Filter list elements with hot chocolate (v13) GraphQL

Question

I'm using hot chocolate type extension and trying to filter list elements. here are my classes:

public class A
{
    public B b { get; set; }
}
public class B
{
    public string name {  get; set; }
    public List<C> c { get; set; }
}

public class C
{
    public bool isNew { get; set; }
}

query:

[UseFiltering]
public async Task<IQueryable<A>> GetA([Service] ISender sender)
{
    return await sender.Send(new GetAQuery());
}

I'm trying to filter the list elements by "isNew" (I want to be able to get only the elements with isNew = true ) the default list filters are "any, none, all, some", is there an option to add a 'where' filter to the schema definition?

I know I can extend the B object:

[ExtendObjectType(typeof(B))]
public class BResolver
{
    public List<C> NewC([Parent] B b)
        => b.c.Where(el=>el.isNew).ToList();
}

but that's not what I'm looking for, I don't want to add fields, I want to filter on the existing field

Answer 1

Looks like you need to use some keyword in where expression. You can filter high-level elements by child element fields like this:

query {
  a(where: { b: { c: { some: { isNew: { eq: true } } } } }) {
    b {
      name
      c {
        isNew
      }
    }
  }
}

If you need filter nested elements, you need to add [UseFiltering()] attribute:

public class A
{
    public B b { get; set; }
}
public class B
{
    public string name { get; set; }

    [UseFiltering()] // This row
    public List<C> c { get; set; }
}

public class C
{
    public bool isNew { get; set; }
}

and filter only nested objects like this:

query {
  a {
    b {
      name
      c(where: { isNew: { eq: true } }) {
        isNew
      }
    }
  }
}