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.

The tablet that I am using is slightly wider than the medium breakpoints set in AdaptiveMode.Auto. However, I still want to show the action sheet. I'd like to be able to configure the breakpoints which are currently hard-coded.

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ADMIN EDIT

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The request is opened for ComboBox but it also targets other selects and pickers that have AdaptiveMode feature. For example, DropDownList, MultiSelect, DatePicker and more.

When the height of the popup is set to 'auto' and it opens upwards, the resizing process causes it to be incorrectly positioned.

# Reproduction:

1. Open this REPL - https://blazorrepl.telerik.com/mHuoPRFk52ienlUt52
2. Shrink the browser so that the ComboBox remains at the bottom of the window: 


3. Type "item 2" in the ComboBox

When selecting an item with the Enter key, the value is not displayed in the input field.

1. Open this REPL example
2. Open the ComboBox and navigate with the arrows to any item
3. Hit "Enter" to select the item

The item is selected, but its value is not displayed inside the input field.

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The issue is also reproducible with the MultiColumnComboBox component. 

Description

When selecting a value via the keyboard, the input element is out of sync.

Reproduction (if bug)

1. Create a Combobox and populate it with data.

2. Trigger a change with the keyboard.

3. The value is updated but the input holds the old value and is out of sync.

REPL for reproduction:

https://blazorrepl.telerik.com/GnEnPZun00tsuQEA47

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

When the user selects a value and then focuses on another component the OnBlur of the ComboBox is not triggered. The issue is reproducible in the Firefox browser (tested with version 109.0).

To reproduce the issue open the following REPL example in the Firefox browser:
https://blazorrepl.telerik.com/mdklmHYN06lVQjyL26

Select a value in the first ComboBox and then focus on the second ComboBox. The OnBlur event should trigger.

Hi,

EDIT: This issue (of course) relates to the case where the combobox has data selected when rendering.

The clear button of the combobox behaves in a way that I find strange, and which prevents us to get the desired behaviour in our application.

It is easily reproducable with your demo here:

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

When loading the page there is no clear button, which I think is wrong. Especially since it is not even in the DOM, so it cannot be made visible with styling. When clicking in the field, the clear button appears, and it stays there when changing focus to elsewhere, which seems inconsistent.

In other words, the span of the button (in the red box below) only appears when the combobox has had focus.

Thanks,

Niels

I would like the ability to flag elements in a data bound combo that are no longer available as disabled and not selectable.  Had they been previously selected, they still need to show, but should not allow a user to select it again.

I would like a property that can be set when databinding a combo.

For instance when you set the Data, TextField, & ValueField properties, can there also be one for SelectableField (or something) - this could be mapped to a Boolean in the dataset.

If this property isn't used then it defaults to yes (ie they are all selectable), but if it is used, then any items which have this field set to 'no' then they show as a different color (could just be grey) but are not selectable by the user.

If they had previously been selected (prior to being marked as no longer available) then they should show when the record is loaded, but otherwise they are not selectable.

I don't particularly want to write code on click to see if its enabled and then unselect it, I would prefer it to simply be built into the base control.

Is this possible?  Or is there another property already there that does this?

I would like to change the text in the ComboBox dropdown when there is no data in the source collection.

At the moment the only option is through localization for all instances like here.

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.

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>

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?

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

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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; }
    }
}

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"

In my data, I have multiple identical values for the TextField of the ComboBox. When the user selects one of them and focuses away from the component the selected value changes to the first instance of the items with the same TextFields, although they have different ValueFields.

Reproduction:

<TelerikComboBox Data="@myDdlData" 
                 TextField="MyTextField" 
                 ValueField="MyValueField" 
                 Value="selectedValue" 
                 ValueChanged="@((int? id) => ValueChangedHandler(id))" 
                 FilterOperator="StringFilterOperator.Contains"
                 Filterable="true">
</TelerikComboBox>

@code {
    private List<MyDdlModel> myDdlData { get; set; }

    private void ValueChangedHandler(int? id)
    {
        selectedValue = id;
    }

    public class MyDdlModel
    {
        public int? MyValueField { get; set; }
        public string MyTextField { get; set; }
    }

    int? selectedValue { get; set; }

    protected override void OnInitialized()
    {
        myDdlData = new List<MyDdlModel>()
        {
            new MyDdlModel()
            {
                MyValueField = 1,
                MyTextField = "John Smith"
            },
            new MyDdlModel()
            {
                MyValueField = 2,
                MyTextField = "John Smith"
            },
            new MyDdlModel()
            {
                MyValueField = 3,
                MyTextField = "John Smith"
            },
            new MyDdlModel()
            {
                MyValueField = 4,
                MyTextField = "Alice Jones"
            },
            new MyDdlModel()
            {
                MyValueField = 5,
                MyTextField = "Alice Jones"
            },
        };
    }
}

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.