Using .NET Nullable Types with NHibernate 1.2

Originally, NHibernate 1.2 does not support nullable types from .NET such as DateTime?, int?, bool?, etc. but that can be solved by implementing specific NHibernate specific user types.
Not all nullable user types are listed for all .NET nullable types are listed below. But it can be easily done by following the example specially for numeric types.
However if you need help you jut send an email.

Nullable user types code listings:

NullableDateTimeType.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using NHibernate.UserTypes;
using NHibernate;
using System.Data;
using NHibernate.SqlTypes;

namespace Utilitario.GerenciaDados
{
  public class NullableDateTimeType : IUserType
  {
      #region IUserType Members
      public bool Equals(object x, object y)
      {
          return object.Equals(x, y);
      }
      public int GetHashCode(object x)
      {
          return x.GetHashCode();
      }
      public object NullSafeGet(IDataReader rs, string[] names, object owner)
      {
          //object valor = NHibernateUtil.DateTime.NullSafeGet(rs, names[0]);
          object valor = null;
          if (rs[names[0]] != DBNull.Value)
              valor = Convert.ToDateTime(rs[names[0]]);

          DateTime? dateTime = null;

          if (valor != null)
          {
              dateTime = (DateTime)valor;
          }
          return dateTime;
      }
      public void NullSafeSet(IDbCommand cmd, object value, int index)
      {
          if (value == null)
          {
              NHibernateUtil.String.NullSafeSet(cmd, null, index);
          }
          else
          {
              DateTime? dateTime = (DateTime)value;
              NHibernateUtil.AnsiString.NullSafeSet(cmd, dateTime.Value.ToString("yyyy/MM/dd HH:mm:ss.fff"), index);
          }
      }
      public object DeepCopy(object value)
      {
          return value;
      }
      public object Replace(object original, object target, object owner)
      {
          return original;
      }
      public object Assemble(object cached, object owner)
      {
          return cached;
      }
      public object Disassemble(object value)
      {
          return value;
      }
      public SqlType[] SqlTypes
      {
          get { return new SqlType[] { new StringSqlType() }; }
      }
      public Type ReturnedType
      {
          get { return typeof(string); }
      }
      public bool IsMutable
      {
          get { return false; }
      }
      #endregion
  }
}

NullableBooleanType.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using NHibernate.UserTypes;
using NHibernate;
using System.Data;
using NHibernate.SqlTypes;

namespace Utilitario.GerenciaDados
{
  public class NullableBooleanType : IUserType
  {
      #region IUserType Members
      public bool Equals(object x, object y)
      {
          return object.Equals(x, y);
      }
      public int GetHashCode(object x)
      {
          return x.GetHashCode();
      }
      public object NullSafeGet(IDataReader rs, string[] names, object owner)
      {
          object valor = NHibernateUtil.Boolean.NullSafeGet(rs, names[0]);
          bool? caracter = null;
          if (valor != null)
          {
              caracter = (bool)valor;
          }
          return caracter;
      }
      public void NullSafeSet(IDbCommand cmd, object value, int index)
      {
          if (value == null)
          {
              NHibernateUtil.Boolean.NullSafeSet(cmd, null, index);
          }
          else
          {
              bool? caracter = (bool)value;
              NHibernateUtil.Boolean.NullSafeSet(cmd, caracter.Value, index);
          }
      }
      public object DeepCopy(object value)
      {
          return value;
      }
      public object Replace(object original, object target, object owner)
      {
          return original;
      }
      public object Assemble(object cached, object owner)
      {
          return cached;
      }
      public object Disassemble(object value)
      {
          return value;
      }
      public SqlType[] SqlTypes
      {
          get { return new SqlType[] { new StringSqlType() }; }
      }
      public Type ReturnedType
      {
          get { return typeof(string); }
      }
      public bool IsMutable
      {
          get { return false; }
      }
      #endregion
  }
}

NullableCharType.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using NHibernate.UserTypes;
using NHibernate;
using System.Data;
using NHibernate.SqlTypes;

namespace Utilitario.GerenciaDados
{
  public class NullableCharType : IUserType
  {
      #region IUserType Members
      public bool Equals(object x, object y)
      {
          return object.Equals(x, y);
      }
      public int GetHashCode(object x)
      {
          return x.GetHashCode();
      }
      public object NullSafeGet(IDataReader rs, string[] names, object owner)
      {
          object valor = NHibernateUtil.Character.NullSafeGet(rs, names[0]);
          Char? caracter = null;
          if (valor != null)
          {
              caracter = (Char)valor;
          }
         return caracter;
      }
      public void NullSafeSet(IDbCommand cmd, object value, int index)
      {  
          if (value == null)
          {
               NHibernateUtil.Character.NullSafeSet(cmd, null, index);
          }
          else
          {
              Char? caracter = (Char)value;
              NHibernateUtil.Character.NullSafeSet(cmd, caracter.Value, index);
          }
      }
      public object DeepCopy(object value)
      {
          return value;
      }
      public object Replace(object original, object target, object owner)
      {
          return original;
      }
      public object Assemble(object cached, object owner)
      {
          return cached;
      }
      public object Disassemble(object value)
      {
          return value;
      }
      public SqlType[] SqlTypes
      {
          get { return new SqlType[] { new StringSqlType() }; }
      }
      public Type ReturnedType
      {
          get { return typeof(string); }
      }
      public bool IsMutable
      {
          get { return false; }
      }
      #endregion
  }
}

NullableDecimalType.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using NHibernate.UserTypes;
using System.Data;
using NHibernate.Util;
using NHibernate;
using NHibernate.SqlTypes;

namespace Utilitario.GerenciaDados
{
  public class NullableDecimalType : IUserType
  {
      #region IUserType Members
      public bool Equals(object x, object y)
      {
          return object.Equals(x, y);
      }
      public int GetHashCode(object x)
      {
          return x.GetHashCode();
      }
      public object NullSafeGet(IDataReader rs, string[] names, object owner)
      {
          object valor = NHibernateUtil.Decimal.NullSafeGet(rs, names[0]);
          Decimal? inteiro = null;
          if (valor != null)
          {
              inteiro = (Decimal)valor;
          }
          return inteiro;
      }
      public void NullSafeSet(IDbCommand cmd, object value, int index)
      {
          if (value == null)
          {
              NHibernateUtil.Decimal.NullSafeSet(cmd, null, index);
          }
          else
          {
              Decimal? inteiro = (Decimal)value;
              NHibernateUtil.Decimal.NullSafeSet(cmd, inteiro.Value.ToString().Replace(',','.'), index);
          }
      }
      public object DeepCopy(object value)
      {
          return value;
      }
      public object Replace(object original, object target, object owner)
      {
          return original;
      }
      public object Assemble(object cached, object owner)
      {
          return cached;
      }
      public object Disassemble(object value)
      {
          return value;
      }
      public SqlType[] SqlTypes
      {
          get { return new SqlType[] { new StringSqlType() }; }
      }
      public Type ReturnedType
      {
          get { return typeof(string); }
      }
      public bool IsMutable
      {
          get { return false; }
      }
      #endregion
  }
}

NullableDoubleType.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using NHibernate.UserTypes;
using NHibernate;
using NHibernate.SqlTypes;
using System.Data;

namespace Utilitario.GerenciaDados
{
  public class NullableDoubleType : IUserType
  {
      #region IUserType Members
      public bool Equals(object x, object y)
      {
          return object.Equals(x, y);
      }
      public int GetHashCode(object x)
      {
          return x.GetHashCode();
      }
      public object NullSafeGet(IDataReader rs, string[] names, object owner)
      {
          object valor = NHibernateUtil.Double.NullSafeGet(rs, names[0]);
          Double? valorD = null;
          if (valor != null)
          {
              valorD = (double)valor;
          }
          return valorD;
      }
      public void NullSafeSet(IDbCommand cmd, object value, int index)
      {
          if (value == null)
          {
              NHibernateUtil.Double.NullSafeSet(cmd, null, index);
          }
          else
          {
              Double? valor = (Double)value;
              NHibernateUtil.Double.NullSafeSet(cmd, valor.Value.ToString().Replace(',','.'), index);
          }
      }
      public object DeepCopy(object value)
      {
          return value;
      }
      public object Replace(object original, object target, object owner)
      {
          return original;
      }
      public object Assemble(object cached, object owner)
      {
          return cached;
      }
      public object Disassemble(object value)
      {
          return value;
      }
      public SqlType[] SqlTypes
      {
          get { return new SqlType[] { new StringSqlType() }; }
      }
      public Type ReturnedType
      {
          get { return typeof(string); }
      }
      public bool IsMutable
      {
          get { return false; }
      }
      #endregion
  }
}

NullableInt32Type.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using NHibernate.UserTypes;
using System.Data;
using NHibernate.Util;
using NHibernate;
using NHibernate.SqlTypes;

namespace Utilitario.GerenciaDados
{
  public class NullableInt32Type : IUserType
  {
      #region IUserType Members
      public bool Equals(object x, object y)
      {
          return object.Equals(x, y);
      }
      public int GetHashCode(object x)
      {
          return x.GetHashCode();
      }
      public object NullSafeGet(IDataReader rs, string[] names, object owner)
      {
          object valor = NHibernateUtil.Int32.NullSafeGet(rs, names[0]);
          Int32? inteiro = null;
          if (valor != null)
          {
              inteiro = (Int32)valor;
          }
          return inteiro;
      }
      public void NullSafeSet(IDbCommand cmd, object value, int index)
      {
          if (value == null)
          {
              NHibernateUtil.Int32.NullSafeSet(cmd, null, index);
          }
          else
          {
              Int32? inteiro = (int)value;
              NHibernateUtil.Int32.NullSafeSet(cmd, inteiro.Value, index);
          }
      }
      public object DeepCopy(object value)
      {
          return value;
      }
      public object Replace(object original, object target, object owner)
      {
          return original;
      }
      public object Assemble(object cached, object owner)
      {
          return cached;
      }
      public object Disassemble(object value)
      {
          return value;
      }
      public SqlType[] SqlTypes
      {
          get { return new SqlType[] { new StringSqlType() }; }
      }
      public Type ReturnedType
      {
          get { return typeof(string); }
      }
      public bool IsMutable
      {
          get { return false; }
      }
      #endregion
  }
}