The null type of operator can cause errors on the backend

*** Thread created by admin on customer behalf ***

Hi,

I have found a bug with the TelerikNumericTextBox in that it doesn't function correctly with nullable types (at least it doesn't with Nullable<int>). I have confirmed this is the case for both 2.28 and 2.29 versions of Kendo for Blazor.

Description of the issue:

If "TelerikNumericTextBox" is "@bind-Value" to a nullable int, the control exhibits some unusual behaviour. If you manually type 0 into the control, it is accepted and the value updates the view-model property. However, if you use either the down-arrow button or arrow keys to select 0 (on a fresh load so there is no existing value selected/set), it does not set/update the view-model property. However, it does work correctly if you select another value first (such as 1) and then select 0.

Unfortunately, this is confusing the end-users of my application and I believe it is a bug (I haven't noticed this when using the Kendo for Angular or Kendo for JQuery).

In my application, I need users to be able to set the value of 0 but we do not want to set an initial value for the NumericTextBox to be 0 as this could lead our customers on; the application in question is requiring the end-user to manually select the number rather than allowing them to just leave it as default. Therefore, the view-model property I am binding to has been put as "int?" so that the default value is null and validation will require the user to select a valid value if they just try and press save without making any changes. Please note, for our use case, the number 0 is a valid option!

Steps to reproduce the issue:

Use the following razor HTML

The new value is: @TheValue

<TelerikNumericTextBox Format="D" Max="10" Min="0" Step="1" @bind-Value="@TheValue"></TelerikNumericTextBox>

@code {
    public int? TheValue { get; set; }
}

Click into the control and either press "down" on the keyboard arrow keys or press the "down" icon next to the control, so the value is set to be 0. The number 0 will not be set/persisted to the view-model property even though the control shows a 0 value.

If you have multiple controls on the page, following the above steps will mean that as soon as you click into another control, 0 is deleted (I believe because the VM prop has not been set), this does not happen if you type 0 into the control.

HOWEVER

If you continue to use the same Razor code above and any of the following workflows, it will set the controls view-model property correctly:

• Type 0 into the control - value is set correctly and property on the view-model is updated
• Select "up" on the keyboard (so the value is 1) and then press down (so the value is 0) - 0 is set correctly and property on the view-model is updated
• Select "up" on the numeric textbox's up arrow button (so the value 1) and then press "down" on the down arrow button (so the new value is 0) - 0 is set correctly and property on the view-model is updated

Additional notes:

• I have noticed this only seems to apply to the nullable version of the int type, if the prop is just an int, the control works fine but is automatically defaulted to 0 (which is not appropriate for my use case)
• It seems that as soon as the control/view model property has an initial value, the control behaves normally and the issue no longer happens anymore (both with keyboard navigation and the control's up/down buttons).
• I have not tested with any other types/primitives, just on INT so far
• I have confirmed this happens if you have the control in an "<EditForm/>" or outside of an EditForm. 

I have attached a sample project where I have replicated the issue, it is just a simple NET5 WASM Blazor project (generated from the default template) and I have just added the latest Kendo for Blazor. Nothing else has been done except for demoing on the "index.razor" both binding approaches I have tried/been able to replicate this issue on.

I hope the above makes sense, let me know if you need any further clarification.

Hi Telerik team,

When I want to bind the Blazor Grid to an ExpandoObject I need to assign the FieldType. I know I have to use non-nullable types.

But I want to use nullable types (for example int?) to have a blank cell within the Grid when there is no value for it. With "typeof(int)" instead of "typeof(int?)" every empty cell shows "0" which I don't want.

Is there any chance to let FieldType accept nullable types?

Best regards,

Rayko

The event would fire when the map zoom level has changed.

===

ADMIN EDIT: The new zoom level should be accessible in the event handler.

When I assign an Id to a FormGroup in TelerikForm, it's value can be seen in code, but neither the attribute nor it's value get rendered.

When the MultiColumnComboBox columns are rendered with a foreach loop, the component doesn't remove columns that are no longer defined.

The workaround is to recreate the MultiColumnComboBox: https://blazorrepl.telerik.com/wSOIvzvR46lEZrwy43

It would be nice to have an ability to group CustomTool / icons much like we can do EditorButtonGroup(s) - e.g.

new CustomToolGroup (new CustomTool("Save"),  new CustomTool("Import"), new CustomTool("Export"))

There is a change in the Grid behavior from version 4.6.0 to 5.0.0.

Consider the following REPL test page: https://blazorrepl.telerik.com/cSabmRPy306iPiXK18

Clicking on a Grid cell for editing will not open it for editing if there is already an open cell in edit mode on the same table row. The issue is reproduced more easily if the OnUpdate handler is empty or not defined at all.

This used to work in version 4.6.0.

You can move a modal window past the bottom and out of view. At that point the only way to get back to it is to zoom out on the browser. Similarly, if you drag a window to the top, you can move it so high that the title bar is out of view. You can still see the bottom part of the window but even if you zoom out you can't get back to the title bar so the only thing you can do is to either escape out of the window or hope you have Ok/Cancel still visible.

---

ADMIN EDIT

Until a feature is implemented that can do this automatically (whether behind a flag like in our WebForms suite or not), you can handle the window events to check the Top and Left values and compare them with the viewport and the window size.

Here is a basic example:

<TelerikWindow Left="@TheLeft" Top="@TheTop" Draggable="true"
               LeftChanged="@LeftChangedHandler" TopChanged="@TopChangedHandler"
               Visible="true" Width="400px" Height="300px">
    <WindowTitle>Drag me!</WindowTitle>
    <WindowContent>When using Left and Top, make sure to update them in the view-model.</WindowContent>
    <WindowActions>
        <WindowAction Name="Minimize"></WindowAction>
        <WindowAction Name="Maximize"></WindowAction>
    </WindowActions>
</TelerikWindow>

@code{
    string TheLeft { get; set; } = "50px";
    string TheTop { get; set; } = "50px";

    async Task LeftChangedHandler(string currLeft)
    {
        float leftValue = float.Parse(currLeft.Replace("px", ""));
        Console.WriteLine("left " + leftValue);
        //left boundary
        if (leftValue < 0)
        {
            currLeft = "0px";
        }
        //right boundary - replace hardcoded values with current values from the viewport size
        //and take into account the dimensions of your window. This sample hardcodes values for brevity and clarity
        //you may find useful packages like this to get the viewport size https://www.nuget.org/packages/BlazorPro.BlazorSize/
        if (leftValue > 1000)
        {
            currLeft = "1000px";
        }


        TheLeft = currLeft;

        await DelayedRender();
    }

    async Task TopChangedHandler(string currTop)
    {
        float topValue = float.Parse(currTop.Replace("px", ""));
        Console.WriteLine("top: " + topValue);

        //top boundary
        if (topValue < 0)
        {
            currTop = "0px";
        }
        //bottom boundary - replace hardcoded values with current values from the viewport size
        //and take into account the dimensions of your window
        if (topValue > 600)
        {
            currTop = "600px";
        }

        TheTop = currTop;

        await DelayedRender();
    }

    async Task DelayedRender()
    {
        await Task.Run(async () =>
        {
            await Task.Delay(30);
            await InvokeAsync(StateHasChanged);
        });
    }
}

---

Hey Telerik team,

We encountered issue with DateTime picker which I was able to reproduce in your Documentation preview.

If you hover over the date time dropdown, but really slowly it bugs out and the view becomes unusable like this:

As you can see, the dropdown is messed up and it seems like the hover over the border is trying to trigger some action to change from date to time pick automatically

Jakub

When I updated to the latest version I noticed that the FormItems in AuthorizedViews were moved to the bottom of the form, Quick example:

<TelerikForm>
    <FormItems>
        <AuthorizeView>
            <Authorized>
                <FormItem Field="First"/>
            </Authorized>
        </AuthorizeView>
        <FormItem Field="Second"/>
    </FormItems>
</TelerikForm>

will end up like

<TelerikForm>
    <FormItems>
        <FormItem Field="Second"/>
        <FormItem Field="First"/>
    </FormItems>
</TelerikForm>

Hi,

I haven't been able to find this as a request or as a topic of discussion (If it iss feel free to point me to it and close this request) but I feel the Grouping feature is limiting. If I use the group field in say the DropDownList the grouping works fine but it orders it alphabetically.

I propose adding a number of features to enhance this. The first being a GroupAscending or GroupDescending tag. Takes a boolean value and allows you to change the order to ascending (default/True) or descending (False).

The second, and more complicated feature upgrade could be a GroupOrder tag. This would take a List of the group field names ordered in the way you require and apply that order to the grouping in the DropDownList. for instance if you had the list ordered as Category 1, Category 3, Category 2 it would display the items in each grouping in that order top to bottom.

Regards,

Luke