Fluent Nhibernate List<string> mapping

Question

I have a simple class with a IList<string> property. How to map this property in Fluent Nhibernate ?

[Serializable]
public class ExportTask
{
    private IList<string> _csvExportList = new List<string>();

    public ExportTask()
    {}

    public virtual IList<string> CsvExportList
    {
        get { return _csvExportList; }
        set { _csvExportList = value; }
    }
}

public class ExportTaskMap : SubclassMap<ExportTask>
{
    public ExportTaskMap()
    {           
        HasMany(x => x.CsvExportList)
               .Element("CsvExportList")
               .Cascade
               .AllDeleteOrphan();
    }
}

Following error occurs:

Initializing -failed to lazily initialize a collection of role: MyApp.Tasks.ExportTask.CsvExportList, no session or session was closed

When calling addrange on the collection:

var exportList = new List<string>()
                     {
                        {"item1"},
                        {"item2"}
                      };

CsvExportList.AddRange(exportList);

Answer 1

It truns out we can use AsList mapping with a column for the list index and allworks great. I wonder why there are no answers out there for this simple usecase. Hope it helps out someone.

public class ExportTaskMap : SubclassMap<ExportTask>
{
  public ExportTaskMap()
  {           
     HasMany(x => x.CsvExportList)
           .Element(@"CsvProperty")
           .KeyColumn(@"ExportTask_id")
           .Table(@"CsvExportProperties")
           .AsList(x => x.Column(@"CsvPropertyListIndex"))
           .Not.LazyLoad();
  }
}

And the mapped table will look like the following in the database.

Answer 2

Would be helpful to see the error you get, but one thing seems to be obvious: you are missing setter of the IList<string> CsvExportList . So, mapping should target the field

HasMany<string>(Reveal.Property<string>("_csvExportList"))

Check these how to handle field mapping:

• Private collection mapping in fluent nhibernate
• How do I map a protected collection in Fluent NHibernate?

Or change your IList<string> to have at least protected setter (I personally would go this way) and remove the readonly setting.

private IList<string> _csvExportList;
public virtual IList<string> CsvExportList
{
    get { return _csvExportList ?? (_csvExportList = new List<string>(); }
    protected set { _csvExportList = value; }
}

These are hints, the exception or error you get could tell us more