C# Parent Child - Save To File ( I want to Save Parent Child Hyerarchy to the file)

Question

i want to save Parent Child Hierarchy To the File p.s Console Print Can Do , but i try with streamwriter to write to the text ,but cant and wants that ID should be unique for the new person in the list any advice?

        Person person1 = new Person() { ID = 1, Name = "X..Parent" };
          Person person2 = new Person() { ID = 2, Name = "Y...ChildOF..X" };
            Person person3 = new Person() { ID = 3, Name = "Child of..Y" }; 
            Person person4 = new Person() { ID = 4, Name = "Child of..Y" }; 

        person1.Children.Add(person2);
        person2.Children.Add(person3);
        person2.Children.Add(person4);
        PersonList people1 = new PersonList();
        people1.Add(person1):
        people1.Save(@"C:\People.txt");
        Print(people1);
    }
   public static void Print(IEnumerable<Person> people, int level = 0)
    {
        foreach (var item in people)
        {
            Console.WriteLine($"{new string(' ', level * 2)}{item}");

            Print(item.Children, level + 1);
        }

    }
}

class PersonList : List<Person>
{
    new public void Add(Person item)
    {

        base.Add(item);
    }

    public  void Save(string path)
    {
       
    }

}
class Person
{
    public Person()
    {
        Children = new List<Person>();
    }
    public int ID { get; set; }
    public string Name { get; set; }
    public ICollection<Person> Children { get; set; }
    public override string ToString()
    {
        return $"ID: {ID}, Name: {Name}";
    }

}

Answer 1

Here you go

public class PersonList {
    List<Person> _people = new();
    public List<Person> People {get {return _people;} }
    public void Add(Person item) {

        _people.Add(item);
    }

    public void Save(string path) {
        using (var f = System.IO.File.Open(path, FileMode.Create))
        using (var s = new StreamWriter(f)) {
            int depth = 0;
            foreach (Person item in _people) {
                s.WriteLine(item.ToString());
                Traverse(depth+1, s, item);
            }
        }
    }

    public void Traverse(int depth, StreamWriter s , Person p) {

        foreach (var child in p.Children) {
            s.Write(new string(' ', depth * 2));
            s.WriteLine(child.ToString());
            Traverse(depth+1, s, child);
        }

    }

}

plus

     people1.Save(@"People.txt");
     Print(people1.People);