WPF databinding to a linked list - wpf

Question

I want to databind a ListBox to a linked list
public class MyClass
{
public string MyText{ get; set; }
public MyClass PreviousItem{ get; set; }
}
I want to use an instance of MyClass as the datasource of a ListBox, to basically show a list of the MyClass instance and all it's PreviousItems.
Of course binding to an instance of MyClass will result in only the topmost parent being shown. What would be the best approach for this?

Answer 1

Why do you need a custom implementation of a LinkedList in the first place? There is a .NET implementation already: System.Collections.Generic.LinkedList
Other than that, you have basically three options:
Recommended: If it fits your
business logic, impement at least
IEnumerable in MyClass (like the .NET lists)
Create a ViewModel which traverses
your items of MyClass and
puts them into an
ObservableCollection
Create an IValueConverter object to
convert your linked list to a
collectionType like
ObservableCollection

Answer 2

You can use BCL LinkedList<T> class. Or alternatively if you like your class very much you can implement IEnumerable like this
public class MyClass : IEnumerable<MyClass>
{
public string MyText { get; set; }
public MyClass PreviousItem { get; set; }
public IEnumerator<MyClass> GetEnumerator()
{
var item = this;
do
{
yield return item;
item = item.PreviousItem;
} while (item != null);
}
IEnumerator IEnumerable.GetEnumerator()
{
return GetEnumerator();
}
}

Answer 3

Actually implementing IEnumerable would suffice:
public IEnumerable<MyClass> TraverseItemsFromCurrent
{
get
{
var current = this;
yield return current;
while (current.PreviousItem != null)
{
current = current.PreviousItem;
yield return current;
}
}
}
And yes, using LinkedList<T> might be easier and more adequate to your purpose.

Answer 4

The easiest thing (in my opinion) is to implement IEnumerable
public class MyClass : IEnumerable<MyClass>
{
public string MyText { get; set; }
public MyClass PreviousItem { get; set; }
IEnumerator<MyClass> IEnumerable<MyClass>.GetEnumerator()
{
for (var item = this; item.PreviousItem != null; item = item.PreviousItem)
yield return item;
}
public IEnumerator GetEnumerator()
{
return ((IEnumerable<MyClass>)this).GetEnumerator();
}
}
Then you code would look like this
public Window1()
{
MyClass item1 = new MyClass() {MyText = "No1"};
MyClass item2 = new MyClass() {MyText = "No2"};
MyClass item3 = new MyClass() {MyText = "No3"};
MyClass item4 = new MyClass() {MyText = "No4"};
item4.PreviousItem = item3;
item3.PreviousItem = item2;
item2.PreviousItem = item1;
DataContext = item4; // your first item
}