Questions on UI for ASP.NET Core Forum

0 answers

52 views

Kendo Form Tag Helper ignores <form-items> when placed inside a Partial View

Hello,

We are using Telerik UI for ASP.NET Core and have run into a limitation with the kendo-form tag helper. We would appreciate your guidance on how to resolve or work around it.

The Scenario

We have a form that operates in two modes—Create and Edit—using two different models. To avoid duplicating markup, we want to share the form field structure between both modes while dynamically switching the underlying data/model.

What We Tried

We extracted the <form-items> content into a shared partial view and attempted to include it inside the <kendo-form> tag helper using @await Html.PartialAsync("_FormFieldsPartial").

@if (Model.IsCreateMode)
{
    <kendo-form name="clientForm" form-data="Model.CreateData" method="post">
        @await Html.PartialAsync("_ApiClientFormFields")
        <validatable validation-summary="true" />
        <buttons-template>
            <button type="submit" class="k-button k-button-md k-rounded-md k-button-solid k-button-solid-primary">Create</button>
            <a href="/WebAPICredentials" class="k-button k-button-md k-rounded-md k-button-flat k-button-flat-base">Cancel</a>
        </buttons-template>
    </kendo-form>
}
else
{
    <kendo-form name="clientForm" form-data="Model.EditData" method="post">
        @await Html.PartialAsync("_ApiClientFormFields")
        <validatable validation-summary="true" />
        <buttons-template>
            <button type="submit" class="k-button k-button-md k-rounded-md k-button-solid k-button-solid-primary">Save</button>
            <a href="/WebAPICredentials" class="k-button k-button-md k-rounded-md k-button-flat k-button-flat-base">Cancel</a>
        </buttons-template>
    </kendo-form>
}

What We Observed

Observation 1 (Full Form): When the partial view contained the full form (11 fields using various editor tag helpers like textbox-editor, switch-editor, etc.), all 11 labels rendered on the page, but no input fields or widgets appeared.
Observation 2 (Stripped-Down Form): When we stripped the partial view down to just 5 basic fields using only textbox-editor, all 11 labels still rendered on the page, despite only 5 fields being defined in the partial.

Our Question

Is there a supported way to share <form-items> content across multiple <kendo-form> instances using partial views, or is this a known limitation of how the tag helper parses its child content?

If partial views are not supported for this use case, what alternative approach do you recommend to avoid duplicating 11+ fields across our Create and Edit views?

Thank you for your help.

Form

asked on 09 Jun 2026

1 answer

76 views

Auto Load Tab

I have a tabstrip in a view and I want the default tab to load automatically, Ive tried .Selected and as you can see .SelectedIndex but the tab is never selected or loaded. Surely there is a way to make it load without a bunch of javascript.

            <div class="col-9">
                @(Html.Kendo().TabStrip()
                    .Name("TabWorkflow")
                    .Animation(false)
                    .SelectedIndex(0)
                    .Items(tab =>
                    {
                        tab.Add().Text("Statuses").Enabled(Model.WorkflowId != 0).LoadContentFrom("Index", "WorkflowStatus", new { workflowId = Model.WorkflowId });
                    })
                )
            </div>

TabStrip

answered on 04 Jun 2026

1 answer

82 views

Telerik Grid Popup Custom Template Not working

I have a grid in where I added edit button that is connected to a custom template. When I click the button to edit fields for this row. It does not pop up my custom template but the default one with all the data. this is what I have:

@(
                    Html.Kendo().Grid(Model.GroupMemberships)
                    .Name("MemberGroupsGrid")

                    .Columns(columns =>
                    {
                        
                        columns.Template(
                        "# if (CanEdit) { #" +
                        "<a href='javascript:void(0)' name='expireDeleteLink' class='full-link w-100 h-100 d-flex align-items-center justify-content-center' " +
                        "title='Expire or Delete Member' " +
                        "onclick='openExpireDeleteModal(\"#= Id #\", \"#=GroupName#\", \"#=Name#\", \"#=IsExpired#\", \"" + Model.UserCanDeleteString + "\")'> " +
                        "<i class='fa-regular fa-trash-can text-danger' aria-hidden='true'></i>" +
                        "</a>" +
                        "# } #"
                        )
                        .Width(100)
                        .HtmlAttributes(new { @class = "text-center p-0 align-middle" })
                        .Media("(min-width: 850px)");
                        
                        columns.Command(command => command.Edit().Text(" ").IconClass(" fa-solid fa-user-pen text-secondary").HtmlAttributes(new { title = "Edit Member" }).Visible("CanEdit"));
                        columns.Bound(m => m.GroupId).Title("Group ID").Hidden(true).Exportable(false);
                        columns.Template("#=resColTemplate(data)#").Media("(max-width: 849px)");
                })
                .Pageable()
                .Editable(e => e.Mode(GridEditMode.PopUp).TemplateName("GroupMemberDetailTemplate").Window(w => w.Title("Member Group Details").Width(400).Height(300)))
                .Sortable()
                .Excel(excel => excel
                    .FileName("GroupMemberships.xlsx")
                    .Filterable(true)
                    .AllPages(true))
                .AutoBind(true)
                @* .Editable(e => e.Mode(GridEditMode.PopUp).TemplateName("MemberGroup")) *@
                .Events(ev => ev.Change("onChange").DataBound("onDataBound"))
                .HtmlAttributes(new { @class = "table table-hover align-middle" })
                .DataSource(dataSource => dataSource
                .Ajax()
                .ServerOperation(false)
                .Read(read => read.Action("GetGroupMemberships", "Members").Data("additionalData"))
                .PageSize(10)
                )
                )

this is the template

@model AMPS.Web.Models.MemberGroupsManagementPageModel.GroupMemberships
@{
}

<div class="row">
    <div class="col-md-6">
     @(Html.DisplayFor(model => model.MemberName)))
    </div>
 </div>

It is located in the ~Views/Shared/EditiorTemplates

General Discussions

Grid

answered on 22 May 2026

2 answers

102 views

Grid Validation Tooltip Styling

I have several grids with inline dropdown editors. The system users are complaining that the validation tooltips block the top options for the dropdown. Is there a way to specify that their position be placed at the top of the field rather than the bottom.

Grid

ToolTip

answered on 22 May 2026

2 answers

164 views

ASP.NET Core Upload control works but returns error

I'm attempting to use the Kendo Upload control asynchronously to an MVC controller, which passes the file to a WebApi controller. The file is uploaded successfully, however when it returns to the MVC view, it reports that the file failed to upload with the error below. We are using Azure B2C for authentication:

"Access to XMLHttpRequest at 'https... b2clogin.com...' (redirected from 'https//localhost:7074/Files/UploadFile') from origin 'https://localhost:7074' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource."

Server response:

"Failed to load resource: net::ERR_FAILED"

The control is located in a partial view as part of a tab control on a CSHTML view. Here is the code for the upload control:

<div class="row">
<div class="col-md-8">
@(Html.Kendo().Upload()
.Name("uploadedFile")
.Multiple(false)
.Validation(v =>
{
v.AllowedExtensions(new string[] { ".csv" });
v.MaxFileSize(3145728);
})
.Async(a => a
.AutoUpload(false)
.Save("UploadFile", "Files")
)
.Events(e =>
{
e.Upload("onFileUpload");
})

)
</div>
<div class="col-md-4">
</div>

</div>

Here is the C# code for the MVC controller:

[HttpPost]
public async Task<ActionResult> UploadFile(IFormFile uploadedFile, string month, string year)
{
if (uploadedFile == null || uploadedFile.Length == 0)
return BadRequest("No file uploaded.");

var reportingPeriod = month + year;

using (var content = new MultipartFormDataContent())
{
if (uploadedFile.Length > 0)
{
var streamContent = new StreamContent(uploadedFile.OpenReadStream());
streamContent.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue(uploadedFile.ContentType);
content.Add(streamContent, "file", uploadedFile.FileName);
}

using (var response = await _client.HttpClient.PostAsync("/api/Files/loadbackdatedmonthlytrueupfile/" + reportingPeriod, content))
{
if (response.IsSuccessStatusCode)
{
// Kendo expects an empty string for success
return Content("");
}
else
{
return StatusCode((int)response.StatusCode, await response.Content.ReadAsStringAsync());
}

}

}
}

Here is the code for the WebApi controller:

[HttpPost("loadbackdatedmonthlytrueupfile/{reportingPeriod}")]
public async Task<IActionResult> LoadBackdatedMonthlyTrueUpFile([FromForm] IFormFile file, string reportingPeriod)

{

//other logic here

return Ok(new { file.FileName, file.Length });

}

This is the info I received from Copilot:

This error is caused by trying to call the Azure AD B2C /authorize endpoint using an XMLHttpRequest (AJAX/fetch) from your frontend (https://localhost:7074). Azure AD B2C does not support CORS for this endpoint, so the browser blocks the request.
Root cause:
• The /authorize endpoint is designed for browser redirects, not AJAX/fetch/XHR.
• No CORS headers will ever be present on this endpoint, so preflight requests will always fail.
How to fix:
• Never use AJAX/fetch/XHR to call the /authorize endpoint.
• Always use a full-page redirect for authentication.
For example, set window.location.href to the login URL, or let the [Authorize] attribute and OIDC middleware handle it for you.

How can I configure this upload control to return to the view without the error (attaching screenshot)?

Upload

updated answer on 20 May 2026

1 answer

63 views

Make the Telerik Grid Client DetailTemplate Editable

I currently have a Grid that I want the ClientDetailTemplateId to be the editable area for fields that are currently not displayed on the grid. Then have an update button that uses the Datasource function of Update to update that row's values.

@( Html.Kendo().Grid(Model.Members)
                .Name("membersGrid")
                .Columns(columns =>
                {
                              
                        
                    })
                    .AutoBind(true)
                    .HtmlAttributes(new { @class = "table table-hover align-middle faux-k-table" , style =" width: 100%"})
                    .Pageable()
                    .Sortable(false)
                       .ClientDetailTemplateId("DetailGridTemplate")          
                    .DataSource(dataSource => dataSource
                        .Ajax()
                        .PageSize(50)
                                .Events(e =>  e.RequestStart("onRequestStart")
                                             .RequestEnd("onRequestEnd")
                                              )
                        .Read(read => read.Action("GetGroupMembers", "Members").Data("additionalData"))
                    ).NoRecords(n => n.Template(@"<div class=""alert alert-warning"">
                        No data found with selected filter values or there are no eligible members from your MEC to view.
                    </div>"))
                        )


script id="DetailGridTemplate" type="text/kendo-tmpl">

                     
</script>

General Discussions

Grid

answered on 15 May 2026

1 answer

59 views

[Solved] AppBar Tag Helper - how to apply primary theme color

Hi,

I'm using Telerik UI for ASP.NET Core with a custom theme exported from Theme Builder (Default base). The theme is loaded as a local CSS.

Theme
Custom Theme Builder export with a teal primary color.

Layout (`_Layout.cshtml`)

<head>
    <link rel="stylesheet" href="~/css/my-theme.v0.1.0.css" asp-append-version="true" />
    <script src="https://code.jquery.com/jquery-3.7.1.min.js"></script>
    <script src="https://cdn.kendostatic.com/2026.1.415/js/kendo.all.min.js"></script>
    <script src="https://cdn.kendostatic.com/2026.1.415/js/kendo.aspnetmvc.min.js"></script>
</head>
<body class="k-body k-bg-surface">
    <header>
        <kendo-appbar name="appBar">
            <items>
                <appbar-item type="AppBarItemType.ContentItem"
                    template="<a class='k-button k-button-flat' href='/Index'>Index</a>">
                </appbar-item>
            </items>
        </kendo-appbar>
    </header>
</body>

What works

The AppBar correctly changes background when switching between `AppBarThemeColor.Dark`, `AppBarThemeColor.Light`, and `AppBarThemeColor.Inherit`. The theme is loading and the component is initializing correctly.

Questions

1. Is there a way to apply `primary` as the AppBar theme color using the Tag Helper?

Thanks

AppBar

answered on 13 May 2026

2 answers

54 views

Keyboard trap

Keyboard trap. According the Telerik documentation a user should be able to use the keyboard to navigate out of the spreadsheet (https://www.telerik.com/aspnet-core-ui/documentation/html-helpers/data-management/spreadsheet/accessibility/keyboard-navigation), but I don’t see it working in their demo. Does anyone have any solutions for this bug?

Accessibility

answered on 11 May 2026

1 answer

38 views

Links in Grid Hierarchy

When a table element contains a link, mouse actions differ from keyboard navigation. Anyone have a work-around for this so that there is a keyboard equivalent to a mouse click action?

Accessibility

answered on 08 May 2026

1 answer

48 views

Keyboard accesibility

Does anyone know if there are any plans for custom cell editing (e.g., https://demos.telerik.com/aspnet-core/spreadsheet/custom-editors) and filtering (e.g., https://demos.telerik.com/aspnet-core/grid/filter-row) to be keyboard accessible?

Accessibility

answered on 08 May 2026