EFCore 2.0 - Include & ThenInclude : child collection -- grandchild collection [duplicate]

Question

For a model like below

public class Parent
{
    public int Id { get; set; }

    public List<Child> Children { get; set; }
}

public class Child
{
    public int ChildId { get; set; }

    public int ParentId { get; set; }

    public List<Child> GrandChildren { get; set; }
}

public class GrandChild
{
    public int GrandChildId { get; set; }

    public int ChildId { get; set; }
}

How do I write a query that gets all the Children and GrandChildren in the Include/ThenInclude statements?

var record = GetAll()
 .Where(r => r.Id == 4)
 .Include(r => r.Children)
     .ThenInclude(????????????)

In the "ThenInclude" statement, I cannot use a select statement to get the grandchildren. What will be the right way to get the GrandChildren collection?

Much appreciated.

Answer 1

Just type the navigation property name:

.ThenInclude(c => c.GrandChildren)

It's a current Intellisense issue specifically mentioned in the Including multiple levels section of the EF Core documentation:

Note

Current versions of Visual Studio offer incorrect code completion options and can cause correct expressions to be flagged with syntax errors when using the ThenInclude method after a collection navigation property. This is a symptom of an IntelliSense bug tracked at https://github.com/dotnet/roslyn/issues/8237. It is safe to ignore these spurious syntax errors as long as the code is correct and can be compiled successfully.