Nhibernate ValueType Collection as delimited string in DB - nhibernate

Question

I have a legacy db that I am mapping with Nhibernate.
And in several locations a list och strigs or domain objects are mapped as a delimited string in the database. Either 'string|string|string' in the value type cases and like 'domainID|domainID|domainID' in the references type cases.
I know I can create a dummy property on the class and map to that fields but I would like to do it in a more clean way, like when mapping Enums as their string representation with the EnumStringType class.
Is a IUserType the way to go here?
Thanks in advance
/Johan

Answer 1

I am using this:
public class DelimitedList : IUserType
{
private const string delimiter = "|";
public new 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)
{
var r = rs[names[0]];
return r == DBNull.Value
? new List<string>()
: ((string)r).SplitAndTrim(new [] { delimiter });
}
public void NullSafeSet(IDbCommand cmd, object value, int index)
{
object paramVal = DBNull.Value;
if (value != null)
{
paramVal = ((IEnumerable<string>)value).Join(delimiter);
}
var parameter = (IDataParameter)cmd.Parameters[index];
parameter.Value = paramVal;
}
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(IList<string>); }
}
public bool IsMutable
{
get { return false; }
}
}
SplitAndTrim is my own extension of string. Then in the class (using ActiveRecord for mapping):
[Property(ColumnType = "My.Common.Repository.UserTypes.DelimitedList, My.Common.Repository")]
public virtual IList<string> FooBar { get; set; }