BindingList<> (master) with a composed BindingList<> (child) reference

I have a situation where a BindingList<> represents a collection of POCOs that have sub-collections of similar nature, Here is a sample code of two such POCOs and their respective lists:

The DirectoryTypePoco

  public class DirectoryTypePoco : IBasePoco
  {

    public DirectoryTypePoco()
    {

    }

    public DirectoryTypePoco(Int16 directoryTypeId, String directoryImplementation, String directoryDescription, DirectoryDefinitionPocoList directoryDefinition)
    {
      DirectoryTypeId = directoryTypeId;
      DirectoryImplementation = directoryImplementation;
      DirectoryDescription = directoryDescription;
      DirectoryDefinition = directoryDefinition;
    }

    public Int16 DirectoryTypeId { get; set; }
    public String DirectoryImplementation { get; set; }
    public String DirectoryDescription { get; set; }
    public DirectoryDefinitionPocoList DirectoryDefinition { get; set; }

    public object GenerateEntity(GenericRepository repository, params object[] parameters)
    {
      var lastMaxEntityId = repository.GetQuery<DirectoryType>().Select(select => @select.DirectoryTypeId).DefaultIfEmpty().Max();

      var newEntity = new DirectoryType
      {
        DirectoryTypeId = (short)(lastMaxEntityId + 1),
        DirectoryImplementation = this.DirectoryImplementation,
        DirectoryDescription = this.DirectoryDescription
      };

      return newEntity;
    }

  }

And the BindingList<DirectoryTypePoco>:

  public class DirectoryTypePocoList : BindingList<DirectoryTypePoco>
  {

    public DirectoryTypePocoList()
    {
      using (var repository = new GenericRepository(new PWRDbContext()))
      {
        var query = repository.GetQuery<DirectoryType>();

        foreach (var r in query)
        {
          Add(new DirectoryTypePoco(r.DirectoryTypeId, r.DirectoryImplementation, r.DirectoryDescription, new DirectoryDefinitionPocoList(r.DirectoryTypeId)));
        }
      }
    }

    public DirectoryTypePocoList(short directoryTypeId)
    {
      using (var repository = new GenericRepository(new PWRDbContext()))
      {
        var query = repository.GetQuery<DirectoryType>(where => where.DirectoryTypeId == directoryTypeId);

        foreach (var r in query)
        {
          Add(new DirectoryTypePoco(r.DirectoryTypeId, r.DirectoryImplementation, r.DirectoryDescription, new DirectoryDefinitionPocoList(r.DirectoryTypeId)));
        }
      }
    }
  }

The second object: DirectoryDefinitionPoco

  public class DirectoryDefinitionPoco : IBasePoco
  {

    public DirectoryDefinitionPoco()
    {

    }

    public DirectoryDefinitionPoco(Int16 directoryTypeId, Byte parameterId, String parameterName, String parameterValidation, Boolean encryptionRequired, PocoChangeType changeType = PocoChangeType.None)
    {
      DirectoryTypeId = directoryTypeId;
      ParameterId = parameterId;
      ParameterName = parameterName;
      ParameterDescription = parameterName;
      ParameterRequired = false;
      ParameterValidation = parameterValidation;
      EncryptionRequired = encryptionRequired;
    }

    public Int16 DirectoryTypeId { get; set; }
    public Byte ParameterId { get; set; }
    public String ParameterName { get; set; }
    public String ParameterDescription { get; set; }
    public String ParameterValidation { get; set; }
    public Boolean ParameterRequired { get; set; }
    public Boolean EncryptionRequired { get; set; }    

    public object GenerateEntity(GenericRepository repository, params object[] parameters)
    {
      var masterId = (short) parameters[0];
      var lastMaxEntityId = repository.GetQuery<DirectoryDefinition>(where => where.DirectoryTypeId == masterId).Select(select => @select.ParameterId).DefaultIfEmpty().Max();

      var newEntity = new DirectoryDefinition
      {
        DirectoryTypeId = (short)parameters[0],
        ParameterId = (byte)(lastMaxEntityId + 1),
        ParameterName = this.ParameterName,
        ParameterDescription = this.ParameterDescription,
        ParameterValidation = this.ParameterValidation,
        ParameterRequired = this.ParameterRequired,
        EncryptionRequired = this.EncryptionRequired
      };

      return newEntity;
    }
  }

And BindingList<DirectoryDefinitionPoco>:

  public class DirectoryDefinitionPocoList : BindingList<DirectoryDefinitionPoco>
  {
    public DirectoryDefinitionPocoList(short directoryTypeId)
    {
      using (var repository = new GenericRepository(new PWRDbContext()))
      {
        var query = repository.GetQuery<DirectoryDefinition>(where => where.DirectoryTypeId == directoryTypeId);

        foreach (var r in query)
        {
          Add(new DirectoryDefinitionPoco(r.DirectoryTypeId, r.ParameterId, r.ParameterName, r.ParameterValidation, r.EncryptionRequired));
        }
      }
    }

    public List<DirectoryDefinition> GetSourceQuery()
    {
      List<DirectoryDefinition> result;

      using (var repository = new GenericRepository(new PWRDbContext()))
      {
        result =  repository.GetQuery<DirectoryDefinition>().ToList();
      }

      return result;
    }

    public List<DirectoryDefinition> GetSourceQuery(short directoryTypeId)
    {
      List<DirectoryDefinition> result;

      using (var repository = new GenericRepository(new PWRDbContext()))
      {
        result = repository.GetQuery<DirectoryDefinition>(where => where.DirectoryTypeId == directoryTypeId).ToList();
      }

      return result;
    }
  }

On the form, I load the data into the grid through a BindingSource component. The child rows are added properly and the data is valid.

Sample application

Here is the issue: I'm able to add new DirectoryTypePoco but when try to add a DirectoryDefinitionPoco, in the code, the the DirectoryDefinitionPocoobject that I get has a zero for it's parent object. In the above picture, the Test5.dll234 is a DirectoryTypePoco with DirectoryTypeId = 8 and all child under it are ok except the new one I create. What am I suppose to do to make sure I have Master-Child relation in this case?

Solution

Ok. It seems that there are two thing I should have noticed in my design.

The individual child Poco needs to know the parent Poco through a reference.
The DevExpress Grid has methods that allow for retrieving the attached data to a parent row while in the child view' particular row.

The first part is straightforwards: add a new property in the child poco of parent poco type.

This however, in my case, doesn't solve my issue as when I visually add a new row on the grid, the default constructor is invoked and it takes no parameters and hence the parent poco reference will remain NULL and the Ids (numeric) will be defaulted to 0

The second point helped fix my issue completely. I was able to conjure up an extension method for the XtraGrid's GridView as follows:

public static class DevExpressGridHelper
{
  public static IBasePoco GetPocoFromSelectedRow(this BaseView view)
  {
    return (IBasePoco)view.GetRow(((GridView)view).FocusedRowHandle);
  }

  public static IBasePoco GetParentPocoFromSelectedRow(this GridView view)
  {
    if (view.ParentView !=null)
    {
      // return (IBasePoco)(view.ParentView).GetRow(((GridView)(view.ParentView)).FocusedRowHandle);  
      return (IBasePoco)((GridView)view.ParentView).GetFocusedRow();
    }

    return null;

  }

}

And used it as follows:

private void GridMain_Level_1_RowUpdated(object sender, RowObjectEventArgs e)
{
  var view = sender as GridView;

  if (view == null)
  {
    return;
  }

  var pocoObject = e.Row as DirectoryDefinitionPoco;

  if (pocoObject == null)
  {
    return;
  }

  var parentPocoObject = view.GetParentPocoFromSelectedRow();

  if (parentPocoObject == null)
  {
    return;
  }

  if (view.IsNewItemRow(e.RowHandle))
  {
    Create(pocoObject, parentPocoObject);
  }
  else
  {
    Update(pocoObject);
  }
}