The TelerikCheckBoxListFilter starts working very slowly with hundreds of items or more. That includes rendering and searching in it.

A possible workaround is to put a virtual Grid inside the FilterMenuTemplate. The example below is a modified version of this one - Blazor Grid checkbox list filtering with custom data. The FilterMenuButtonsTemplate is necessary to clear the selected Grid rows when the user clears the column filter.

@using Telerik.DataSource
@using Telerik.DataSource.Extensions

<TelerikGrid TItem="@Employee"
             OnRead="@OnReadHandler"
             Pageable="true"
             FilterMode="@( NameOptions != null ? GridFilterMode.FilterMenu : GridFilterMode.None )"
             FilterMenuType="@FilterMenuType.CheckBoxList"
             Height="400px">
    <GridColumns>
        <GridColumn Field="@(nameof(Employee.EmployeeId))" Filterable="false" />
        <GridColumn Field="@nameof(Employee.Name)">
            <FilterMenuTemplate Context="context">
                <TelerikGrid Data="@NameOptions"
                             ScrollMode="@GridScrollMode.Virtual"
                             Height="240px"
                             RowHeight="36"
                             FilterMode="@GridFilterMode.FilterRow"
                             SelectionMode="@GridSelectionMode.Multiple"
                             SelectedItems="@SelectedGridItems"
                             SelectedItemsChanged="@( (IEnumerable<NameFilterOption> newSelected) =>
                                                      GridSelectedItemsChanged(newSelected, context.FilterDescriptor) )">
                    <GridColumns>
                        <GridCheckboxColumn SelectAllMode="@GridSelectAllMode.All" />
                        <GridColumn Field="@nameof(NameFilterOption.Name)"></GridColumn>
                    </GridColumns>
                </TelerikGrid>
            </FilterMenuTemplate>
            <FilterMenuButtonsTemplate Context="filterContext">
                <TelerikButton OnClick="@(async _ => await filterContext.FilterAsync())"
                               ThemeColor="@ThemeConstants.Button.ThemeColor.Primary">Filter </TelerikButton>
                <TelerikButton OnClick="@(() => ClearFilterAsync(filterContext))">Clear</TelerikButton>
            </FilterMenuButtonsTemplate>
        </GridColumn>
        <GridColumn Field="@nameof(Employee.Team)" Title="Team" />
        <GridColumn Field="@nameof(Employee.IsOnLeave)" Title="On Vacation" />
    </GridColumns>
</TelerikGrid>

@code {
    string DDLValue { get; set; }
    List<Employee> AllGridData { get; set; }

    private IEnumerable<NameFilterOption> SelectedGridItems { get; set; } = new List<NameFilterOption>();

    private void GridSelectedItemsChanged(IEnumerable<NameFilterOption> newSelectedItems, CompositeFilterDescriptor cfd)
    {
        SelectedGridItems = newSelectedItems;
        cfd.LogicalOperator = FilterCompositionLogicalOperator.Or;
        cfd.FilterDescriptors.Clear();
        foreach (var sgi in SelectedGridItems)
        {
            cfd.FilterDescriptors.Add(new FilterDescriptor()
            {
                Member = nameof(Employee.Name),
                MemberType = typeof(string),
                Operator = FilterOperator.IsEqualTo,
                Value = sgi.Name
            });
        }
    }

    private async Task ClearFilterAsync(FilterMenuTemplateContext filterContext)
    {
        SelectedGridItems = new List<NameFilterOption>();
        await filterContext.ClearFilterAsync();
    }

    #region custom-filter-data
    List<TeamNameFilterOption> TeamsList { get; set; }
    List<NameFilterOption> NameOptions { get; set; }

    //obtain filter lists data from the data source to show all options
    async Task GetTeamOptions()
    {
        if (TeamsList == null) // sample of caching since we always want all distinct options,
                               //but we don't want to make unnecessary requests
        {
            TeamsList = await GetNamesFromService();
        }
    }

    async Task<List<TeamNameFilterOption>> GetNamesFromService()
    {
        await Task.Delay(500);// simulate a real service delay

        // this is just one example of getting distinct values from the full data source
        // in a real case you'd probably call your data service here instead
        // or apply further logic (such as tie the returned data to the data the grid will have according to your business logic)
        List<TeamNameFilterOption> data = AllGridData.OrderBy(z => z.Team).Select(z => z.Team).
            Distinct().Select(t => new TeamNameFilterOption { Team = t }).ToList();

        return await Task.FromResult(data);
    }

    async Task GetNameOptions()
    {
        if (NameOptions == null)
        {
            NameOptions = await GetNameOptionsFromService();
        }
    }

    async Task<List<NameFilterOption>> GetNameOptionsFromService()
    {
        await Task.Delay(500);// simulate a real service delay

        List<NameFilterOption> data = AllGridData.OrderBy(z => z.Name).Select(z => z.Name).
            Distinct().Select(n => new NameFilterOption { Name = n }).ToList();

        return await Task.FromResult(data);
    }
    #endregion custom-filter-data

    async Task OnReadHandler(GridReadEventArgs args)
    {
        //typical data retrieval for the grid
        var filteredData = await AllGridData.ToDataSourceResultAsync(args.Request);
        args.Data = filteredData.Data as IEnumerable<Employee>;
        args.Total = filteredData.Total;
    }

    protected override async Task OnInitializedAsync()
    {
        // generate data that simulates the database for this example
        // the actual grid data is retrieve in its OnRead handler
        AllGridData = new List<Employee>();
        var rand = new Random();
        for (int i = 1; i <= 1000; i++)
        {
            AllGridData.Add(new Employee()
            {
                EmployeeId = i,
                Name = "Employee " + i.ToString(),
                Team = "Team " + i % 3,
                IsOnLeave = i % 2 == 0
            });
        }

        // get custom filters data. In a future version you will be able to call these methods
        // from the template initialization instead of here (or in OnRead) so that they fetch data
        // only when the user actually needs filter values, instead of always - that could improve server performance
        await GetTeamOptions();
        await GetNameOptions();
    }

    public class Employee
    {
        public int EmployeeId { get; set; }
        public string Name { get; set; }
        public string Team { get; set; }
        public bool IsOnLeave { get; set; }
    }

    // in this sample we use simplified models to fetch less data from the service
    // instead of using the full Employee model that has many fields we do not need for the filters

    public class TeamNameFilterOption
    {
        public string Team { get; set; }
    }

    public class NameFilterOption
    {
        public string Name { get; set; }
    }
}

The Grid PageSizes DropDownList will not select a new value if it the current value is not visible in the open dropdown. This can happen if there are too many items in the DropDownList and the user has scrolled the PageSizes dropdown.

The problem occurs only when Navigable="true".

Here is a REPL test page

The easiest workaround is to fewer items in the PageSizes DropDownList, so that there is no need for scrolling.

Hello everyone,

We created this Feature Request to gather feedback on the way the item expansion is working in the Grid state. Currently, you can expand any items with the ExpandedRows collection of int where you pass the indexes of the rows. 

Another option, which we are thinking of, is to provide a Collection<Model>. This would let you pass models, instead of indexes and the Grid would automatically expand those items. This approach would make the need to preserve the indexes redundant, which you should currently do when Filtering/Sorting and Grouping the items in the Grid.

We would appreciate your feedback on both approaches and which you think will be easier to use.

Hello,

after updating to the versin 4.6.0 from 4.5.0, almost all svg icons dissapeared(inside the grid). No erros, no console warnings.

Is there some breaking changes or aditional steps how to bring them back?

Original markup without changes(first blue button in example should have "play" icon at the beginning):

<TelerikButton OnClick="@(_ => OZRowCmd(null,20))" Icon="@FontIcon.Play" Title="Zahájit novou" Class="bg-primary" Size="@Telerik.Blazor.ThemeConstants.Button.Size.Large">Zahájit novou</TelerikButton>

Currently, if I call Grid.AutoFitAllColumnsAsync "too early" it throws a null reference exception.

I am aware that this is a limitation but the behavior can be improved. For example, handle the exception and provide some useful information or give me a programmatic way to know if it's too early to call autofit.

I have a Grid with TItem="Dictionary<string, object>". I am not able to programmatically set EditItem and EditField through state.

I tried saving the state while editing to ensure the EditItem and EditField will be properly stored. When I try to retrieve this state object afterwards nothing happens.

Reproduction: https://blazorrepl.telerik.com/GnvYaIbd19iOZ6GH08.

Hello,

in some cases there is no way to scroll grid using mousewheel. Try this REPL please - https://blazorrepl.telerik.com/GdkXuLuX10P8sOF040. Scroll down, focus any cell in the last row and try to scroll up using your mouse wheel again.  Grid always scrolls back to the last row.

Can you check that please?

Very thanks.

Miroslav

Using the following configuration does not produce the expected result:

 <GridSettings>
        <GridPopupEditFormSettings ButtonsLayout="FormButtonsLayout.Center"/>
 </GridSettings>

The button layout is always left no matter what you choose.

===

ADMIN EDIT

===

Possible workarounds for the time being are to position the buttons with CSS or use a Popup Buttons Template.

Hi

The reset button is not working when we use the column template with the Telerik grid. How to solve this problem? Can you please send it example for reference?

Example Link :

Working Without Column Template

=>https://demos.telerik.com/blazor-ui/grid/column-menu

Not Working With Column Template

=>https://demos.telerik.com/blazor-ui/grid/custom-column-menu

Thanks

When initial grouping is set through the state, the GroupFooterTemplate does not render. One has to perform some action for refreshing the Grid in order to display the template - for example, collapsing/expanding a group.

For reference, the GroupHeaderTemplate renders correctly.

Reproduction: https://blazorrepl.telerik.com/wRaJFgFy10vagYnf05

===

ADMIN EDIT

===

The GroupFooterTemplate renders with a delay after the Grid. A possible workaround for the time being is to refresh the Grid after it has been initialized to ensure the GroupFooterTemplate will be displayed.

Example: https://blazorrepl.telerik.com/mxkJvAbI17SoNaE148

When the Virtualization feature is enabled, triggering Incell edit causes the Grid to scroll. When we scroll the edit is canceled. This happens when the row is partially visible.
https://www.screencast.com/t/zCJ9z9P83c

A more specific case is when you try to edit the last row. In case the editor height is bigger than the row height the Grid tries to scroll but there is no more data. The editor is closed and the item cannot be edited.
https://www.screencast.com/t/331cT4xxt

Reproduction: https://blazorrepl.telerik.com/QxEcECvx22pq4BBG59

App just crashed with the below exception.  My code isn't in the stack trace. Chances are there is no proper validation on parameters, allowing me to supply bad data, which later causes this problem.  Please validate the data better, debugging these things is not easy.

Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware: Error: An unhandled exception has occurred while executing the request.

System.ArgumentNullException: Value cannot be null. (Parameter 'source')
   at System.Linq.ThrowHelper.ThrowArgumentNullException(ExceptionArgument argument)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
   at Telerik.Blazor.Components.TelerikGrid`1.SetProcessedData(IEnumerable data)
   at Telerik.Blazor.Components.Common.DataBoundComponent`1.ProcessDataSourceResult(DataSourceResult result)
   at Telerik.Blazor.Components.Common.GridBase`1.ProcessDataSourceResult(DataSourceResult result)
   at Telerik.Blazor.Components.Common.DataBoundComponent`1.ProcessDataInternal()
   at Telerik.Blazor.Components.TelerikGrid`1.ProcessDataInternal()
   at Telerik.Blazor.Components.Common.DataBoundComponent`1.OnParametersSetAsync()
   at Telerik.Blazor.Components.TelerikGrid`1.OnParametersSetAsync()
   at Microsoft.AspNetCore.Components.ComponentBase.CallStateHasChangedOnAsyncCompletion(Task task)
   at Microsoft.AspNetCore.Components.ComponentBase.RunInitAndSetParametersAsync()
   at Microsoft.AspNetCore.Components.Rendering.ComponentState.SetDirectParameters(ParameterView parameters)
   at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.InitializeNewComponentFrame(DiffContext& diffContext, Int32 frameIndex)
   at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.InitializeNewSubtree(DiffContext& diffContext, Int32 frameIndex)
   at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.InsertNewFrame(DiffContext& diffContext, Int32 newFrameIndex)
   at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.AppendDiffEntriesForRange(DiffContext& diffContext, Int32 oldStartIndex, Int32 oldEndIndexExcl, Int32 newStartIndex, Int32 newEndIndexExcl)
   at Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.ComputeDiff(Renderer renderer, RenderBatchBuilder batchBuilder, Int32 componentId, ArrayRange`1 oldTree, ArrayRange`1 newTree)
   at Microsoft.AspNetCore.Components.Rendering.ComponentState.RenderIntoBatch(RenderBatchBuilder batchBuilder, RenderFragment renderFragment, Exception& renderFragmentException)
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.ProcessRenderQueue()
--- End of stack trace from previous location ---
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.ProcessRenderQueue()
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.AddToRenderQueue(Int32 componentId, RenderFragment renderFragment)
   at Microsoft.AspNetCore.Components.ComponentBase.StateHasChanged()
   at Microsoft.AspNetCore.Components.ComponentBase.CallOnParametersSetAsync()
   at Microsoft.AspNetCore.Components.ComponentBase.RunInitAndSetParametersAsync()
   at Microsoft.AspNetCore.Components.Rendering.ComponentState.SetDirectParameters(ParameterView parameters)
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.RenderRootComponentAsync(Int32 componentId, ParameterView initialParameters)
   at Microsoft.AspNetCore.Components.Rendering.HtmlRenderer.RenderComponentAsync(Type componentType, ParameterView initialParameters)
   at Microsoft.AspNetCore.Components.Rendering.RendererSynchronizationContext.<>c__11`1.<<InvokeAsync>b__11_0>d.MoveNext()
--- End of stack trace from previous location ---
   at Microsoft.AspNetCore.Mvc.ViewFeatures.StaticComponentRenderer.PrerenderComponentAsync(ParameterView parameters, HttpContext httpContext, Type componentType)
   at Microsoft.AspNetCore.Mvc.ViewFeatures.ComponentRenderer.PrerenderedServerComponentAsync(HttpContext context, ServerComponentInvocationSequence invocationId, Type type, ParameterView parametersCollection)
   at Microsoft.AspNetCore.Mvc.ViewFeatures.ComponentRenderer.RenderComponentAsync(ViewContext viewContext, Type componentType, RenderMode renderMode, Object parameters)
   at Microsoft.AspNetCore.Mvc.TagHelpers.ComponentTagHelper.ProcessAsync(TagHelperContext context, TagHelperOutput output)
   at Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperRunner.<RunAsync>g__Awaited|0_0(Task task, TagHelperExecutionContext executionContext, Int32 i, Int32 count)
   at EnrichmentEngine.Pages.Pages__Host.<ExecuteAsync>b__15_1() in C:\Users\PeterDrier\source\repos\fleet\src\sovereign\dotnet\services\studio-calc-engine\SummaReportsPoc\Pages\_Host.cshtml:line 25
   at Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperExecutionContext.SetOutputContentAsync()
   at EnrichmentEngine.Pages.Pages__Host.ExecuteAsync() in C:\Users\PeterDrier\source\repos\fleet\src\sovereign\dotnet\services\studio-calc-engine\SummaReportsPoc\Pages\_Host.cshtml:line 7
   at Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderPageCoreAsync(IRazorPage page, ViewContext context)
   at Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderPageAsync(IRazorPage page, ViewContext context, Boolean invokeViewStarts)
   at Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderAsync(ViewContext context)
   at Microsoft.AspNetCore.Mvc.ViewFeatures.ViewExecutor.ExecuteAsync(ViewContext viewContext, String contentType, Nullable`1 statusCode)
   at Microsoft.AspNetCore.Mvc.ViewFeatures.ViewExecutor.ExecuteAsync(ViewContext viewContext, String contentType, Nullable`1 statusCode)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeResultAsync>g__Logged|22_0(ResourceInvoker invoker, IActionResult result)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResultFilterAsync>g__Awaited|30_0[TFilter,TFilterAsync](ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResultExecutedContextSealed context)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.ResultNext[TFilter,TFilterAsync](State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeResultFilters()
--- End of stack trace from previous location ---
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResourceFilter>g__Awaited|25_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResourceExecutedContextSealed context)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeFilterPipelineAsync()
--- End of stack trace from previous location ---
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Logged|17_1(ResourceInvoker invoker)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Logged|17_1(ResourceInvoker invoker)
   at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
   at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddlewareImpl.<Invoke>g__Awaited|8_0(ExceptionHandlerMiddlewareImpl middleware, HttpContext context, Task task)

By the following steps, the problem occurs:

1. Click on line number 1 to focus the row
2. Press the Down-Key 19 times to navigate to line 20
3. Try to navigate to line 21 via the Down-Key
4. -> No navigation possible via keyboard to the lines below
5. Try to navigate backwards via Up-Key to line 1
6. -> Navigation stops at line 15

So, it not possible to navigate through the whole grid with virtualized rows when Navigable=true





@* Scroll the grid instead of paging *@

<TelerikGrid Data=@GridData
             ScrollMode="@GridScrollMode.Virtual" Navigable="true"
             Height="480px" RowHeight="60" PageSize="20"
             Sortable="true" FilterMode="@GridFilterMode.FilterMenu">
    <GridColumns>
        <GridColumn Field="Id" />
        <GridColumn Field="Name" Title="First Name" />
        <GridColumn Field="LastName" Title="Last Name" />
        <GridColumn Field="HireData" Width="200px">
            <Template>
                @((context as SampleData).HireDate.ToString("MMMM dd, yyyy"))
            </Template>
        </GridColumn>
    </GridColumns>
</TelerikGrid>

@code {
    public List<SampleData> GridData { get; set; }

    protected override async Task OnInitializedAsync()
    {
        GridData = await GetData();
    }

    private async Task<List<SampleData>> GetData()
    {
        return Enumerable.Range(1, 1000).Select(x => new SampleData
        {
            Id = x,
            Name = $"name {x}",
            LastName = $"Surname {x}",
            HireDate = DateTime.Now.Date.AddDays(-x)
        }).ToList();
    }

    public class SampleData
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public string LastName { get; set; }
        public DateTime HireDate { get; set; }
    }
}