Class with many inheriting class with one generic list

Question

I have a class

public class BaseHeaderFooterItem
{
  public string Title { get; set; }
  public string EnTitle { get; set; }
  public HyperLink Link { get; set; }
  public int Level { get; set; }
  public HyperLink MobileLink { get; set; }
}

Many other class inherit from him I want to have on generic list in the class BaseHeaderFooterItem that will be able to hold a list from any type of the inherited classes. something like this:

public class BaseHeaderFooterItem
    {
      public string Title { get; set; }
      public string EnTitle { get; set; }
      public HyperLink Link { get; set; }
      public int Level { get; set; }
      public HyperLink MobileLink { get; set; }
      public List<T> Descendants { get; set; }
    }

How can I do it ?

Answer 1

You could try to keep a properties to hold a child collection of the base type.

public class BaseHeaderFooterItem
{
  public string Title { get; set; }
  public string EnTitle { get; set; }
  public HyperLink Link { get; set; }
  public int Level { get; set; }
  public HyperLink MobileLink { get; set; }

  // here you can add instances of BaseHeaderFooterItem and any inherits type
  public List<BaseHeaderFooterItem> Descendants { get; set; } 
}

And you could add any tpe that inherits from BaseHeaderFooterItem , for sample:

var list = new List<BaseHeaderFooterItem>();

list.Add(new BaseHeaderFooterItem() {
        Title = "Test"
        Descendants = new List<BaseHeaderFooterItem>()
                                 {
                                    new ChildHeaderFooterItem() { /* properties */}
                                 }
    });

Or if you need a specif type for each BaseHeaderFooterItem , than try to specif the generic on the declaration.

public class BaseHeaderFooterItem<T>
             where T : BaseHeaderFooterItem<T>
{
  public string Title { get; set; }
  public string EnTitle { get; set; }
  public HyperLink Link { get; set; }
  public int Level { get; set; }
  public HyperLink MobileLink { get; set; }

  // only T types
  public List<T> Descendants { get; set; }
}

var list = new List<BaseHeaderFooterItem<ChildType>>();

list.Add(new BaseHeaderFooterItem() {
        Title = "Test"
        Descendants = new List<ChildType>()
                                 {
                                    new ChildHeaderFooterItem() { /* properties */}
                                 }
    });

Answer 2

You may use this pattern

public interface IBaseHeaderFooterItem
{
    string Title { get; set; }
    string EnTitle { get; set; }
    public HyperLink Link { get; set; }
    int Level { get; set; }
    HyperLink MobileLink { get; set; }
}

public abstract class BaseHeaderFooterItem<T> : IBaseHeaderFooterItem 
                                                where T : IBaseHeaderFooterItem
{
    public List<T> Descendants { get; set; }

     public abstract string Title { get; set; }
     public abstract string EnTitle { get; set; }
     public abstract HyperLink Link { get; set; }
     public abstract int Level { get; set; }
     public abstract HyperLink MobileLink { get; set; }
}

Then you can inherit from BaseHeaderFooterItem<T> and T is constraint to be a class implementing IBaseHeaderFooterItem and having all those properties.