Expand Wpf Treeview to support Sorting

Question

Hi I created this small example, and I would like to expand it to support Sorting.

public class Country
{
    public string Name { get; set; }
    public int Sor         


        

Answer 1

I don't think there is a default sort for TreeViews. You can either sort the items prior to entering them into the collection, or overwrite the ObservableCollection to include a Sort method.

I overwrite it in one of my projects:

public class SortableObservableCollection : ObservableCollection
{
    // Constructors
    public SortableObservableCollection() : base(){}
    public SortableObservableCollection(List l) : base(l){}
    public SortableObservableCollection(IEnumerable l) :base (l) {}

    #region Sorting

    /// 

    /// Sorts the items of the collection in ascending order according to a key.
    /// 
    /// The type of the key returned by .
    /// A function to extract a key from an item.
    public void Sort(Func keySelector)
    {
        InternalSort(Items.OrderBy(keySelector));
    }

    /// 

    /// Sorts the items of the collection in descending order according to a key.
    /// 
    /// The type of the key returned by .
    /// A function to extract a key from an item.
    public void SortDescending(Func keySelector)
    {
        InternalSort(Items.OrderByDescending(keySelector));
    }

    /// 

    /// Sorts the items of the collection in ascending order according to a key.
    /// 
    /// The type of the key returned by .
    /// A function to extract a key from an item.
    /// An  to compare keys.
    public void Sort(Func keySelector, IComparer comparer)
    {
        InternalSort(Items.OrderBy(keySelector, comparer));
    }

    /// 

    /// Moves the items of the collection so that their orders are the same as those of the items provided.
    /// 
    /// An  to provide item orders.
    private void InternalSort(IEnumerable sortedItems)
    {
        var sortedItemsList = sortedItems.ToList();

        foreach (var item in sortedItemsList)
        {
            Move(IndexOf(item), sortedItemsList.IndexOf(item));
        }
    }

    #endregion // Sorting
}

You would then sort it by calling something like

Countries.Sort(country => country.SortOrder);

I like overwriting it because it let me add additional functionality to it as well such as IndexOf or AddRange/RemoveRange