When using INotifyDataErrorInfo, items are still validated even when the ValidationType property is None.

Please note that when the AutoGeneratedColumns property is set to true, the item's HasErrors property will be evaluated, but only once.

The MatchAllTerms search mode doesn't behave as epxected when the GroupRenderMode property of RadGridView is set to Flat.

To work this around, set the GroupRenderMode property of RadGridView to True.

Hi guys,

we have a messaging service that broadcasts a couple of messages every 1-5 seconds.

When our client module receives those messages, we want to append them at the bottom of a grid (RadGridView).

After appending them, we also want to scroll to the very bottom of that grid, so that the newest and therefore bottommost items come into view.

Documentation and forums suggest we go the AttachedBahaviour and ScrollIntoViewAsync way.

Our behaviour looks like this:

    public class ScrollToNewItemBehavior : Behavior<RadGridView>
    { 
        public static bool GetIsEnabled(DependencyObject obj) => (bool)obj.GetValue(IsEnabledProperty);
        public static void SetIsEnabled(DependencyObject obj, bool value) => obj.SetValue(IsEnabledProperty, value);
        public static readonly DependencyProperty IsEnabledProperty = DependencyProperty.RegisterAttached("IsEnabled", typeof(bool), typeof(ScrollToNewItemBehavior), new PropertyMetadata(false, OnIsEnabledChanged));
        private static void OnIsEnabledChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            if (d is RadGridView gridView)
                gridView.Items.CollectionChanged += (s, args) =>
                {
                    if (args.Action == NotifyCollectionChangedAction.Add)
                    {
                        gridView.ScrollIntoViewAsync(args.NewItems[0], gridView.Columns[0], null);

                        // exchanging args.NewItems[0] for gridView.Items[gridView.Items.Count-1] yields same result
                        //gridView.ScrollIntoViewAsync(gridView.Items[gridView.Items.Count-1], gridView.Columns[0], null);
                    }
                };
        } 
    }

Our Message class:

    public class Message : ModelBase<Message>
    {
        public string Text { get; set; }
    }

Our Messages collection in the ViewModel:

        private RadObservableCollection<Message> _messages;
        public RadObservableCollection<Message> Messages
        {
            get => _messages;
            set
            {
                _messages = value;
                NotifyPropertyChanged(m => m.Messages);
            }
        }

The collection is updated (in the ViewModel) like this:

            Task.Run(async () =>
            {
                for (int i = 0; ; i++)
                {
                    await Task.Delay(1000);
                    Messages.Add(new Message { Text = $"{i} - sftrvwj,erhvtwejhrfvtjlwehftrwejh" });
                }
            });

The grid is defined like this:

    <telerik:RadGridView
        x:Name="gridView"
        ItemsSource="{Binding Messages, Mode=OneWay}"
        IsSynchronizedWithCurrentItem="False"
        IsPropertyChangedAggregationEnabled="True"
        AutoGenerateColumns="False" 
        SelectionMode="Single"
        CanUserFreezeColumns="False"
        EnableColumnVirtualization="True"
        EnableRowVirtualization="True"
        CanUserDeleteRows="False"
        CanUserInsertRows="False"
        behaviours:ScrollToNewItemBehavior.IsEnabled="True"
        CanUserGroupColumns="False"
        IsReadOnly="True"
        IsManipulationEnabled="False"
        CanUserReorderColumns="False"
        CanUserSearch="False"
        ShowGroupPanel="False">
        <telerik:RadGridView.Columns>
            <telerik:GridViewDataColumn
                DataMemberBinding="{Binding Text}"
                Header="Text"
                ShowDistinctFilters="False"
                IsSortable="False"/>
        </telerik:RadGridView.Columns>
    </telerik:RadGridView>

Nothing too fancy.

What we observe:

When a message is added, the view and the scroll indicator randomly jump to the top or the bottom of the grid and stay there until the next message is added.

We tried AddRange, Suspend-/ResumeNotifications, ObservableCollection instead of RadObservableCollection.

We disabled many grid features.

We tried .NetCore

,

we tried .net Framework

To no avail.

This seems to be a bug.

Do you know any workarounds or a completely different approach to achieve the desired behaviour?

Side note:

When we set GroupRenderingMode to Flat,

        GroupRenderMode="Flat"

the view stays at the bottom. The scroll indicator stays at the bottom as well, but once in a while jumps a little bit up, as if by one row, and down to the bottom again without the view changing.

At one time disabling filtering on all columns seemd to work... but later didn't.

Thanks in advance

Thorsten

When you have rows grouped by null value and you try to move one of the rows to another group, a NullReferenceException is thrown.

This is reproducible only when DataView is used as ItemsSource of RadGridView.

To work this around, avoid using null values. Or avoid using DataView.

The GroupRenderMode of the RadGridVIew is set to Flat. The control is populated with items that implement the IList interface. The Count property of the custom objects needs to return value bigger than 1. So when the Delete button is pressed, the rows beneath the deleted one will also be deleted. Their number depends on the Count property of the custom object.

Blank spaces where rows should appear are observed in the following situation. You start editing a row or a column, then scroll the row outside of the viewport before the edit was committed. Then sort a column.

This is reproducible only if the GroupRenderMode property of RadGridView is set to Flat. Also, the AutoGenerateColumns property should be set to False and the Columns should be added manually.

Note that the issue is reproducible also in RadTreeListView, which has the GroupRenderMode set to Flat by default.

To work this around, set the GroupRenderMode property of RadGridView to Nested.

* Workaround: commit the edit before removing the item
* Works fine with the old Nested mode