Transitioning our application from Telerik React to Blazor, our comboboxes in our React application are hooked up to OData endpoints because of the amount of data they could display, some as large as 30mb of json.

Server filtering, https://feedback.telerik.com/blazor/1447481-server-filtering-with-custom-data-request-event-that-can-accommodate-remote-data, almost works, however:

• I can't set PageSize on the combobox
• I can't set TotalCount on the combobox
• Using Telerik.Blazor.ExtensionMethods.ToOdataString throws a NullReferenceException when I try to use it in the ReadItems method with the ComboBoxReadEventArgs args.Reqeuest.ToOdataString()

I tried setting up my combobox like my OData Grid, i.e.

<TelerikComboBox Data="@Dtos"
                         OnRead="@ReadItems"
                         Filterable="true"
                         Placeholder="Find what you seek by typing"
                         @bind-Value="@SelectedValue"
                         TextField="Name" 
                         ValueField="Id"
                         Pageable="true" 
                         PageSize="20" 
                         TotalCount=@Dtos.Count
                         >

However it throws an exception:

blazor.webassembly.js:1 WASM: System.InvalidOperationException: Object of type 'Telerik.Blazor.Components.TelerikComboBox`2[[MyType, MyNamespace, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[System.Guid, mscorlib, Version=2.0.5.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]]' does not have a property matching the name 'Pageable'.

Was hoping this would 'just work' like it does with the Grid, which is amazing!

Replication code:

@SelectedValue
<br />
<TelerikComboBox Data="@DdoData"
                 OnRead="@OnReadHandler"
                 Filterable="true"
                 ValueField="RecId"
                 TextField="DdoTitle"
                 Placeholder="Find what you seek by typing"
                 @bind-Value="@SelectedValue">
</TelerikComboBox>

@code{
    public int SelectedValue { get; set; } = 4;
    List<ddo> DdoData { get; set; }
    public string ddoCbType { get; set; } = "Default";
    int InitialId { get; set; }
    string currentText { get; set; } = "";

    protected override async Task OnInitializedAsync()
    {
        await ReadDdoData(ddoCbType, "");
        if (SelectedValue > 0)
        {
            InitialId = (int)SelectedValue;
            await ReadDdoData(ddoCbType, currentText);
        }
    }

    async Task OnReadHandler(ComboBoxReadEventArgs args)
    {
        if (args.Request.Filters.Count > 0)
        {
            Telerik.DataSource.FilterDescriptor filter = args.Request.Filters[0] as Telerik.DataSource.FilterDescriptor;
            currentText = filter.Value.ToString();
            await ReadDdoData(ddoCbType, currentText);
        }
        else
        {
            currentText = "";
            await ReadDdoData(ddoCbType, "");
        }
    }

    private async Task ReadDdoData(string ddoCbType, string currentText)
    {
        await Task.Delay(100);

        DdoData = new List<ddo>()
        {
                new ddo(){ RecId = 1, DdoTitle = "one"},
                new ddo(){ RecId = 2, DdoTitle = "two"},
                new ddo(){ RecId = 3, DdoTitle = "Three"},
                new ddo(){ RecId = 4, DdoTitle = "Four"},
                new ddo(){ RecId = 5, DdoTitle = "Five"}
            };

        //this does not help
        await InvokeAsync(StateHasChanged);
    }

    public class ddo
    {
        public int RecId { get; set; }
        public string DdoTitle { get; set; }
    }
}

When I select an item from the combo box dropdown, the OnChange event fires with the new value, but the model field is not updated yet.

@selectedValue

<TelerikComboBox Data="@myDdlData" TextField="MyTextField" ValueField="MyValueField"
                 @bind-Value="@selectedValue"  OnChange="@MyOnChangeHandler">
</TelerikComboBox>

@code {
    int selectedValue { get; set; }

    IEnumerable<MyDdlModel> myDdlData = Enumerable.Range(1, 20).Select(x => new MyDdlModel { MyTextField = "item " + x, MyValueField = x });
    
    private void MyOnChangeHandler(object theUserInput)
    {
        Console.WriteLine($"COMBO: the models is now {selectedValue} and the handler received {theUserInput}");
    }

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

ComboBox value binding broken in 2.9.0, works fine in 2.8.0

Please see your own documentation example:

<TelerikComboBox Data="@MyList" @bind-Value="MyItem">
</TelerikComboBox>

@code {
    protected List<string> MyList = new List<string>() { "first", "second", "third" };
    protected string MyItem { get; set; } = "second";
}

When i search for something by typing in combobox, i want to be able to use the keyboard to make my selection

Exable below, if i press b, I want to be able to either select baseboll by pressing enter, or make another selection by using arrow keys and then enter. 

Hi,

If I enter some characters in the ComboBox to filter it, the characters that I enter aren't shown and the filtering is not correct. Indeed, if I enter "ALU" (some of my data start with "ALU", no data appears.

I want to capture the user selection (which has to happen through ValueChanged, as OnChange does not fire when I need it). At this point I want to use the selection from the user and to clear the combo box.

I would expect that this should work but it does not:

@result
<br />
from model: @MyItem
<br />
<br />
<TelerikComboBox Data="@MyList" Value="@MyItem" ValueChanged="@( (string v) => MyValueChangeHandler(v) )" Placeholder="Choose something">
</TelerikComboBox>

@code {
    string result;
    private async Task MyValueChangeHandler(string theUserChoice)
    {
        result = string.Format("The user chose: {0}", theUserChoice);

        MyItem = null; // this should be enough

    }
    protected List<string> MyList = new List<string>() { "first", "second", "third" };
    protected string MyItem { get; set; } = "second";
}