I am using .net core 3.5 and razor pages.   I have a file upload control that is calling OnPost even when the control explicitly says to call a different method name.

  @(Html.Kendo().Upload()
            .Name("files")
            .Multiple(false)
            .Async(a => a
                .Save("Async_Save", "New", new { Question = DebtorDropBox.Web.UI.Code.Question.DriversLicense })
                .AutoUpload(true)
            )
            .Events(e => e
                .Success("onSuccess")
                .Upload("onUpload")
                .Error("onError")
            )
            .Validation(validation => validation.AllowedExtensions(new string[] { ".jpg" }))
            .Validation(validation => validation.MaxFileSize(4000000))
        )

      for testing purposes I have added the following three methods to my page and no matter what It keeps calling OnPost.    Is there something I should be doing? 

        public async Task<ActionResult> Async_Save(IEnumerable<IFormFile> files, Question question)
        {
            return Page();
        }

        public async Task<ActionResult> OnPostAsync_Save(IEnumerable<IFormFile> files, Question question)
        {
            return Page();
        }

        public async Task<ActionResult> OnPost(IEnumerable<IFormFile> files, Question question)
        {
            return Page();
        }

How do I handle an exception that occurs when generating the data to be sent to the grid?  I've seen an example of a call to a Javascript "error_handler" method.  Is that my only option?

I have a grid very similar to the one in this telerik example where I am using 3 different client templates to populate and bind 3 drop downs in my grid:

https://demos.telerik.com/aspnet-core/grid/editing-custom

My dropdowns are: Category, Department, Configuration

So my grid is defined like this with custom editors

And the model I'm binding to looks just like in the example:

I need the dropdowns to cascade.....choose a Category, it loads Departments associated with that category, choose a Department, it loads configurations associated with that department. So my code in the custom editor is simply (this is for category, for department it passes the selected categoryId in the read action , etc)

And visually works correctly, choosing a category will re-fill the department options and by default the first item is now selected. But if you go to save it at this point, even though the first item is selected, the model does not reflect that: e.model.Department = null. You have to physically choose an item from the Department drop down to get it to set that model value correctly. What is going on here? Why is not binding the model to the selected item when it refills? 

Afternoon

Using Package Telerik.UI.for.AspNet.Core(2020.2.617)

Goal: 

I want to switch Kendo Menu to use k-i-menu rather than font awsome icon.

Problem

It is always blank when i reference the k-i-menu. This is because it adds k-sprite into the span it generates and that seems to cause the issues

e.g. <span class="k-sprite k-icon k-i-menu k-icon-32"></span>

Example Code

<span class="k-icon k-i-menu k-icon-32"></span> <-- this shows bars
<div style="padding-right: 5px" class="k-content">
    @(Html.Kendo().Menu().Name("NavMenu").Items(items =>
    {items.Add()
            .Items(innerChilderen =>
            {
                innerChilderen.Add().Text("Reports").Url("/Something");
            }).SpriteCssClasses("k-icon k-i-menu k-icon-32");  <--- this is blank
    }))
</div>

I assumed it would be an easy switch since it was already working with font awesome. Not sure if i'm missing something as far as using the kendo icons with this menu. Looking forward to your thoughts.

After upgrading from 2.2 to 3.1 my grid control no longer works.  I am available for a phone call if that is easier.

Note: I have success with Html.Kendo().Menu() but also failure on Html.Kendo().TreeList<Group>().  I verified I have valid data.

Project:

Shared._Layout:

I note that on this training your header looks different than mine.  Do I need to completely rework this?

https://docs.telerik.com/aspnet-core/getting-started/first-steps#adding-reference-to-kendomvcui

_ViewImports.cshtml

Grid:

Callback:

I'm migrating some code from netFramework asp.net to asp.net core and I found some unexpected behavior with an editor used everywhere in my old code.

I'm bounding a timestamp property in a table like this:

And I have an editor template for timestamps:

If I load the page containing the table y get an exception:

System.NullReferenceException: Object reference not set to an instance of an object.
   at Microsoft.AspNetCore.Mvc.ViewFeatures.ExpressionMetadataProvider.<>c__DisplayClass0_0`2.<FromLambdaExpression>g__modelAccessor|0(Object container)
   at Microsoft.AspNetCore.Mvc.ViewFeatures.ModelExplorer.get_Model()
   at Kendo.Mvc.UI.Fluent.WidgetFactory`1.NumericTextBoxFor[TValue](Expression`1 expression)
   at Kendo.Mvc.UI.Fluent.WidgetFactory`1.IntegerTextBoxFor(Expression`1 expression)
.....

The EditorTemplate works normally if I use in other pages like:

Thanks

    I creatred a new project using the Telerik template.  By default, the IAntiforgery token was injected.  In order to use that token, the Datasource invokes it this way:

    .DataSource(ds => ds.Ajax()
            .Read(r => r.Url("/Index?handler=Read").Data("forgeryToken"))

That .Data references to a script like this:

<script>
    function forgeryToken() {
        return kendo.antiForgeryTokens();
    }
</script>

Question... if I have additional data to include, how is the forgeryToken included?

I use a script like this:

Is it possible to do use a dynamic editor on a column with C# wrappers, like the example below does for jquery?  

https://docs.telerik.com/kendo-ui/knowledge-base/grid-use-dynamic-editor

How can I achieve similar functionality?  

I have a simple Preference object that can have different types of values.  (Boolean, String, Number, etc).  

The preference object has a DataType that tells it what type for each row.  I would like to use this value to determine what editortemplate to use.  

Thank you very much for your help.  

I based the implementation on the example video about TagHelpers. But no data is displayed. A call to the URL (https://localhost:44337/Suppliers/Read) provides data. What am I doing wrong?

SuppliersController:

Index.chtml:

_SuppliersGrid:

I'm using remote binding, but not appears arrow to expand node.

This is method

This is control

 I attached result