ICollectionView Sorting issue in ListView

Question

I saw ICollectionView being introduced with WPF to handle situations when you need sorting and filtering enabled. I even saw few articles which sort items, but my main concern is why my approach is failing. Lets see my code :

 <ListView ItemsSource="{Binding}" x:Name="lvItems" GridViewColumnHeader.Click="ListView_Click">
            <ListView.View>
                <GridView AllowsColumnReorder="True">
                    <GridViewColumn Header="Id" DisplayMemberBinding="{Binding Id}" />
                    <GridViewColumn Header="Name" DisplayMemberBinding="{Binding Name}" />
                    <GridViewColumn Header="Developer">
                        <GridViewColumn.CellTemplate>
                            <DataTemplate>
                                <TextBlock Text="{Binding Path=Developer}" />
                            </DataTemplate>
                        </GridViewColumn.CellTemplate>
                    </GridViewColumn>
                    <GridViewColumn Header="Salary">
                        <GridViewColumn.CellTemplate>
                            <DataTemplate>
                                <TextBlock Text="{Binding Path=Salary}" />
                            </DataTemplate>
                        </GridViewColumn.CellTemplate>
                    </GridViewColumn>

                </GridView>
            </ListView.View>
        </ListView>

In codebehind, when the Item is clicked I am doing like this :

  ICollectionView Source { get; set; }


        private void ListView_Click(object sender, RoutedEventArgs e)
        {
            GridViewColumnHeader currentHeader = e.OriginalSource as GridViewColumnHeader;
            if(currentHeader != null && currentHeader.Role != GridViewColumnHeaderRole.Padding)
            {
                //using (this.Source.DeferRefresh())
                //{
                    SortDescription currentPropertySort = this.Source.SortDescriptions.FirstOrDefault<SortDescription>(item => item.PropertyName.Equals(currentHeader.Column.Header.ToString()));
                    if (currentPropertySort != null)
                    {
                        if (currentPropertySort.Direction == ListSortDirection.Ascending)
                            currentPropertySort.Direction = ListSortDirection.Descending;
                        else
                            currentPropertySort.Direction = ListSortDirection.Ascending;

                    }
                    else
                        this.Source.SortDescriptions.Add(new SortDescription(currentHeader.Column.Header.ToString(), ListSortDirection.Ascending));


                //}
                    this.Source.Refresh();
                    this.lvItems.DataContext = this.Source;
                    this.lvItems.UpdateLayout();
            }


        }

So whenever the header for the ListBox is clicked, the item need to be sorted. I am holding the collection using a property called Source and then using it by calling lvItems.DataContext = this.Source. But the code does not seem to be working.

To all the viewers of this post, I have implemented this already. If you want to see take a look : abhisheksur.com/2010/08/… Thanks — abhishek
– abhishek, Commented Aug 29, 2010 at 23:55

ASanch · Accepted Answer · 2010-08-23 20:53:37Z

3

Here's an updated version of your ListView_Click method that somewhat works. I'm not sure exactly what sorting behavior you were looking for but the version below "stacks up" a set of sort descriptions, making the last clicked column as the "primary sort description". I hope this makes sense and I hope the code below helps. =)

private void ListView_Click(object sender, RoutedEventArgs e)
{
    GridViewColumnHeader currentHeader = e.OriginalSource as GridViewColumnHeader;
    if(currentHeader != null && currentHeader.Role != GridViewColumnHeaderRole.Padding)
    {
        if (this.Source.SortDescriptions
            .Count((item) => item.PropertyName.Equals(currentHeader.Column.Header.ToString())) > 0)                
        {
            SortDescription currentPropertySort = this.Source
                .SortDescriptions
                .First<SortDescription>(item => item.PropertyName.Equals(currentHeader.Column.Header.ToString()));

            //Toggle sort direction.
            ListSortDirection direction = 
                (currentPropertySort.Direction == ListSortDirection.Ascending)?
                ListSortDirection.Descending : ListSortDirection.Ascending;

            //Remove existing sort
            this.Source.SortDescriptions.Remove(currentPropertySort);
            this.Source.SortDescriptions.Insert(0, new SortDescription(currentHeader.Column.Header.ToString(), direction));
        }
        else
        {
            this.Source.SortDescriptions.Insert(0, new SortDescription(currentHeader.Column.Header.ToString(), ListSortDirection.Ascending));
        }

        this.Source.Refresh();
    }
}

EDIT:

By the way, one of the problems in your code above is your call to "FirstOrDefault" to query an existing SortDescription. See, SortDescription is a struct, which is non-nullable so the call to FirstOrDefault will never be null and will always return an instance. Therefore, the "else-statement" in your code above will never get called.

edited Aug 23, 2010 at 20:53

answered Aug 23, 2010 at 20:48

ASanch

10.4k49 silver badges33 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

abhishek Over a year ago

Wow thats great. I just overlooked the type of SortDescription and hence more credits to you for pointing me with that. Thank you so much for your code.

ARZ Over a year ago

In my case the ListView only has been sorted at the first time, and Refresh() does not work at all! so what is the problem?

Collectives™ on Stack Overflow

ICollectionView Sorting issue in ListView

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest