Question

I have a object model like this

public class Parent{
 public int Id;
 public string Name;
 public Child Sibling 
}

public class Sibling {
 public int Id;
 public string Name;
 public Cousin Cousin
}

public class Cousin{
 public int Id;
 public string Name;
 public DateTime CreatedDate;
}

I’m trying to flatten or project? it to a model like this

public class ViewModelSibling {
   public int Id;
   public string Name;
}
public class ViewModel{
 public int ParentId;
 public string ParentName;
 public ViewModelSibling Sibling;
 public ViewModelSibling Cousin;
 public DateTime? CousinCreatedDate;
}

where Sibling and Cousin are Nullable

ControllerCode

 [HttpPost]
 public virtual ActionResult GetGridItems()
 {
     IQueryable<Parent> parents = GetParentsWhereCriteriaMet();
     var data = parents.Select( p => new ViewModel{
                       ParentId = p.Id,
                       ParentName = p.Name,
                       Sibling = new ViewModelSibling  { Id = p.Sibling.Id, Name = p.Sibling.Name},// if p.Sibling is null and exception is thrown
                       Cousin= new ViewModelSibling  {Id =p.Sibling.Cousin.Id, Name = p.Sibling.Cousin.Name}// if p.Sibling or p.Sibling.Cousin are null and exception is thrown
                       CousinCreatedDate = p.Sibling.Cousin.CreatedDate
                       } )
     return new JsonResult { Data = data };
 }

I’m trying to avoid using ToList() because I don’t want all of the Parent records to be returned. The ViewModel is going to be bound to a Telerik Grid using Ajax, this handles the paging.
I don’t want to use AutoMapper because I don’t want all fields and records to be returned.

How do I flatten this model without using ToList()?

Answer 1

Use either

Sibling = p.Sibling == null ? null : new ViewModelSibling(...)

or

Sibling = new ViewModelSibling{ Id = p.Sibling == null ? 0 : p.Sibling.Id, etc ... }

depending on your requirements.

etc…