DropDownList TValue int error (Blazor 17.4.39)

[ashimaz]

After upgrading to blazor 17.4.39 DropDownList TValue int is giving following error.

DropDownList value is:@DropVal

EjsDropDownList Placeholder="e.g. Australia" TItem="Countries" TValue="int" Value="@DropVal" DataSource="@Country"

    DropDownListEvents TValue="int" ValueChange="onChange"

    DropDownListFieldSettings Value="Code"

/EjsDropDownList

@code {

    public int DropVal = 0;

    public class Countries

    {

        public string Name { get; set; }

        public int Code { get; set; }

    }

    List Country = new List

{

        new Countries() { Name = "Australia", Code = 1 },

        new Countries() { Name = "Bermuda", Code = 2 },

        new Countries() { Name = "Canada", Code = 3 },

        new Countries() { Name = "Cameroon", Code = 4 },

    };

    private void onChange(Syncfusion.EJ2.Blazor.DropDowns.ChangeEventArgs args)

    {

        DropVal = args.Value;

        StateHasChanged();

    }

}

blazor.server.js:15 [2019-12-21T06:09:13.615Z] Error: System.InvalidCastException: Null object cannot be converted to a value type.

   at System.Convert.ChangeType(Object value, Type conversionType, IFormatProvider provider)

   at System.Convert.ChangeType(Object value, Type conversionType)

   at Syncfusion.EJ2.Blazor.BaseComponent.ChangeType(Object value, Type conversionType, Boolean isClientChange)

   at Syncfusion.EJ2.Blazor.DropDowns.EjsDropDownList`2.getItemData()

   at Syncfusion.EJ2.Blazor.DropDowns.EjsDropDownList`2.setValue()

   at Syncfusion.EJ2.Blazor.DropDowns.EjsDropDownList`2.updateValues()

   at Syncfusion.EJ2.Blazor.DropDowns.EjsDropDownList`2.initValue()

   at Syncfusion.EJ2.Blazor.DropDowns.EjsDropDownList`2.OnAfterRenderAsync(Boolean firstRender)

   at Microsoft.AspNetCore.Components.RenderTree.Renderer.GetErrorHandledTask(Task taskToHandle)

[Saranya Dhayalan]

Hi Ashimaz, 

 

Thank you for contacting Syncfusion support 

 

 

We have checked your reported issue, you need to specify int nullable type to DropDownList TValue. Please find the below code snippet: 

 

@using Syncfusion.EJ2.Blazor.DropDowns 

 

 

DropDownList value is:@DropVal 

 

 

<EjsDropDownList Placeholder="e.g. Australia" TItem="Countries" TValue="int?" Value="@DropVal" DataSource="@Country"> 

    <DropDownListEvents TValue="int?" ValueChange="onChange"></DropDownListEvents> 

    <DropDownListFieldSettings Value="Code" Text="Name"></DropDownListFieldSettings> 

</EjsDropDownList> 

 

@code { 

 

    public int? DropVal = 0; 

 

    public class Countries 

    { 

        public string Name { get; set; } 

 

        public int Code { get; set; } 

    } 

 

    List<Countries> Country = new List<Countries> 

{ 

        new Countries() { Name = "Australia", Code = 1 }, 

        new Countries() { Name = "Bermuda", Code = 2 }, 

        new Countries() { Name = "Canada", Code = 3 }, 

        new Countries() { Name = "Cameroon", Code = 4 }, 

    }; 

    private void onChange(Syncfusion.EJ2.Blazor.DropDowns.ChangeEventArgs<int?> args) 

    { 

       DropVal = args.Value; 

        StateHasChanged(); 

    } 

} 

 

 

Could you please check the above code snippet and get back to us if you need further assistance on this? 

 

 

Regards, 

Saranya D