Problem with Custom Association Resolver

Hi, I'm having a problem setting up a Custom Association Resolver for an existing database. I've based my Custom Association Resolver on examples from this forum. My database tables have primary key constraints set up but no foreign keys. My parent entity (design) has a composite key. The child entity (item) has a composite key, which includes the composite key from the parent (design) entity. I'm trying to set up this parent/child relationship in LightSpeed. I'm receiving the following error message:

"Unable to materialize field [Dwg] on type [ConsoleApplication2.Item]. Check your table has an Id column and that your mappings are correct. See inner exception for details. "

I'm not sure what I'm missing. My files are attached, thanks.

The problem is that the Dwg column is mapped twice in Item -- once via Item.Id.Dwg and once via Item.DesignId.Dwg. Basically because you have an association from Item to Design, the LightSpeed designer generates a foreign key field (of composite type, to match the composite key of the Design entity) in the Item entity; but in this case all the columns of the foreign key are already part of the Item.Id primary key.

What you will need to do is set the association's Generation property to None and manually implement the association in the partial classes, but NOT implement the Item._designId field. Here's what it will look like:

partial class Design
{
  // Implementing the to-many end of the association by hand

  [AssociationResolver(typeof(...))]
  private readonly EntityCollection<Item> _items = new EntityCollection<Item>();

  public EntityCollection<Item> Items
  {
    get { return Get(_items); }
  }
}

partial class Item
{
  // Implementing the to-one end of the association by hand

  // Note no _designId foreign key field

  [AssociationResolver(typeof(...))]
  private readonly EntityHolder<Design> _design = new EntityHolder<Design>();

  public Design Design
  {
    get { return Get(_design); }
    set { Set(_design, value); }
  }
}

With these changes your test case works for me -- let us know if you run into any problems or need any further guidance.

Thank you Ivan, your solution worked great.