Hello,

 iam found "strange" behaviour compared to previous versions in combobox, with custom paging, filtering, valuemapper.

"simple description":
- Do not call OnRead and ValueMapper AFTER clicking/selecting the ITEM in any case(after filtering, or after scrolling...). Do it same way as selecting WITHOUT prior filtering.

Complex test

A sample for testing is here(and comments inside):
https://blazorrepl.telerik.com/GGPwalvk09g228sm32

How to reproduce:

1 - start = value is PREselected - OK
2 - clear the combobox - OK
2 - input value 40  - slowly do not rush, number by number - OK
3- wait 2 seconds and Click/select item ("Name 401" etc) - NOK
observe the events fired(Exception/info: time - indicates that OnRead was fired again) 

Repeat the same WITHOUT filtering, just scrolling
observe the events fired = looks ok (Exception/info: time)

When selecting item by CLICKING on it(after filtering) looks like those events are fired:
- ValueMapper (why?)
- OnRead again(why again?)
- bind value (ok)
and sometimes ValueMapper again
it depends of "timing"

expected:
When selecting item by CLICKING on it:
- BIND the value. Everything is in there(no reason to call OnRead or ValueMapper)

Related, unexpected(video attachment):
Also when working in "real" scenario, AFTER clicking on item AFTER filtering, it returns full MODEL assembly path into to input filed, instead of clicked item
Lets have a list: {Name of the item,Another item,Next item}
entere in combobox/filter "name", results are shown ok, clicked on one and result shuld be ("Name of the item"), after clicking it returns "base model class name"
ie: "inwApp1.Pages.prozam.crm.EdcrmOrg+BaseKeyModel" - you dont want to see this :) .

There is different event orders for those 2 scenarios(it should be the same for both as at point 1) ):
1) when SELECTing item without filtering(just moving with scrollbar down to value 401 (only with onread and virtual paging)) = OK
2) when filtering by value "40" and SELECTing item by clicking on it - NOT OK = it look like this causes the problems and subsequent event calls

Is there any workaround, or new "property" to set? Thanks

We are needing a way to display a hierarchy inside the ComboBox.  I don't see any examples on this particular feature, I had found a similar request, but not identical.

Our use case:

We have administrators that manage multiple tenants within our system.  The tenants are part of a hierarchy, the user needs to be able to select a tenant or tenant parent.

I will use hotels as an example:

-Chain 1

--Brand 1

---Property 1

---Property 2

--Brand 2

---Property 3

Our current system that we are migrating controls from has this feature, so I would like to stick as close to this functionality as possible, however; if it is not an option, what control would you suggest as an alternative.

See example (sorry for the redactions)

The core concept is providing a user a choice as part of a form, but layout needs to be organized so that a user can easily navigate.  Top level names are unique, all other names can duplicate since they may share similar naming conventions across different organizations.

An option that may work as an alternative, is invoking a dialog popup and within it having a tree list of the information I need.  I think it could work, but it would certainly break the flow of the form.

Hi Telerik Support.

I am using TelerikComboBox with Virtualization and enabled Filtering.  If I filter for a text and then scroll down, the filter text gets cleared. I am using OnRead event to populate the combo box. But the same issue is seen with local data population in the below sample code.

https://demos.telerik.com/blazor-ui/combobox/virtualization

I need to show the user the text they have entered even when they scroll down to the next page. Is there a solution for this? 

Regards

Bably

If the AllowCustom parameter is set to true and the OnChange fires during the data load, the value in the OnChange handler is null. Press Enter before the data load ends and the OnChange handler will give null instead of the current input value.

If I enter a text and press enter when there are no items (yet), I expect it to call the OnChange with that text. Even with a static list of zero items (replace 'Read=' with 'Data=' en provide a new List<>()), the OnChange is passed a null value.

If the OnChange fires before the empty dropdown get opened, it passes a null value, if it fires after the empty dropdown opens, it passes the entered text. That doesn't sound logical to me. Why needs the (empty) dropdown to be open before the data gets passed? And if that is necessary, why gets the OnChange fired before the dropdown is opened, and doesn't wait till it is open and then fire with the entered data?

If my browser culture is set to Swedish, I can no longer tab through multiple ComboBoxes.

<AdminEdit>

You can manually add the TabIndex parameter to each ComboBox and set their values to non-negative integers.

</AdminEdit>

I have a ComboBox that allows me to select different entities that I want to edit data for.  Some of this data involves selecting other options from ComboBoxes.  When I type in my cascading filterable ComboBox to select an item, its value changes accordingly, but when I change the entity I'm editing, that ComboBox doesn't display the selected value, even though there is a selected value present.

Reproduction: https://blazorrepl.telerik.com/GGYgmlFA45guzWlg06.

Steps to reproduce:

1. Run the snippet - selected Person is Adam
2. Start typing "Green" in the Fav Colour ComboBox
3. Press Enter to select it
4. Change the Person to John
5. Fav Colour appears empty while it should display "Yellow"

I would like to use an event that fires only when the user clicks on an item from the dropdown. 

=====

ADMIT EDIT:

Here is a possible way to achieve this now:

<TelerikComboBox @bind-Value=@SelectedValue
                 Data="@ComboBoxData"
                 ValueField="ProductId"
                 TextField="ProductName">
    <ItemTemplate>
        @{
            var currentItem = context as Product;

            <div onclick="@(() => OnClickHandler(currentItem))" style="width:100%">
                @currentItem.ProductName
            </div>
        }
    </ItemTemplate>
</TelerikComboBox>

@code {
    private void OnClickHandler(Product item)
    {
        //the application logic here
    }

    public IEnumerable<Product> ComboBoxData { get; set; }
    public int SelectedValue { get; set; } = 2;

    protected override void OnInitialized()
    {
        List<Product> products = new List<Product>();
        for (int i = 1; i < 10; i++)
        {
            products.Add(new Product()
                {
                    ProductId = i,
                    ProductName = $"Product {i}",
                    UnitPrice = (decimal)(i * 3.14)
                });
        }

        ComboBoxData = products;
        base.OnInitialized();
    }

    public class Product
    {
        public int ProductId { get; set; }
        public string ProductName { get; set; }
        public decimal UnitPrice { get; set; }
    }
}

Description

When the user types a value in the input and wishes to navigate to the beginning or end (by pressing Home/End buttons) of the input to make a correction, a value from the popup is actually selected and the value in the input is overridden.

Reproduction

1. Create a ComboBox and enable filtering.

2. Start typing in the input. Popup is opened.

3 Try to navigate in the input via the Home/End buttons. A value from the popup is selected that overrides the value in the input. 

Hi Telerik Team,

One of the requirements for my team project is that the ComboBox needs to be sorted in descending order to list dates. We need to sort the groups and the options inside the groups.

Ideally, the ComboBox can have a SortDirection parameter that defines the order as SortAscending or SortDescending, and can display the ComboBox groups and options accordingly.

===

Admin Edit:

It would be useful if you could disable the default sorting of the groups as well.

A ComboBox is databound via OnRead. It has an initial value, but no data arrives after the first OnRead call. We call Rebind() to fetch data and then it populates, but the component value doesn't show.

Click the button. The ComboBox should show its initial value, but doesn't. A similar scenario worked until version 2.30, when there was no Rebind(), but we set Data directly.

The workaround is to set raise a flag in OnRead and set the value in OnAfterRenderAsync.

@using Telerik.DataSource.Extensions

<TelerikButton OnClick="@BindCombo">Rebind Combo</TelerikButton>

<TelerikComboBox TItem="@ComboItem"
                 TValue="int"
                 @ref="@ComboRef"
                 TextField="Text"
                 ValueField="Id"
                 OnRead="OnComboRead"
                 Width="200px"
                 @bind-Value="@ComboValue">
</TelerikComboBox>

@code {
    string FilterValue { get; set; } = "A";
    int ComboValue { get; set; } = 2;
    bool BindFlag { get; set; }
    bool ShouldResetValue { get; set; }
    IEnumerable<ComboItem> LegacyComboData { get; set; }

    TelerikComboBox<ComboItem, int> ComboRef { get; set; }

    void BindCombo()
    {
        BindFlag = true;
        ComboRef.Rebind();
    }

    protected override async Task OnAfterRenderAsync(bool firstRender)
    {
        if (ShouldResetValue)
        {
            // comment out the initially set value above to make the following line work
            ComboValue = 2;
            StateHasChanged();
        }

        await base.OnAfterRenderAsync(firstRender);
    }

    async Task OnComboRead(ComboBoxReadEventArgs args)
    {
        if (BindFlag)
        {
            var service = new MyService();

            var data = await service.GetComboItem(FilterValue);
            var result = await data.ToDataSourceResultAsync(args.Request);

            args.Data = result.Data;

            //ShouldResetValue = true;
        }
    }

    public class ComboItem
    {
        public int Id { get; set; }
        public string Code { get; set; }
        public string Text { get; set; }
    }

    public class MyService
    {
        public async Task<IEnumerable<ComboItem>> GetComboItem(string code)
        {
            await Task.Delay(300);

            var data = new[]
            {
                    new ComboItem{ Id = 1, Code = "A", Text = "ValueA1" },
                    new ComboItem{ Id = 2, Code = "A", Text = "ValueA2" },
                    new ComboItem{ Id = 3, Code = "A", Text = "ValueA3" },
                    new ComboItem{ Id = 4, Code = "B", Text = "ValueB4" },
                    new ComboItem{ Id = 5, Code = "B", Text = "ValueB5" },
                    new ComboItem{ Id = 6, Code = "B", Text = "ValueB6" },
                    new ComboItem{ Id = 7, Code = "C", Text = "ValueC7" },
                    new ComboItem{ Id = 8, Code = "C", Text = "ValueC8" },
                    new ComboItem{ Id = 9, Code = "C", Text = "ValueC9" },
                };

            return data.Where(x => x.Code == code).ToList();
        }
    }
}

The ComboBox will not display an initial selected item, if the value is equal to the type's default. Applies to integers, guids, etc.

This used to work until version 2.30.

Here is a REPL test page.

If the value type is nullable, a zero int value will work for initial item selection.

Hello, I would like to have a mutiselect dropdown like you have for ajax:

https://demos.telerik.com/aspnet-ajax/combobox/examples/functionality/checkboxes/defaultcs.aspx

Syncfusion and radzen have this support for blazor :

https://blazor.syncfusion.com/demos/multiselect-dropdown/checkbox?theme=bootstrap5

https://blazor.radzen.com/dropdown

I know that you have a proposed solution for the MultiSelect component:

CheckBox in Multiselect

But the design of this one is not what I'm after, the box still expands downwards when selecting multiple items and it makes it hard to design a coherent page that does not make the dom "jump around". Also the implementation is cumbersome for more complex objects .

It would be better with a solution like you have for ajax where it just shows the first items that fits and then "+X items".

See this REPL:

https://blazorrepl.telerik.com/QmOFQTbW46QegjwX11

Run the program and scroll so that new data will be requested.  The page variable does not change, so I'm not able to request new data from my datasource.

I have a ComboBox/DropDownList that gets data from a remote service, using virtualization. When the PageSize property is big enough (in my case 20), I have issues scrolling up the selection box dropdown list. I'm trying to scroll but then resets to the currently selected item making it almost impossible to scroll up. You can use your own demo examples to replicate this issue.

To reproduce the issue, try the ComboBox - Virtualization, in Telerik REPL (Demo), change the PageSize from 10 to 20. Open the dropdown and select an item. Then, open again the dropdown and scroll slowly up.

Thanks for adding more new controls to Blazor. That help us to move to it from ASPX AJAX.

Can we have the Multi-Column ComboBox, like the ASPX AJAX that one, please?

https://www.telerik.com/products/aspnet-ajax/ajax-multicolumncombobox.aspx

Example Repo: https://github.com/benhysell/BlazorGridPagingIssue

Steps To Reproduce

• Run application and navigate to https://localhost:5001/updateweather
• Examine the ComboBoxes 'OData Weather Forecasts' and 'OData User' appears correct
• Stop application, change package reference for Telerik.UI.for.Blazor from version 2.25.0 to version 2.26.0
• Clean/Rebuild/run application and navigate back to https://localhost:5001/updateweather
• ComboBox now appears 'doubled', there are two boarders around the ComboBox

GitHub Repo - https://github.com/benhysell/BlazorGridPagingIssue

Expected Behavior - In the ComboBox ItemTemplate show the user's email address along with user name

Actual Behavior - Works fine debugging in Visual Studio, however in a published application the browser throws exception and will not display user's email address in the ItemTemplate.

Steps To Reproduce

• Clone and start debugging application
• Navigate to https://localhost:5001/createWeather
• This is a simple form with two ComboBoxes, one for weather data and one for user data
• In debug the ComboBoxes work as expected, each has an ItemTemplate that shows the desired data.
• Stop debugging and publish the applicaiton
• ie -- dotnet publish -o "YOUR DESIRED OUPUT DIRECTORY" -r win-x64 --self-contained
• Navigate to the output directory and run .\BlazorGrid.Server.exe
• In the browser navigate to https://localhost:5001/createWeather
• The page now throws an exception
• Also notice how the user's email address is no longer shown for the User in the comobobox drop down.

Details

Ran across this in a larger application...I have a class that inherits from Microsoft.AspNetCore.Identity.IdentityUser<Guid> and wanted to display all of my users in a ComboBox with a custom ItemTemplate consisting of the Name and Email.  This works great in debug, however every time I publish/deploy the Email address is not shown.  The example repo is a stripped down version of the larger application reproducing the error.

The application is making an OData call to the backend to retrieve the Users...in the repo we do not goto a database, in the live application we do.  In both instances the user's Email is not shown in the ItemTemplate, even though one can see via the browser's network traffic tab the results from the OData call include the email address for the users.

This issue does not just affect the email property, I was unable to get any of the properties listed on Microsoft.AspNetCore.Identity.IdentityUser<Guid> to render in a published application in the ItemTemplate for the Combobox. 

Note - all of the properties in Microsoft.AspNetCore.Identity.IdentityUser<Guid> are marked as 'virtual'.  I attempted to re-create this issue with a different class, in the repo I used the WeatherForecast class and created a virtual TemperatureK property...this however worked in debug and release without issue.  One can see this in the OData Weather Forecasts ComboBox on the same page, https://localhost:5001/createWeather.

I am working on a form where experienced agents need to input data quickly. Often enough they know the codes and so they can type them in the combo box, but they shouldn't have to look for the mouse to select the item, the combo box should select it when the user presses Tab to move to the next field.

This should happen only when the user has filtered the combo box so they see some items (and so the dropdown is open) - I want them to be able to select only items from the available options, AllowCustom does not work for me.

---

ADMIN EDIT

Here is one workaround you can consider:

https://blazorrepl.telerik.com/QoOAPyEZ233YP2AX19

@inject IJSRuntime js

@* Move this script to a separate JS file *@
<script suppress-error="BL9992">
    function getHighligtedComboItem() {
        // Get the currently focused item in this particular ComboBox.
        var focusedItem = document.querySelector(".select-on-tab .k-list-item.k-focus");
        if (focusedItem) {
            return focusedItem.innerText;
        }
    }
</script>

<p>FirstFilteredItem: @FirstFilteredItem</p>

<p>Selected value: @ComboBoxValue</p>

<span onkeyup="@GetFirstFilteredItem">
    <TelerikComboBox Data="@ComboBoxData"
                     Value="@ComboBoxValue"
                     ValueChanged="@( (int newValue) => ComboBoxValueChanged(newValue) )"
                     TextField="@nameof(ListItem.Text)"
                     ValueField="@nameof(ListItem.Value)"
                     Filterable="true"
                     FilterOperator="@StringFilterOperator.Contains"
                     OnBlur="@SelectItemOnTab"
                     OnOpen="@( () => IsComboBoxOpen = true )"
                     OnClose="@( () => IsComboBoxOpen = false )"
                     Placeholder="Select an item..."
                     ClearButton="true"
                     Width="200px">
        <ComboBoxSettings>
            <ComboBoxPopupSettings Class="select-on-tab" />
        </ComboBoxSettings>
    </TelerikComboBox>
</span>

<input placeholder="another form element" />

@code {
    private IEnumerable<ListItem> ComboBoxData = Enumerable.Range(1, 123).Select(x => new ListItem { Text = "Item " + x, Value = x });

    private int ComboBoxValue { get; set; }

    private string FirstFilteredItem { get; set; } = string.Empty;

    private bool IsComboBoxOpen { get; set; }

    private async Task GetFirstFilteredItem(KeyboardEventArgs args)
    {
        if (!IsComboBoxOpen)
        {
            // Wait at least 300ms, which is the opening animation.
            await Task.Delay(400);
        }
        else
        {
            // Wait, depending on the typical filtering time.
            await Task.Delay(300);
        }

        // The code that will find the item text depends on the exact scenario and potential use of ItemTemplate.
        FirstFilteredItem = await js.InvokeAsync<string>("getHighligtedComboItem");
    }

    private void SelectItemOnTab()
    {
        if (!string.IsNullOrEmpty(FirstFilteredItem))
        {
            // Match the filter operation to the filter operator of the ComboBox.
            var matchingItem = ComboBoxData.Where(x => x.Text.ToLowerInvariant().Contains(FirstFilteredItem.Trim().ToLowerInvariant())).FirstOrDefault();
            if (matchingItem != null)
            {
                ComboBoxValue = matchingItem.Value;
                FirstFilteredItem = string.Empty;
            }
        }
    }

    private void ComboBoxValueChanged(int newValue)
    {
        ComboBoxValue = newValue;
        FirstFilteredItem = string.Empty;
    }

    public class ListItem
    {
        public int Value { get; set; }
        public string Text { get; set; } = string.Empty;
    }
}