernate.Impl.AbstractVisitor.ProcessValue(Object value, IType type)
at NHibernate.Impl.WrapVisitor.ProcessValues(Object[] values, IType[] types)
at NHibernate.Impl.SessionImpl.DoSave(Object theObj, Key key, IClassPersister persister, Boolean replicate, Boolean useIdentityColumn, CascadingAction cascadeAction, Object anything)
at NHibernate.Impl.SessionImpl.DoSave(Object obj, Object id, IClassPersister persister, Boolean useIdentityColumn, CascadingAction cascadeAction, Object anything)
at NHibernate.Impl.SessionImpl.SaveWithGeneratedIdentifier(Object obj, CascadingAction action, Object anything)
1562 [3764] WARN NHibernate.Util.ADOExceptionReporter (null) - System.InvalidCastException: Specified cast is not valid.
at NHibernate.Type.SetType.Wrap(ISessionImplementor session, Object collection)
at NHibernate.Impl.WrapVisitor.ProcessArrayOrNewCollection(Object collection, PersistentCollectionType collectionType)
at NHibernate.Impl.WrapVisitor.ProcessCollection(Object collection, PersistentCollectionType collectionType)
at NHibernate.Impl.AbstractVisitor.ProcessValue(Object value, IType type)
at NHibernate.Impl.WrapVisitor.ProcessValues(Object[] values, IType[] types)
at NHibernate.Impl.SessionImpl.DoSave(Object theObj, Key key, IClassPersister persister, Boolean replicate, Boolean useIdentityColumn, CascadingAction cascadeAction, Object anything)
at NHibernate.Impl.SessionImpl.DoSave(Object obj, Object id, IClassPersister persister, Boolean useIdentityColumn, CascadingAction cascadeAction, Object anything)
at NHibernate.Impl.SessionImpl.SaveWithGeneratedIdentifier(Object obj, CascadingAction action, Object anything)
1562 [3764] ERROR NHibernate.Util.ADOExceptionReporter (null) - Specified cast is not valid.

I used Profiler to catch the SQL generated by my repro app.

exec sp_reset_connection
exec sp_reset_connection
INSERT INTO [Parent] DEFAULT VALUES; select SCOPE_IDENTITY()

INSERT INTO [Parent] DEFAULT VALUES;


INSERT INTO [Parent] DEFAULT VALUES;
select SCOPE_IDENTITY()
select SCOPE_IDENTITY()
INSERT INTO [Parent] DEFAULT VALUES; select SCOPE_IDENTITY()

I don't know how to close a thread, but I am no longer getting the exception, I was missing a class attribute on the many-to-one element.

Thanks,
Steve Brennan