Silverlight: disable automatic first-row selection after DataGrid binding

Question

I have a Silverlight DataGrid, a DataPager and a PagedCollectionView. After the PagedCollection view is bound to the DataGrid, the first row of the DataGrid is selected.

This behaviour does not happen, if i am using an ObservableCollection. But due to the DataPager, I need to use the PagedCollectionView.

I am using Silverlight 5 RC, and the SL 4 Toolkit.

Example of Usage:

View:

<sdk:DataGrid x:Name="gridSomeItems" ItemsSource="{Binding SomeItems, Mode=TwoWay}" SelectedItem="{Binding SelectedItem, Mode=TwoWay}" CanUserSortColumns="True">
    <sdk:DataGrid.Columns>
        <sdk:DataGridTextColumn Header="Column1" Width="*" Binding="{Binding Column1}" />
    </sdk:DataGrid.Columns>
</sdk:DataGrid>
<sdk:DataPager Source="{Binding Path=ItemsSource, ElementName=gridSomeItems}"/>

ViewModel:

public class SomeViewModel : ViewModelBase
{
    public SomeViewModel(IDataAccess dataAccess)
    {
        _dataAccess = dataAccess;
        _dataAccess.GetSomeItemsCompleted += GetSomeItemsCompleted;
        _dataAccess.GetSomeItems();           
    }

    public PagedCollectionView SomeItems { get; set; }
    public SomeItem SelectedItem { get; set; }

    private void GetSomeItemsCompleted(GetSomeItemsCompletedEventArgs e)
    {
        SomeItems = new PagedCollectionView(e.Result.SomeItems);         
        RaisePropertyChanged("SomeItems");
    }
}

score 3 · Accepted Answer · answered Oct 03 '11 at 11:59

The best workaround is to set a _isLoading flag. The following code would be the correct code for the ViewModel:

public class SomeViewModel : ViewModelBase
{
    private bool _isLoading;

    public SomeViewModel(IDataAccess dataAccess)
    {
        _dataAccess = dataAccess;
        _dataAccess.GetSomeItemsCompleted += GetSomeItemsCompleted;
        _isLoading = true;
        _dataAccess.GetSomeItems();           
    }

    public PagedCollectionView SomeItems { get; set; }
    public SomeItem SelectedItem { get; set; }

    private void GetSomeItemsCompleted(GetSomeItemsCompletedEventArgs e)
    {
        SomeItems = new PagedCollectionView(e.Result.SomeItems);         
        SomeItems.CurrentChanged += CurrentItemChanged;
        RaisePropertyChanged("SomeItems");
        SomeItems.MoveCurrentTo(null);
        _isLoading = false;     
    }

    private void CurrentItemChanged(object sender, System.EventArgs e)
    {
        if (!_isLoading)
        {
            SelectedItem = SomeItems.CurrentItem as SomeItem;
            // Do something more...
        }
    }   
}

Please have a look at the row SomeItems.MoveCurrentTo(null); - This command really sets the CurrentItem of the PagedCollectionView to null (not selected).

It is still a workaround... Would be great if anybody came up with a better solution.

Bryant · Answer 2 · 2011-09-29T16:03:47.993

2

Not sure why that is happening unless you are somehow setting the SelectedItem property in your code somehow.

A simple solution to the problem would be to use a Behavior on the DataGrid that sets the SelectedIndex to -1 when the loaded event fires.

edited Sep 29 '11 at 16:03

answered Sep 29 '11 at 15:31

Bryant

8,660
1
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53

Hm. That could be a workaround - but the SelectedItem does also change, when the DataPager moves to the next page. So i would have to catch this event too... – Gerwald Sep 29 '11 at 16:57

score 0 · Answer 3 · answered Oct 17 '15 at 19:43

I solved the situation by putting the MoveCurrentTo(null) inside the PageIndexChanged event. Like that:

XAML

<data:DataPager x:name="pager" PageIndexChanged="dataPagerGroup_PageIndexChanged" />

C#

private void PageIndexChanged(object sender, EventArgs e)
{
    (this.pager.Source as PagedCollectionView).MoveCurrentTo(null);
}

score 0 · Answer 4 · answered Sep 29 '11 at 15:32

0

The first thing that comes to mind is that you need to do something like:

private PagedCollectionView someItems;
public PagedCollectionView SomeItems
{
    get { return someItems; }

    set
    {
        if (someItems != value)
        {
            someItems = value;
            RaisePropertyChanged("SomeItems");
        }
    }
}

And implement that same strategy for SelectedItem.

answered Sep 29 '11 at 15:32

Anatolii Gabuza

6,184
2
36
54

Thats right, but I am fireing the RaisePropertyChanged in the Load-Completed event (if you have a Look on the method `GetSomeItemsCompleted`). The `SelectedItem` doesn't need to be raised, because this should only be set by the grid and not from the ViewModel. – Gerwald Sep 29 '11 at 16:52

Silverlight: disable automatic first-row selection after DataGrid binding

View:

ViewModel:

4 Answers4