Sort ObservableCollection through C#

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Introduction

Basically, if there is a need to display a sorted collection, please consider using the CollectionViewSource class: assign (“bind”) its Source property to the source collection — an instance of the ObservableCollection<T> class.

The idea is that CollectionViewSource class provides an instance of the CollectionView class. This is kind of “projection” of the original (source) collection, but with applied sorting, filtering, etc.

References:

  • How to: Sort and Group Data Using a View in XAML.
  • WPF’s CollectionViewSource.

Live Shaping

WPF 4.5 introduces “Live Shaping” feature for CollectionViewSource.

References:

  • WPF 4.5 New Feature: Live Shaping.
  • CollectionViewSource.IsLiveSorting Property.
  • Repositioning data as the data’s values change (Live shaping).

Solution

If there still a need to sort an instance of the ObservableCollection<T> class, here is how it can be done.
The ObservableCollection<T> class itself does not have sort method. But, the collection could be re-created to have items sorted:

// Animals property setter must raise "property changed" event to notify binding clients.
// See INotifyPropertyChanged interface for details.
Animals = new ObservableCollection<string>
    {
        "Cat", "Dog", "Bear", "Lion", "Mouse",
        "Horse", "Rat", "Elephant", "Kangaroo",
        "Lizard", "Snake", "Frog", "Fish",
        "Butterfly", "Human", "Cow", "Bumble Bee"
    };
...
Animals = new ObservableCollection<string>(Animals.OrderBy(i => i));

Additional details

Please note that OrderBy() and OrderByDescending() methods (as other LINQ–extension methods) do not modify the source collection! They instead create a new sequence (i.e. a new instance of the class that implements IEnumerable<T> interface). Thus, it is necessary to re-create the collection.

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