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UI for ASP.NET Core Forum
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We need your feedback, because we are considering changes in the release approach for Telerik UI for ASP.NET Core. Please provide your feedback in the comments section below:


1. Is it hard to understand the version numbers of our releases? If yes, what makes them hard to understand them?

2. Would semantic versioning (SemVer) of our releases make it easier to understand our version numbers and what's behind them?

3. If we go with SemVer, we might need to start with version 3000.0.0 as we currently use 2022.x.x. Please share your thoughts about this approach and ideas for what number versioning would work best for you.

Chris
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 answered on 05 Feb 2024
1 answer
555 views

Hi!

The ListView is breaking my web application, and I cannot make head or tail of the reason:

An unhandled exception occurred while processing the request.

NotSupportedException: "ClientTemplateId or ClientTemplateHandler" cannot be null or empty.

Kendo.Mvc.UI.ListView<T>.VerifySettings()

 

Also, you demos for the ListView are broken and the browser tab crashed after a while.

I need an urgent fix, as this is affecting the live application.

Aleksandar
Telerik team
 answered on 17 Mar 2023
2 answers
95 views

when am used DropDownTree control i am used below sample format

@(Html.Kendo().DropDownTree()
       .Name("ID")
       .Label(label =>
       {
           label.Content("Select an ID...");
       })
       .DataTextField("Name")
       .DataValueField("id").Value(12)
       .HtmlAttributes(new { style = "width: 100%" })
       .Filter(FilterType.Contains)
       //.LoadOnDemand(true)
       .DataSource(dataSource => dataSource.ServerFiltering(true).Read(read => read.Action("GetLocationListForDDTree", "Home") ) )
   )

when enable loadondemand it works filter but value not show selected . if am command the loadondemand its show the selected value but filter not working . i need both options kindly advice this 

 

Saranya
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 answered on 12 Mar 2026
5 answers
365 views

Hello,

is there a possibility to support multitouch input on Pdf Viewer and Image Editor?

Moving and tapping is supported. So I can scroll through the pages for example. But I need to use zoom and pinch gesture for zooming in or out to documents / images also.

As we need to zoom just areas (e.g. maps with geo information) and keep the menus on top, the pages are not user-scalable as a whole:
<meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1,minimum-scale=1, user-scalable=no,text/html,charset=utf-8">

Is there any workaround to catch the event and set the zoom factor?

And is there a possibility to couple the mouse wheel / double click event to the zoom factor?

Thanks,

Christine

Marc
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Iron
 answered on 03 Mar 2026
1 answer
28 views

I am attempting to reference some CheckBoxes withing a RadGrid inside a PlaceHolder.

I have a field that I am retrieving called Block that contains a numerice value. Based on the value I am dynamically creating a number of CheckBoxes in a PlaceHolder equal to that value. I have a Button Click method that is trying to reference the CheckBoxes but it is not working correctly.

This line : Dim BlockCheckBox As CheckBox = DirectCast(phBlocksCheckBox.FindControl("BlockCheckBox_" & cbIndex), CheckBox) is not returning a value.

aspx
    <telerik:RadGrid ID="RadGrid1" runat="server" AllowPaging="True" AllowSorting="True" GridLines="None" AllowMultiRowSelection="True" AllowFilteringByColumn="True" EnableLinqExpressions="False">
        <MasterTableView AutoGenerateColumns="False">
            <PagerStyle AlwaysVisible="True"></PagerStyle>
            <Columns>
                <telerik:GridClientSelectColumn UniqueName="checkboxColumn1" HeaderTooltip="SELECT All" ShowSortIcon="False" ShowFilterIcon="False" Reorderable="False">
                    <HeaderStyle Width="30px" />
                <telerik:GridBoundColumn DataField="NumberOfBlocks" HeaderText="Block Count" UniqueName="NumberOfBlocks" AllowFiltering="False" Display="False">
                    <HeaderStyle Width="20px" />
                </telerik:GridBoundColumn>
                <telerik:GridTemplateColumn DataField="Block" HeaderText="Blocks" UniqueName="BlocksColumn" AllowFiltering="False">
                    <ItemTemplate>
                        <asp:PlaceHolder ID="phBlocksCheckBox" runat="server" />
                    </ItemTemplate>
                </telerik:GridTemplateColumn>
            </Columns>
        </MasterTableView>
        <ClientSettings AllowColumnsReorder="True" AllowDragToGroup="True" ReorderColumnsOnClient="True">
            <Scrolling UseStaticHeaders="True" />
            <Selecting AllowRowSelect="True" />
            <ClientEvents OnRowSelected="RowSelected" OnRowDeselected="RowDeselected"></ClientEvents>
        </ClientSettings>
    </telerik:RadGrid>


vb
    Protected Sub Button_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles GenerateCassetteLabelsButton.Click
        Dim NumberOfBlocks As Integer = 0

        For Each item As GridDataItem In RadGrid1.SelectedItems
            NumberOfBlocks = CInt(item("NumberOfBlocks").Text)

            Dim phBlocksCheckBox As PlaceHolder = DirectCast(item.FindControl("phBlocksCheckBox"), PlaceHolder)
            If phBlocksCheckBox IsNot Nothing Then
HttpContext.Current.Response.Write("phBlocksCheckBox IsNot Nothing<br><br>")
                For cbIndex As Integer = 1 To NumberOfBlocks
HttpContext.Current.Response.Write("-BlockCheckBoxID : " & "BlockCheckBox_" & cbIndex & "<br><br>")
                    Dim BlockCheckBox As CheckBox = DirectCast(phBlocksCheckBox.FindControl("BlockCheckBox_" & cbIndex), CheckBox)

                    If BlockCheckBox IsNot Nothing Then
HttpContext.Current.Response.Write("BlockCheckBox IsNot Nothing<br><br>")
                        'Do something with BlockCheckBox.Text
HttpContext.Current.Response.Write("-Block : " & BlockCheckBox.Text & "<br><br>")
                    End If
                Next
            End If
        Next

        RadGrid1.Rebind()
    End Sub

    Protected Sub RadGrid1_ItemDataBound(sender As Object, e As GridItemEventArgs) Handles RadGrid1.ItemDataBound
        'Ensure we are dealing with a data item (not header, footer, etc.)
        If TypeOf e.Item Is GridDataItem Then
            Dim item As GridDataItem = DirectCast(e.Item, GridDataItem)

            'Find the placeholder control defined in the ItemTemplate
            Dim phBlocksCheckBox As PlaceHolder = CType(item.FindControl("phBlocksCheckBox"), PlaceHolder)

            If phBlocksCheckBox IsNot Nothing Then
                Dim NumberOfBlocks As Integer = DataBinder.Eval(item.DataItem, "NumberOfBlocks")

                'Dynamically create and add checkboxes
                If NumberOfBlocks > 0 Then
                    For BlockIndex As Integer = 0 To NumberOfBlocks - 1
                        Dim BlockCheckBox As New CheckBox()
                        BlockCheckBox.ID = "BlockCheckBox_" & (BlockIndex + 1).ToString()
                        BlockCheckBox.Text = (BlockIndex + 1).ToString()
                        BlockCheckBox.Checked = True
                        phBlocksCheckBox.Controls.Add(BlockCheckBox)
                        phBlocksCheckBox.Controls.Add(New LiteralControl("    "))
                    Next
                End If
            End If
        End If
    End Sub

 

Vasko
Telerik team
 answered on 02 Mar 2026
1 answer
17 views

I have a NET core app and calling an external API fropm another site which returns anJSON that looks like this

[
  {
    "powerDeviceName": "Datarack",
    "powerDeviceUnitName": "Datarack Fas 1",
    "color": "red",
    "dateInfo": "2026-01-01T00:00:00",
    "consumption": "44.35"
  },
  {
    "powerDeviceName": "Datarack",
    "powerDeviceUnitName": "Datarack Fas 1",
    "color": "red",
    "dateInfo": "2026-01-02T00:00:00",
    "consumption": "44.38"
  },
  {
    "powerDeviceName": "Datarack",
    "powerDeviceUnitName": "Datarack Fas 1",
    "color": "red",
    "dateInfo": "2026-01-03T00:00:00",
    "consumption": "44.38"
  },
   {
    "powerDeviceName": "Datarack",
    "powerDeviceUnitName": "Datarack Fas 2",
    "color": "blue",
    "dateInfo": "2026-01-01T00:00:00",
    "consumption": "291.59"
  },
  {
    "powerDeviceName": "Datarack",
    "powerDeviceUnitName": "Datarack Fas 2",
    "color": "blue",
    "dateInfo": "2026-01-02T00:00:00",
    "consumption": "293.00"
  },
  {
    "powerDeviceName": "Datarack",
    "powerDeviceUnitName": "Datarack Fas 2",
    "color": "blue",
    "dateInfo": "2026-01-03T00:00:00",
    "consumption": "289.21"
  },
 {
    "powerDeviceName": "Datarack",
    "powerDeviceUnitName": "Datarack Fas 3",
    "color": "yellow",
    "dateInfo": "2026-01-01T00:00:00",
    "consumption": "228.62"
  },
  {
    "powerDeviceName": "Datarack",
    "powerDeviceUnitName": "Datarack Fas 3",
    "color": "yellow",
    "dateInfo": "2026-01-02T00:00:00",
    "consumption": "577.15"
  },
  {
    "powerDeviceName": "Datarack",
    "powerDeviceUnitName": "Datarack Fas 3",
    "color": "yellow",
    "dateInfo": "2026-01-03T00:00:00",
    "consumption": "295.35"
  }
]

From this I want to create a chart with series that matches the "powerDeviceUnitName" values (with the color from JSON) and the axis will list all dates in dateInfo The "value" for the chart is "consumption"

I didn't thought this should be any hard issue, but I can't find any example on Teleriks demos that have external JSON?

 

Anyone that can help me in the right direction?

Regards Pelle

Eyup
Telerik team
 answered on 25 Feb 2026
2 answers
47 views

When adding a PDFViewer component, I get this error:

jQuery.Deferred exception: mI is not a function TypeError: mI is not a function

  at DV.loadDocument (http://localhost:56126/lib/kendo-ui/js/kendo.all.min.js:9:4666164)
    at DV.loadFile (http://localhost:56126/lib/kendo-ui/js/kendo.all.min.js:9:4666007)
    at new DV (http://localhost:56126/lib/kendo-ui/js/kendo.all.min.js:9:4660492)
    at init._loadPdfJSDocument (http://localhost:56126/lib/kendo-ui/js/kendo.all.min.js:9:4725966)
    at new init (http://localhost:56126/lib/kendo-ui/js/kendo.all.min.js:9:4710755)
    at HTMLDivElement.<anonymous> (http://localhost:56126/lib/kendo-ui/js/kendo.all.min.js:9:66968)
    at ce.each (http://localhost:56126/js/jquery-3.7.0.min.js:2:3129)
    at ce.fn.init.each (http://localhost:56126/js/jquery-3.7.0.min.js:2:1594)
    at e.fn.<computed> [as kendoPDFViewer] (http://localhost:56126/lib/kendo-ui/js/kendo.all.min.js:9:66944)
    at HTMLDocument.<anonymous> (http://localhost:56126/MyFolder/MyPage?ticketid=11:703:100) undefined

This occurs whether I use a valid PDF file on initial load, or if I use the menu to open and test an existing document.
Danielle
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Iron
Iron
Iron
 answered on 19 Feb 2026
1 answer
24 views

Unable to find package Telerik.UI.for.AspNet.Core with version (>= 2021.3.1109)
  - Found 1 version(s) in nuget.org [ Nearest version: 2016.3.914 ]
  - Found 0 version(s) in Microsoft Visual Studio Offline Packages

 

 

Duplicate 'Content' items were included. The .NET SDK includes 'Content' items from your project directory by default. You can either remove these items from your project file, or set the 'EnableDefaultContentItems' property to 'false' if you want to explicitly include them in your project file. For more information, see https://aka.ms/sdkimplicititems. The duplicate items were: 'nlog.config'

Anton Mironov
Telerik team
 answered on 12 Feb 2026
1 answer
30 views

Good afternoon,

Using the demo https://demos.telerik.com/aspnet-core/grid/custom-command edited in REPL I have added some extra columns and grouping, plus a custom command whose visibility is conditional.

When I make the grid scrollable and contained in a div whose class is "container" the custom command column is hidden at runtime.

Index.html:

<div class="container">
@(Html.Kendo().Grid<Kendo.Mvc.Examples.Models.EmployeeViewModel>()
    .Name("Grid")
    .Columns(columns => {
        columns.Command(command => command.Custom("Close").Click("showDetails").Visible("colVisible"));
        columns.Bound(e => e.Title);
        columns.Group(group => group
            .Title("Name")
            .Columns(name => {
                name.Bound(e => e.FirstName).Width(80);
                name.Bound(e => e.LastName).Width(80);
            })
        );
        columns.Bound(e => e.FirstName).Width(80);
        columns.Bound(e => e.LastName).Width(80);
        columns.Bound(e => e.Title).Width(250);
        columns.Bound(e => e.FirstName).Width(80);
        columns.Bound(e => e.LastName).Width(80);
        columns.Bound(e => e.Title).Width(250);

    })
    .Size(ComponentSize.Small)
    .Scrollable()
    .Sortable()
    .Resizable(resize => resize.Columns(true))
    .DataSource(dataSource => dataSource
        .Ajax()
        .Read(read => read.Action("CustomCommand_Read", "Grid"))
     )
)
</div>
@(Html.Kendo().Window().Name("Details")
    .Title("Customer Details")
    .Visible(false)
    .Modal(true)
    .Draggable(true)
    .Width(300)
)

 <script type="text/x-kendo-template" id="template">
    <div id="details-container">
        <h2>#= FirstName # #= LastName #</h2>
        <em>#= Title #</em>
        <dl>
            <dt>City: #= City #</dt>
            <dt>Address: #= Address #</dt>
        </dl>
    </div>
</script>

Script.js:

   function showDetails(e) {
        e.preventDefault();

        var detailsTemplate = kendo.template($("#template").html());
        var dataItem = this.dataItem($(e.currentTarget).closest("tr"));
        var wnd = $("#Details").data("kendoWindow");

        wnd.content(detailsTemplate(dataItem));
        wnd.center().open();
    }

    function colVisible(dataItem) {
        var visible = dataItem.LastName == "Fuller";
        return !visible;
    }

Is there a way to make the custom command appear?  I guess that the width of the grid is being set by "container", I've predefined column widths of some of the columns, and it works out which columns appear before the visibility of the custom command is decided, so that appears behind the first Title column?

Kind regards,

Richard

Anton Mironov
Telerik team
 answered on 29 Jan 2026
1 answer
31 views

I have a grid where I am using a custom grouping javascript event becuase one of the columns is using an editor template, when they group by that column, I want them to actually group by the hidden column containing the data for the column, not the ID.

When I drag the item to group it, the category name displays fine, having run through my javascript function.  

But when I click the three dots and use the column menu, and select Group, it uses the ID instead, and you can see that is what it is grouped by in the header. 

I suppose I could get around this by setting a custom group header for it?  I'm just not sure why it's by passing my javascript.

Eyup
Telerik team
 answered on 29 Jan 2026
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