or
1 answer
54 views
The Dropdownlist has an Open method to open it programatically, the DropdownButton has no such functionality.
Hristian Stefanov
Telerik team
answered
on
30 Oct 2025
1 answer
48 views
Hi there
I'm trying to use DropDownlist with the Grouping field and the OnReadEvent, with mode = DropDownScrollMode.Scrollable
The OnRead event provides the grouping field to the request. The request is sent to my (API) server that handles the request, and the result is returned . Then after my OnReadHandler method ands, I get an internal exception: "System.NullReferenceException: 'Object reference not set to an instance of an object.'"
with following stack:
Telerik.Blazor.dll!Telerik.Blazor.Components.Common.TelerikSelectBase<SNG.LccNion.API.Model.Dto.IDDescriptiveDto, string>.ProcessGroupData(System.Collections.IEnumerable data) Unknown
Telerik.Blazor.dll!Telerik.Blazor.Components.Common.TelerikSelectBase<SNG.LccNion.API.Model.Dto.IDDescriptiveDto, string>.SetProcessedData(System.Collections.IEnumerable data) Unknown
Telerik.Blazor.dll!Telerik.Blazor.Components.TelerikDropDownList<SNG.LccNion.API.Model.Dto.IDDescriptiveDto, string>.SetProcessedData(System.Collections.IEnumerable data) Unknown
Telerik.Blazor.dll!Telerik.Blazor.Components.Common.DataBoundComponent<SNG.LccNion.API.Model.Dto.IDDescriptiveDto>.ProcessOnReadResult(Telerik.Blazor.Components.ReadEventArgs args) Unknown
Telerik.Blazor.dll!Telerik.Blazor.Components.Common.TelerikSelectBase<SNG.LccNion.API.Model.Dto.IDDescriptiveDto, string>.ProcessOnReadResult(Telerik.Blazor.Components.ReadEventArgs args) Unknown
Telerik.Blazor.dll!Telerik.Blazor.Components.Common.DataBoundComponent<SNG.LccNion.API.Model.Dto.IDDescriptiveDto>.ProcessOnReadData() Unknown
[Resuming Async Method]
> System.Private.CoreLib.dll!System.Runtime.CompilerServices.AsyncTaskMethodBuilder<System.Threading.Tasks.VoidTaskResult>.AsyncStateMachineBox<Telerik.Blazor.Components.Common.DataBoundComponent<SNG.LccNion.API.Model.Dto.IDDescriptiveDto>.<ProcessOnReadData>d__39>.ExecutionContextCallback(object s) Line 292 C#
System.Private.CoreLib.dll!System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, object state) Line 179 C#
System.Private.CoreLib.dll!System.Runtime.CompilerServices.AsyncTaskMethodBuilder<System.Threading.Tasks.VoidTaskResult>.AsyncStateMachineBox<Telerik.Blazor.Components.Common.DataBoundComponent<SNG.LccNion.API.Model.Dto.IDDescriptiveDto>.<ProcessOnReadData>d__39>.MoveNext(System.Threading.Thread threadPoolThread) Line 372 C#
System.Private.CoreLib.dll!System.Runtime.CompilerServices.AsyncTaskMethodBuilder<System.Threading.Tasks.VoidTaskResult>.AsyncStateMachineBox<Telerik.Blazor.Components.Common.DataBoundComponent<System.__Canon>.<ProcessOnReadData>d__39>.MoveNext() Line 350 C#
System.Private.CoreLib.dll!System.Runtime.CompilerServices.TaskAwaiter.OutputWaitEtwEvents.AnonymousMethod__12_0(System.Action innerContinuation, System.Threading.Tasks.Task innerTask) Line 281 C#
System.Private.CoreLib.dll!System.Threading.Tasks.AwaitTaskContinuation.RunCallback(System.Threading.ContextCallback callback, object state, ref System.Threading.Tasks.Task currentTask) Line 697 C#
System.Private.CoreLib.dll!System.Threading.Tasks.Task.RunContinuations(object continuationObject) Line 3486 C#
System.Private.CoreLib.dll!System.Runtime.CompilerServices.AsyncTaskMethodBuilder<Telerik.Blazor.Components.ReadEventArgs>.SetResult(Telerik.Blazor.Components.ReadEventArgs result) Line 478 C#
[Completed] Telerik.Blazor.dll!Telerik.Blazor.Components.TelerikDropDownList<SNG.LccNion.API.Model.Dto.IDDescriptiveDto, string>.TriggerReadAsync(Telerik.DataSource.DataSourceRequest request) Unknown
I am struggling to handle the request correctly and provide an answer back to the list that it can handle properly.
Nevertheless I get errors. Is there a working example of using the OnRead event with the GroupField property set to a property of the TItem? Or is this combination impossible inspite of DropDownScrollMode.Scrollable mode?
BTW - In case of large dropdownlist result set I want to fall back to virtual mode, and drop the grouping option, as it is documented that these are not compatible. (This is handled blazor side by checking the dataset count before the first OnRead call)
Ivan Danchev
Telerik team
answered
on
30 Oct 2025
0 answers
62 views
Currently it displays a long datetime string (day name, day of month number, month number, year), which is not user friendly for the intended users of my application. Is it posible to change this to another format, such as (day of month number, month number, year)?
1 answer
156 views
I've tried to find documentation on how to modify the CSS for the dropdownlist and it's popup but can't seem to figure out how to change the "Search" area size, nor the "Select Type" (they are too large).
I was able to figure out how to adjust the actual items:
.custom-compact-dropdownlist-popup .k-list-item {
padding-top: 2px;
padding-bottom: 2px;
font-size: 0.90em;
}
and reference:
<DropDownListSettings>
<DropDownListPopupSettings Class="custom-compact-dropdownlist-popup" />but I don't know what to use in CSS ... is there a list somewhere of the ".k" class selectors?
Rob.
Dimo
Telerik team
answered
on
27 Oct 2025
1 answer
73 views
Is it possible to change the headings in the column chooser menu?
This is supported in other Telerik products by using the Messages property which is absent in Blazor
1 answer
96 views
I'm looking at ThemeBuilder Ultimate for use in my Blazor-Server UI project. I went thru the 3 year old intro video but it's very out dated and seems to focus on Kendo UI. There is no mention on how to get a ThemeBuilder project into an existing Blazor UI project?
Also, I assume ThemeBuilder Pro/Ultimate are separate subscriptions from my existing Blazor UI Complete subscription? Your pricing material seems a bit confusing:
Why list Theme Builder ultimate under DevCraft Complete if it's not actually included in the DevCraft Complete subscription?
Theme builder looks to be a nice powerful and easy to use UI tool so I'd like more information before I make funding requests.
Rob.
Dimo
Telerik team
answered
on
23 Oct 2025
1 answer
83 views
In my _Host.cshtml:
<link href="_content/Telerik.UI.for.Blazor/css/kendo-theme-material/all.css?@telerikUiForBlazorVersion" rel="stylesheet" />In my page code:
<TelerikGrid TItem="@BookingModel"
@ref="@BookingGridRef"
Height="225px"
Resizable="false"
FilterMode="Telerik.Blazor.GridFilterMode.FilterMenu"
SelectionMode="GridSelectionMode.Single"
SelectedItems="@SelectedBookings"
OnRowClick="@OnBookingRowClick"
OnRowDoubleClick="@OnBookingRowDoubleClick"
OnRead="@OnBookingGridRead"
Sortable="true"
Reorderable="true"
Pageable="true"
@bind-Page="@CurrentBookingGridPage"
EnableLoaderContainer="false"
Size="@ThemeConstants.Grid.Size.Small"
PageSize="25">Setting the Size has no impact on the UI (Small, or Medium, or Large) renders the same.
In addition, setting RowHeight to a value has no impact on the UI:
<TelerikGrid TItem="@BookingModel"
@ref="@BookingGridRef"
Height="225px"
Resizable="false"
FilterMode="Telerik.Blazor.GridFilterMode.FilterMenu"
SelectionMode="GridSelectionMode.Single"
SelectedItems="@SelectedBookings"
OnRowClick="@OnBookingRowClick"
OnRowDoubleClick="@OnBookingRowDoubleClick"
OnRead="@OnBookingGridRead"
Sortable="true"
Reorderable="true"
Pageable="true"
@bind-Page="@CurrentBookingGridPage"
EnableLoaderContainer="false"
RowHeight="(decimal)12.5"
PageSize="25">It doesn't seem to matter what Theme I use in the _Host.cshtml file, RowHeight and Size are completely ignored?
Ultimately what I would like is to augment and Telerik theme with just a few changes, but I can't see any way to achieve this without going down the entire custom theme route, which I really don't have time for.
Rob.
Dimo
Telerik team
answered
on
23 Oct 2025
2 answers
149 views
Hi,
Is it possible to get event when user click/double click task on Gantt chart (grid/timeline). We should update some properties based on selected task.
Is it possible to create new dialog for popup editing?
1 answer
190 views
With the upcoming release of .net 10 which now provides the ability to pause and resume circuits will controls be updated to handle the pause and resume. Right now it feels like some javascript or interop is being called on resume for controls that arent part of the dom yet, im not exactly sure. Scheduler is one control in particular that we are experiencing issues with on Blazor.resumeCircuit(). If we change views and then pause or have an appointment window open we get the following Error: System.ArgumentException: There is no tracked object with id '13'
Dimo
Telerik team
answered
on
13 Oct 2025
1 answer
89 views
Hello,
Would it be possible to provide a clear set of steps—or ideally, a sample solution—demonstrating how to integrate Telerik Blazor with ASP.NET Identity using the .NET 9.0 framework? This seems like a fairly common requirement, but I haven’t been able to find any concise documentation that outlines the process.
I’ve created my project using the Blazor Web App template with Individual Accounts, and I’d like to confirm whether those settings are correct, and specifically, what additional steps are required to complete the integration such as changes to the Identity layout or pages (eg, Login.razor).
Thanks,
Kevin
Dimo
Telerik team
answered
on
10 Oct 2025
