c# - How to do order by child class property for a list of parent class?

Question

Here parent class has child class in child class we have name how to make the list of parent as orderby using name property of child class. I used pq.OrderBy(z => z.Class1.Name != null).ToList(); but the list is not ordered as expected.

 class Program
        {
            static void Main(string[] args)
            {
                List<Parent> pq = new List<Parent>() {

                    new Parent () { Class1=new Child () { Name="d" } },
                    new Parent () { Class1=new Child () { Name="s" } },
                    new Parent () { Class1=new Child () { Name="y" } },
                    new Parent () { Class1=new Child () { Name="r" } },
                    new Parent () { Class1=new Child () { Name="b" } },
                    new Parent () { Class1=new Child () { Name="a" } }
                };

                var assa = pq.OrderBy(z => z.Class1.Name != null).ToList();
            }
        }

        public class Parent
        {
            public Child Class1 { get; set; }
        }

        public class Child
        {
            public string Name { get; set; }
        }

Answer 1

If you just want an ordered List you can use this:

var assa = pq.OrderBy(p => p.Class1.Name).ToList();

If it is possible that Class1 property is null use this:

var assa = pq.Where(p => p.Class1 != null).OrderBy(p => p.Class1.Name).ToList();

If you want to have those objects where Class1 is null at the end of the resulting List:

var assa = pq.Where(p => p.Class1 != null).OrderBy(p => p.Class1.Name).ToList();
assa.AddRange(pq.Where(p => p.Class1 == null));