Question

I am looking for the best way to map from an XDocument property type to an Oracle XMLType? I am mapping to a legacy database and have no control over the schema. It is Oracle 9i.

I have read that version 3 of nHibernate provides out the box functionality for this type of mapping. I am using version 3.1 with fluent mappings and I receive the following error when using the default map on a create:

System.ArgumentOutOfRangeException : Specified argument was out of the range of valid values.
at Oracle.DataAccess.Client.OracleParameter.set_DbType(DbType value)
at NHibernate.Driver.DriverBase.SetCommandParameters(IDbCommand cmd, SqlType[] sqlTypes) in d:\CSharp\NH\NH\nhibernate\src\NHibernate\Driver\DriverBase.cs: line 180
at NHibernate.Driver.DriverBase.GenerateCommand(CommandType type, SqlString sqlString, SqlType[] parameterTypes) in d:\CSharp\NH\NH\nhibernate\src\NHibernate\Driver\DriverBase.cs: line 136
at NHibernate.AdoNet.AbstractBatcher.Generate(CommandType type, SqlString sqlString, SqlType[] parameterTypes) in d:\CSharp\NH\NH\nhibernate\src\NHibernate\AdoNet\AbstractBatcher.cs: line 78
at NHibernate.AdoNet.AbstractBatcher.PrepareBatchCommand(CommandType type, SqlString sql, SqlType[] parameterTypes) in d:\CSharp\NH\NH\nhibernate\src\NHibernate\AdoNet\AbstractBatcher.cs: line 146
at NHibernate.Persister.Entity.AbstractEntityPersister.Insert(Object id, Object[] fields, Boolean[] notNull, Int32 j, SqlCommandInfo sql, Object obj, ISessionImplementor session) in d:\CSharp\NH\NH\nhibernate\src\NHibernate\Persister\Entity\AbstractEntityPersister.cs: line 2616
at NHibernate.Persister.Entity.AbstractEntityPersister.Insert(Object id, Object[] fields, Object obj, ISessionImplementor session) in d:\CSharp\NH\NH\nhibernate\src\NHibernate\Persister\Entity\AbstractEntityPersister.cs: line 3050
at NHibernate.Action.EntityInsertAction.Execute() in d:\CSharp\NH\NH\nhibernate\src\NHibernate\Action\EntityInsertAction.cs: line 59
at NHibernate.Engine.ActionQueue.Execute(IExecutable executable) in d:\CSharp\NH\NH\nhibernate\src\NHibernate\Engine\ActionQueue.cs: line 136
at NHibernate.Engine.ActionQueue.ExecuteActions(IList list) in d:\CSharp\NH\NH\nhibernate\src\NHibernate\Engine\ActionQueue.cs: line 125
at NHibernate.Engine.ActionQueue.ExecuteActions() in d:\CSharp\NH\NH\nhibernate\src\NHibernate\Engine\ActionQueue.cs: line 170
at NHibernate.Event.Default.AbstractFlushingEventListener.PerformExecutions(IEventSource session) in d:\CSharp\NH\NH\nhibernate\src\NHibernate\Event\Default\AbstractFlushingEventListener.cs: line 241
at NHibernate.Event.Default.DefaultFlushEventListener.OnFlush(FlushEvent event) in d:\CSharp\NH\NH\nhibernate\src\NHibernate\Event\Default\DefaultFlushEventListener.cs: line 20
at NHibernate.Impl.SessionImpl.Flush() in d:\CSharp\NH\NH\nhibernate\src\NHibernate\Impl\SessionImpl.cs: line 1470

I got round this my writing my own user type which converts between an XDocument and a string:

public SqlType[] SqlTypes
{
get { return (new SqlType[] { new StringClobSqlType() }); }
}

public Type ReturnedType
{
get { return (typeof(XDocument)); }
}

public object NullSafeGet(IDataReader rs, string[] names, object owner)
{
XDocument xDoc = null;

int columnIndex = rs.GetOrdinal(names[0]);
if (!rs.IsDBNull(columnIndex))
{
xDoc = XDocument.Parse((rs[columnIndex].ToString()));
}

return (xDoc);
}

public void NullSafeSet(IDbCommand cmd, object value, int index)
{
IDbDataParameter parameter = (IDbDataParameter)cmd.Parameters[index];

if (value == null)
{
parameter.Value = DBNull.Value;
}
else
{
XDocument xDoc = (XDocument)value;
parameter.Value = xDoc.ConvertToString();

}
}

This worked fine until the string was greater than 4000 characters in length. Now I get the error:

NHibernate.Exceptions.GenericADOException : could not insert: [XmlBlob#95586][SQL: INSERT INTO XMLBLOB (CAT_CODE, BLB_BLOB, BLB_ID) VALUES (?, ?, ?)]
—-> Oracle.DataAccess.Client.OracleException : ORA-01461: can bind a LONG value only for insert into a LONG column

Answer 1

The only update I needed to be able to save more than 4000 characters to the XMLType column was to set the parameter type as OracleDbType.XmlType in the set method for my user type implementation:

    public void NullSafeSet(IDbCommand cmd, object value, int index)
    {
        IDbDataParameter parameter = (IDbDataParameter)cmd.Parameters[index];
       ((OracleParameter)parameter).OracleDbTypeEx = OracleDbType.XmlType;

        if (value == null)
        {
            parameter.Value = DBNull.Value;
        }
        else
        {
            XDocument xDoc = (XDocument)value;
            parameter.Value = xDoc.ConvertToString();
        }
    }