Declined
Last Updated: 25 Jan 2016 09:43 by ADMIN
If you refresh an object set property of entity context, the RadGridView is not updated. 

The sample code below does not work:

this.radGridView1.DataSource = entities.Countries;

int maxId = (from c in entities.Countries
                         orderby c.Id descending
                         select c.Id).First();

            Country country = new Country();
            country.Id = maxId + 1;
            country.Name = Path.GetRandomFileName();
            entities.Countries.AddObject(country);
            entities.SaveChanges(System.Data.Objects.SaveOptions.AcceptAllChangesAfterSave);

            entities.Refresh(System.Data.Objects.RefreshMode.StoreWins, entities.Countries);
Declined
Last Updated: 05 Jun 2015 08:32 by ADMIN
To reproduce:
void radGridView1_CurrentRowChanged(object sender, Telerik.WinControls.UI.CurrentRowChangedEventArgs e)
        {
            e.CurrentRow.Cells[2].ColumnInfo.IsCurrent = true;
        }
Declined
Last Updated: 25 Mar 2014 16:14 by ADMIN
To reproduce:
void grid_RowValidating(object sender, RowValidatingEventArgs e)
{
    e.Cancel = true;
}

Pressing the escape key should cancel the edit mode and revert the value
Declined
Last Updated: 16 May 2019 08:10 by ADMIN
- Create a new project containing RadGridView
- Build hierarchy with large text data in cells
- Set the AutoSizeRows property to true and AutoSizeColumnMode to Fill
- Run the project, scroll down and try to click on a cell
Declined
Last Updated: 05 Jun 2019 12:21 by ADMIN
Declined
Last Updated: 17 May 2017 05:15 by ADMIN
To reproduce: please refer to the attached sample project. 

Workaround:   this.radGridView1.TableElement.ScrollToRow(this.radGridView1.RowCount-1);
Declined
Last Updated: 27 Jun 2018 10:14 by ADMIN
I have a GridView (Winforms v. 2017.3.1017.40, same problem with 2017.2.502.40) configured as on the attached screenshot (made some groups, made a search, and used the "excel-like" filter on a column to uncheck some values).

Then I try to click on some column headers to sort the grid.
After a few clicks, I get this error :
InvalidOperationException: La collection a été modifiée ; l'opération d'énumération peut ne pas s'exécuter.

I got different stacktrace with the same error :
InvalidOperationException: La collection a été modifiée ; l'opération d'énumération peut ne pas s'exécuter.
   at System.ThrowHelper.ThrowInvalidOperationException(ExceptionResource resource)
   at System.Collections.Generic.List`1.Enumerator.MoveNextRare()
   at System.Collections.Generic.List`1.Enumerator.MoveNext()
   at Telerik.WinControls.UI.DataGroup.<GetEnumerator>d__0.MoveNext()
   at Telerik.WinControls.UI.GridViewGroupRowInfo.get_ChildRows()
   at Telerik.WinControls.UI.GridViewRowInfo.HasChildRows()
   at Telerik.WinControls.UI.PrintGridTraverser.CanStepInHierarchy()
   at Telerik.WinControls.UI.GridTraverser.StepInHierarchy()
   at Telerik.WinControls.UI.GridTraverser.MoveNextCore()
   at Telerik.WinControls.UI.GridTraverser.MoveNext()
   at Telerik.WinControls.UI.GridViewSearchRowInfo.worker_DoWork(Object sender, DoWorkEventArgs e)
   at System.ComponentModel.BackgroundWorker.OnDoWork(DoWorkEventArgs e)
   at System.ComponentModel.BackgroundWorker.WorkerThreadStart(Object argument)

-----

InvalidOperationException: Failed to compare two elements in the array. ---> NullReferenceException: Object reference not set to an instance of an object.
   at Telerik.WinControls.UI.GridViewRowInfoComparer.CompareRows(GridViewRowInfo x, GridViewRowInfo y, SortDescriptorCollection context)
   at System.Collections.Generic.ArraySortHelper`1.InternalBinarySearch(T[] array, Int32 index, Int32 length, T value, IComparer`1 comparer)
   at System.Collections.Generic.ArraySortHelper`1.BinarySearch(T[] array, Int32 index, Int32 length, T value, IComparer`1 comparer)


   --- End of inner exception stack trace ---
   at System.Collections.Generic.ArraySortHelper`1.BinarySearch(T[] array, Int32 index, Int32 length, T value, IComparer`1 comparer)
   at System.Collections.Generic.List`1.BinarySearch(Int32 index, Int32 count, T item, IComparer`1 comparer)
   at Telerik.Collections.Generic.HybridIndex`1.PerformWithQuickSort()
   at Telerik.Collections.Generic.HybridIndex`1.get_Items()
   at Telerik.Collections.Generic.Index`1.GetEnumerator()
   at Telerik.WinControls.Data.GroupBuilder`1.Perform(IReadOnlyCollection`1 items, Int32 level, Group`1 parent)
   at Telerik.WinControls.Data.GroupBuilder`1.get_Groups()
   at Telerik.WinControls.UI.GridViewInfo.Refresh()
   at Telerik.WinControls.UI.GridViewInfo.get_ChildRows()
   at Telerik.WinControls.UI.ViewInfoTraverser.SetCollectionForStage(Boolean initializeCollection)
   at Telerik.WinControls.UI.ViewInfoTraverser.ChangeCollectionForward()
   at Telerik.WinControls.UI.ViewInfoTraverser.MoveNextCore()
   at Telerik.WinControls.UI.ViewInfoTraverser.MoveNext()
   at Telerik.WinControls.UI.GridTraverser.MoveNextCore()
   at Telerik.WinControls.UI.GridTraverser.MoveNext()
   at Telerik.WinControls.UI.BaseGridNavigator.NavigateToRow(GridViewRowInfo row, Boolean select)
   at Telerik.WinControls.UI.BaseGridNavigator.ProcessViewChangedEvent(GridViewEvent eventData)
   at Telerik.WinControls.UI.BaseGridNavigator.ProcessEventCore(GridViewEvent eventData)
   at Telerik.WinControls.UI.GridViewEventProcessEntity.ProcessCollection(GridViewEvent gridEvent, PriorityWeakReferenceList list, GridEventProcessMode processMode)
   at Telerik.WinControls.UI.GridViewEventProcessEntity.ProcessEvent(GridViewEvent gridEvent)
   at Telerik.WinControls.UI.GridViewSynchronizationService.NotifyListeners(GridViewEvent gridEvent)
   at Telerik.WinControls.UI.GridViewSynchronizationService.FlushEvents()
   at Telerik.WinControls.UI.GridViewSynchronizationService.DispatchEvent(GridViewEvent gridEvent)
   at Telerik.WinControls.UI.GridViewSynchronizationService.DispatchEvent(GridViewTemplate template, GridViewEvent eventData, Boolean postUI)
   at Telerik.WinControls.UI.GridViewTemplate.DispatchDataViewChangedEvent(Object sender, DataViewChangedEventArgs args)
   at Telerik.WinControls.UI.GridViewTemplate.OnViewChanged(Object sender, DataViewChangedEventArgs e)
   at Telerik.WinControls.UI.MasterGridViewTemplate.OnViewChanged(Object sender, DataViewChangedEventArgs e)
   at Telerik.WinControls.Data.RadDataView`1.RebuildData(Boolean notify)
   at Telerik.WinControls.Data.RadDataView`1.OnNotifyPropertyChanged(PropertyChangedEventArgs e)
   at Telerik.WinControls.Data.RadCollectionView`1.OnNotifyPropertyChanged(String propertyName)
   at Telerik.WinControls.UI.GridViewSortDescriptorCollection.OnCollectionChanged(NotifyCollectionChangedEventArgs args)
   at System.ComponentModel.PropertyChangedEventHandler.Invoke(Object sender, PropertyChangedEventArgs e)
   at Telerik.WinControls.Data.SortDescriptor.set_Direction(ListSortDirection value)
   at Telerik.WinControls.UI.GridViewColumn.Sort(RadSortOrder sortOrder, Boolean multiSortMode)
   at Telerik.WinControls.UI.GridHeaderCellElement.Sort(RadSortOrder sortOrder)
   at Telerik.WinControls.UI.GridHeaderRowBehavior.OnMouseUp(MouseEventArgs e)
   at Telerik.WinControls.UI.BaseGridBehavior.OnMouseUp(MouseEventArgs e)
   at Telerik.WinControls.UI.RadGridView.OnMouseUp(MouseEventArgs e)
   at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at Telerik.WinControls.RadControl.WndProc(Message& m)
   at Telerik.WinControls.UI.RadGridView.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

------

InvalidOperationException: Collection was modified; enumeration operation may not execute.
   at System.ThrowHelper.ThrowInvalidOperationException(ExceptionResource resource)
   at System.Collections.Generic.List`1.Enumerator.MoveNextRare()
   at System.Collections.Generic.List`1.Enumerator.MoveNext()
   at Telerik.WinControls.UI.DataGroup.<GetEnumerator>d__0.MoveNext()
[...]
   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
   at Alto.Client.Controls.Dispatch.DispatchResources.DeliveryPointFilterManager.get_DeliveryPointsVisible() in d:\Builds\45153\Alto\Alto.Prod\src\Alto\Alto.Client\Controls\Dispatch\DispatchResources\DeliveryPointFilterManager.cs:line 38
   at Alto.Client.Controls.Dispatch.DispatchResources.UcDeliveryPoint.get_Title() in d:\Builds\45153\Alto\Alto.Prod\src\Alto\Alto.Client\Controls\Dispatch\DispatchResources\UcDeliveryPoint.cs:line 1520
   at Alto.Client.Controls.Dispatch.DispatchResources.UcDeliveryPoint.updatePanelTitle() in d:\Builds\45153\Alto\Alto.Prod\src\Alto\Alto.Client\Controls\Dispatch\DispatchResources\UcDeliveryPoint.cs:line 543
   at Alto.Client.Controls.Dispatch.DispatchResources.UcDeliveryPoint.onFilterChanged(Object sender, GridViewCollectionChangedEventArgs e) in d:\Builds\45153\Alto\Alto.Prod\src\Alto\Alto.Client\Controls\Dispatch\DispatchResources\UcDeliveryPoint.cs:line 547
   at Telerik.WinControls.UI.GridViewCollectionChangedEventHandler.Invoke(Object sender, GridViewCollectionChangedEventArgs e)
   at Telerik.WinControls.UI.RadGridView.OnFilterChanged(Object sender, GridViewCollectionChangedEventArgs e)
   at Telerik.WinControls.UI.EventDispatcher.RaiseEvent[T](Object eventKey, Object sender, T args)
   at Telerik.WinControls.UI.GridViewFilterDescriptorCollection.OnCollectionChanged(NotifyCollectionChangedEventArgs args)
   at Telerik.Collections.Generic.NotifyCollection`1.InsertItem(Int32 index, T item)
   at Telerik.WinControls.UI.GridViewFilterDescriptorCollection.InsertItem(Int32 index, FilterDescriptor item)
   at System.Collections.ObjectModel.Collection`1.Add(T item)
   at Telerik.WinControls.UI.GridViewDataColumn.SetFilterDescriptor(FilterDescriptor value)
   at Telerik.WinControls.UI.GridHeaderCellElement.filterPopup_FilterConfirmed(Object sender, EventArgs e)
   at Telerik.WinControls.UI.BaseFilterPopup.OnFilterConfirmed()
   at Telerik.WinControls.UI.RadListFilterPopup.OnButtonOkClick(EventArgs e)
   at Telerik.WinControls.UI.RadListFilterPopup.ButtonOK_Click(Object sender, EventArgs e)
   at Telerik.WinControls.RadElement.OnClick(EventArgs e)
   at Telerik.WinControls.UI.RadButtonItem.OnClick(EventArgs e)
   at Telerik.WinControls.UI.RadButtonElement.OnClick(EventArgs e)
   at Telerik.WinControls.RadElement.DoClick(EventArgs e)
   at Telerik.WinControls.RadElement.RaiseBubbleEvent(RadElement sender, RoutedEventArgs args)
   at Telerik.WinControls.RadItem.RaiseBubbleEvent(RadElement sender, RoutedEventArgs args)
   at Telerik.WinControls.RadElement.RaiseRoutedEvent(RadElement sender, RoutedEventArgs args)
   at Telerik.WinControls.RadElement.RaiseBubbleEvent(RadElement sender, RoutedEventArgs args)
   at Telerik.WinControls.RadItem.RaiseBubbleEvent(RadElement sender, RoutedEventArgs args)
   at Telerik.WinControls.RadElement.RaiseRoutedEvent(RadElement sender, RoutedEventArgs args)
   at Telerik.WinControls.RadElement.DoMouseUp(MouseEventArgs e)
   at Telerik.WinControls.ComponentInputBehavior.OnMouseUp(MouseEventArgs e)
   at Telerik.WinControls.RadControl.OnMouseUp(MouseEventArgs e)
   at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.ScrollableControl.WndProc(Message& m)
   at Telerik.WinControls.RadControl.WndProc(Message& m)
   at Telerik.WinControls.UI.RadPopupControlBase.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

----

InvalidOperationException: Collection was modified; enumeration operation may not execute.
   at System.Collections.Generic.List`1.Enumerator.MoveNextRare()
   at Telerik.WinControls.UI.DataGroup.<GetEnumerator>d__0.MoveNext()
   at Telerik.WinControls.Data.GroupBuilder`1.Perform(IReadOnlyCollection`1 items, Int32 level, Group`1 parent)
   at Telerik.WinControls.Data.DataItemGroup`1.get_Groups()
   at Telerik.WinControls.UI.DataGroup.get_Groups()
   at Telerik.WinControls.UI.GridViewTemplate.InvalidateSummaryRowsCore(DataGroup group, Boolean invalidateChildren)
   at Telerik.WinControls.UI.GridViewTemplate.InvalidateSummaryRowsCore(DataGroup group, Boolean invalidateChildren)
   at Telerik.WinControls.UI.GridViewTemplate.InvalidateGroupSummaryRows(DataGroup group, Boolean invalidateChildren)
   at Telerik.WinControls.UI.GridViewTemplate.RefreshSummaryRowsInGroup(NotifyCollectionChangedEventArgs e)
   at Telerik.WinControls.UI.GridViewTemplate.RefreshAggregates(NotifyCollectionChangedEventArgs e)
   at Telerik.WinControls.UI.MasterGridViewTemplate.OnViewChanged(Object sender, DataViewChangedEventArgs e)
   at Telerik.WinControls.Data.RadDataView`1.RebuildData(Boolean notify)
   at Telerik.WinControls.Data.RadDataView`1.OnNotifyPropertyChanged(PropertyChangedEventArgs e)
   at Telerik.WinControls.Data.RadCollectionView`1.OnNotifyPropertyChanged(String propertyName)
   at Telerik.WinControls.UI.GridViewSortDescriptorCollection.OnCollectionChanged(NotifyCollectionChangedEventArgs args)
   at Telerik.WinControls.UI.GridViewSortDescriptorCollection.RemoveItem(Int32 index)
   at Telerik.WinControls.UI.GridViewColumn.Sort(RadSortOrder sortOrder, Boolean multiSortMode)
   at Telerik.WinControls.UI.GridHeaderCellElement.Sort(RadSortOrder sortOrder)
   at Telerik.WinControls.UI.GridHeaderRowBehavior.OnMouseUp(MouseEventArgs e)
   at Telerik.WinControls.UI.BaseGridBehavior.OnMouseUp(MouseEventArgs e)
   at Telerik.WinControls.UI.RadGridView.OnMouseUp(MouseEventArgs e)
   at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at Telerik.WinControls.RadControl.WndProc(Message& m)
   at Telerik.WinControls.UI.RadGridView.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

Declined
Last Updated: 25 Jun 2018 13:03 by ADMIN
To reproduce: please refer to the attached sample project. Note that the CellValidating event is fired twice even without showing a RadMessageBox. With an MS Button the problem is not reproducible.

Workaround: use the RadGridView.ValueChanging event to perform validation while the user is typing in the active editor:
 private void radGridView1_ValueChanging(object sender, Telerik.WinControls.UI.ValueChangingEventArgs e)
 {
   if (((string)e.NewValue) != "x")
     {
         RadMessageBox.Show("Only 'x' allowed!");
         e.Cancel = true;
     }
 }

Declined
Last Updated: 19 Aug 2016 11:44 by ADMIN
When you set a RadGridView's SelectionMode to GridViewSelectionMode.CellSelect and then you highlight full rows by using the row header, the SelectedRows collection is empty.  Telerik support informed me this is "as expected" and that I should use "SelectedCells" collection when using the CellSelect Mode.  While this is a decent workaround I don't see why SelectedRows collection can't be filled when the entire row is actually highlighted.  
Declined
Last Updated: 20 Feb 2014 09:51 by ADMIN
Steps to reproduce:
1. Add a grid to a form and make it read only
2. Add a masked box column and set the mask
3. Add some data and run the project
You will see that the mask is not applied to the values in the mask box column
Comment: This is not an issue.  The mask is applied after editing the text with RadMaskedEditBox, in read-only mode there is no masked editor created. You should use the conversion layer in RadGridView to solve the issue. Check the GridView >> Manipulated Data >> Convert Values example from our demo application.
Declined
Last Updated: 12 Sep 2015 08:55 by ADMIN
1. Create a new project with RadGridView.
2. Bind it and set grouping.
3. Add a summary row and set ShowParentGroupSummaries property to true.
4. Handle the ViewCellFormatting event and set all summary rows to be IsVisible = false when the processed cell is GridSummaryCellElement:

void radGridView1_ViewCellFormatting(object sender, CellFormattingEventArgs e)
{
    if (e.CellElement is GridSummaryCellElement)
    {
        e.Row.IsVisible = false;
    }
}

CORRECT WAY TO HANDLE THIS CASE:
Hide the summary rows in the groups you want after grouping/data binding.
To hide the first bottom summary row of the first group in a RadGridView use the following code:
this.radGridView1.Groups[0].GroupRow.BottomSummaryRows[0].IsVisible = false;
Declined
Last Updated: 31 Mar 2014 10:12 by ADMIN
ADMIN
Created by: Dess | Tech Support Engineer, Sr.
Comments: 1
Category: GridView
Type: Bug Report
2
To reproduce:
- add RadGridView and fill it with data;
- use the following code for saving the layout: string layout;
using (MemoryStream ms = new MemoryStream())
{
    radGridView1.SaveLayout(ms);
    ms.Position = 0;
    byte[] buffer = new byte[ms.Length - 1];

    ms.Read(buffer, 0, buffer.Length);
    layout = Convert.ToBase64String(buffer);
    ms.Close();
}

When you try to load the saved layout, using the following code, DataException is thrown:
using (MemoryStream stream = new MemoryStream(Convert.FromBase64String(layout)))
{
    radGridView1.LoadLayout(stream);
}

Workaround: save the layout in xml file
Declined
Last Updated: 14 Dec 2015 14:35 by ADMIN
The control just does not appear in the destination solution.
Declined
Last Updated: 15 Sep 2015 13:42 by ADMIN
If RadGridView is bound to custom objects that implement IComparable<T>, Excel-like filtering does not work. Currently, the issue can be avoided through implementing IComparable instead.
Declined
Last Updated: 22 Jul 2015 11:04 by ADMIN
The RadGridView should not leave its edit mode state, when scrolling is performed.
Declined
Last Updated: 03 Nov 2014 16:14 by ADMIN
This is not considered an issue, it is how RadGridView works. Here are more details:

In order for a GridDetailViewCellElement  to display a pageview instead of a single table element, either the template of the row holding it has to have more than one child template, or its ShowChildViewCaptions should be true.
Once there is a page view, the tabs in it will be visible at all times, except when some of the templates has no rows and AllowAddNewRow for it is false – if it does not have any rows and the user cannot add row, it is considered that there is no need from it.
If one needs to change the visibility of the tabs, this can be done in the ViewCellFormatting event:
private void RadGridView1_ViewCellFormatting(object sender, CellFormattingEventArgs e)
{
	GridDetailViewCellElement detailCell = e.CellElement as GridDetailViewCellElement;

	if (detailCell != null) {
		foreach (RadPageViewItem item in detailCell.PageViewElement.Items) {
			item.Visibility = Telerik.WinControls.ElementVisibility.Visible;
		}
	}
}
Declined
Last Updated: 15 Oct 2015 11:04 by ADMIN
To reproduce: 
1. Add GridView which inherits the RadGridView
2. Populate the grid with some data
3. Add conditional formatting and set RowBackColor and CellBackColor 
4. Subscribe to RowFormatting event and change the font of selected row: 
void radGridView2_RowFormatting(object sender, RowFormattingEventArgs e)
{
    if (e.RowElement.IsSelected)
    {
        e.RowElement.Font = new Font(this.Font.FontFamily, this.Font.Size + 2, FontStyle.Bold);
    }
    else
    {
        e.RowElement.ResetValue(LightVisualElement.FontProperty, ValueResetFlags.Local);
        //e.RowElement.Font = this.Font;
    }
}

5. Select row with conditional formatting. The font of selected row is bold which is correct. Select another row and you will see that the previous row is still bold.

Workaround: 
Subscribe to CellFormatting event instead RowFormatting
void radGridView2_CellFormatting(object sender, CellFormattingEventArgs e)
{
    if (e.Row.IsSelected)
    {
        e.CellElement.Font = new Font(this.Font.FontFamily, this.Font.Size + 2, FontStyle.Bold);
    }
    else
    {
        e.CellElement.ResetValue(LightVisualElement.FontProperty, ValueResetFlags.Local);
    }
}
Declined
Last Updated: 24 Aug 2015 13:05 by ADMIN
DECLINED: This happens because you are setting a non-image value to a GridViewImageColumn. The GridViewImageColumn is designed to work with image data directly and if any non-image data is used with this column, this will result in a large number of internal exceptions which are thrown while the column tries to read the image. The throw operation is an expensive one and this causes the slowdown. Also, note that the slowdown is much heavier when running the application with the debugger attached, because when this is the case, each internally thrown exception is written to the console, and writing to the console is an even more expensive operation. 

If the image is to be applied on the CellFormatting event and the value of the cells in a column are not going to be images, then GridViewTextBoxColumn should be used instead.

To reproduce: add a RadGridView and an  ImageList with two images. Use the following code snippet:

public Form1()
{
    InitializeComponent();

    DataTable dt = new DataTable();
    for (int i = 0; i < 10; i++)
    {
        dt.Columns.Add("Pic" + i);
    }
    
    for (int i = 0; i < 100; i++)
    {
        DataRow newRow = dt.NewRow();
        foreach (DataColumn col in dt.Columns)
        {
            newRow[col.ColumnName] = i;
        }
        dt.Rows.Add(newRow);
    }
    radGridView1.AutoGenerateColumns = false;
    
    for (int i = 0; i < 10; i++)
    {
        GridViewImageColumn imgCol = new GridViewImageColumn("col" + i);
        imgCol.Width = 100;
        imgCol.FieldName = "Pic" + i;
        this.radGridView1.Columns.Add(imgCol);
    }

    this.radGridView1.DataSource = dt;

    this.radGridView1.CellFormatting += radGridView1_CellFormatting;
}

private void radGridView1_CellFormatting(object sender, CellFormattingEventArgs e)
{
    if (e.Row is GridViewDataRowInfo)
    {
        e.CellElement.Image = this.imageList1.Images[e.RowIndex % 2];
    }
}
Declined
Last Updated: 12 Dec 2015 11:58 by ADMIN
How to handle this case:

Subscribe to the CellValidating event and add logic for validation. For example:

If e.Value Is Nothing Then
    e.Cancel = True
End If

Additionally you can handle the DataError event to handle cases where users are trying to submit invalid data through the grid to its data source.

Finally, you can subscribe to the ContextMenuOpening event where to hide the "Clear value" item from context menu with following code snippet:

For i As Integer = 0 To e.ContextMenu.Items.Count - 1
    If e.ContextMenu.Items(i).Text = "Clear Value" Then
        e.ContextMenu.Items(i).Visibility = Telerik.WinControls.ElementVisibility.Collapsed
    End If
Next
Declined
Last Updated: 10 Apr 2015 07:46 by ADMIN
Steps to reproduce:
1) Add RadGridView control
2) Add GridViewTextBoxColumn
2) Enable filtering: 

            this.radGridView1.EnableFiltering = true;

3) Programmatically set filter descriptor:

            FilterDescriptor filter = new FilterDescriptor();
            filter.PropertyName = "TextBoxColumn";
            filter.Operator = FilterOperator.IsEqualTo;
            filter.IsFilterEditor = true;
            
            this.radGridView1.FilterDescriptors.Add(filter);

Expected result: the default FilterDescriptor is changed from Contains to IsEqual
Actual result: can not set the default FilterDescriptor from Contains to IsEqual operator to a TextBoxColumn

Workaround:

        private void OnFilterExpressionChanged(object sender, FilterExpressionChangedEventArgs e)
        {
            GridViewTemplate owner = sender as GridViewTemplate;
            List<string> filterExpressions = new List<string>();

            for (int i = 0; i < owner.FilterDescriptors.Count; i++)
            {
                FilterDescriptor descriptor = owner.FilterDescriptors[i];
                string expression = null;

                CompositeFilterDescriptor compositeFilterDescriptor = descriptor as CompositeFilterDescriptor;

                if (compositeFilterDescriptor != null)
                {
                    foreach (FilterDescriptor filterDescriptor in compositeFilterDescriptor.FilterDescriptors)
                    {
                        if (string.IsNullOrEmpty(filterDescriptor.PropertyName) ||
                            owner.Columns[filterDescriptor.PropertyName] == null)
                        {
                            continue;
                        }
                    }

                    expression = CompositeFilterDescriptor.GetCompositeExpression(compositeFilterDescriptor);
                }
                else
                {
                    if (string.IsNullOrEmpty(descriptor.PropertyName) ||
                        owner.Columns[descriptor.PropertyName] == null)
                    {
                        continue;
                    }

                    if (descriptor.Value == null && (descriptor.Operator == FilterOperator.IsNotEqualTo || descriptor.Operator == FilterOperator.IsEqualTo))
                    {
                        expression = string.Empty;
                    }
                    else
                    {
                        expression = descriptor.Expression;
                    }
                }

                if (!string.IsNullOrEmpty(expression))
                {
                    filterExpressions.Add(expression);
                }
            }

            string logicalOperator = (owner.FilterDescriptors.LogicalOperator == FilterLogicalOperator.And) ? " AND " : " OR ";
            string resultExpression = String.Join(logicalOperator, filterExpressions.ToArray());
            e.FilterExpression = resultExpression;
        }
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