CODEWITHSUNDEEP
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Gurpreet Singh
Gurpreet Singh

Reputation: 1731

Sort ObservableCollection - what is the best approach?

I have a ObservableCollection , where MyData is a class with 4 properties i.e. int id, string name, bool IsSelected, string IsVisible.

This ObservableCollection is binded to a combobox with checkboxes(Cities data for example). Now, when the user checks the checkboxes then next time when he opens the drop down - all selections should come on top in ascending order by name.

I have also implemented auto complete when the user types in 3 chars in the combobox, the drop down will open showing all the selections first, then then all the items starting from the 3 chars type in by the user.

I have researched and implemented the following code and it is working fine, but i want to know whether this is the best approach or can i implement this in a better manner, code is :

        IEnumerable<MyData> sort;
        ObservableCollection<MyData> tempSortedCities = new ObservableCollection<MyData>();
        sort = City.OrderByDescending(item => item.IsSelected).ThenBy(item => item.Name.ToUpper()) ; 
       // City is my observablecollection<MyData> property in my Model binded to combobox in UI
        foreach (var item in sort)
            tempSortedCities.Add(item);


        City.Clear(); // City is my observablecollection<MyData> property in my Model
        City = tempSortedCities;
        tempSortedCities = null;
        sort = null;

Thanks in advance for your time !

Upvotes: 15

Views: 13483

Answers (1)

Pavlo Glazkov
Pavlo Glazkov

Reputation: 20746

ICollectionView seems to be a perfect fit for this. It was designed specifically for sorting, filtering and grouping of a collection without modifying the original collection.

You can get an instance of ICollectionView for your collection using the following code:

var sortedCities  = CollectionViewSource.GetDefaultView(City);

Then you can setup sorting by adding instances of SortDescription type to the ICollectionView.SortDescriptions collection:

sortedCities.SortDescriptions.Add(new SortDescription("IsSelected", ListSortDirection.Descending));
sortedCities.SortDescriptions.Add(new SortDescription("Name", ListSortDirection.Ascending));

Then you can bind your ComboBox directly to the collection view (instead of City collection) and it will display already sorted data.

Upvotes: 23

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