Completed
Last Updated: 12 Dec 2019 12:39 by ADMIN
Release 2.5.1
Emil
Created on: 11 Dec 2019 06:03
Category: DropDownList
Type: Bug Report
0
Binding the value to a nullable enum throws an exception

Hello,

Initial I want no item to be selected to let the user select a value. I thought it would be enough if my bindvalue would be of a nullable type. I'm getting an exception when trying. If this is not supported, how can I do it?

 

     <div class="form-group col-md-2">
        <label class="col-form-label" for="ddReleaseType">F√∂nstertyp</label>
        <TelerikDropDownList Data="@ReleaseTypeFilterOptions" @bind-Value="FilterState.ReleaseType" TextField="DisplayText" ValueField="ReleaseType" Class="max-width form-control" @ref="ddReleaseType"></TelerikDropDownList>
    </div>

     public enum ReleaseType : int
    {
        All = 0,
        Category = 1,
        Season = 2,
        Misc = 3
    }

    public class FilterState
    {
        public ReleaseType? ReleaseType { get; set; }
    }

 

        protected Telerik.Blazor.Components.TelerikDropDownList<ReleaseTypeFilterModel?, SessionState.ReleaseType?> ddReleaseType;
 

        protected class ReleaseTypeFilterModel
        {
            public SessionState.ReleaseType ReleaseType { get; set; }
            public string DisplayText { get { return ReleaseType.ToString(); } }
        }
 

 

 

 

An unhandled exception occurred while processing the request.

InvalidOperationException: Telerik.Blazor.Components.TelerikDropDownList`2[ReleaseCalendar.Pages.IndexBase+ReleaseTypeFilterModel,System.Nullable`1[ReleaseCalendar.SessionState.ReleaseType]] does not support the type 'System.Nullable`1[ReleaseCalendar.SessionState.ReleaseType]'.

Telerik.Blazor.Components.Common.TelerikSelectBase<TItem, TValue>.TryParseValueFromString(string value, out TValue result, out string validationErrorMessage)

 

    • Telerik.Blazor.Components.Common.TelerikSelectBase<TItem, TValue>.TryParseValueFromString(string value, out TValue result, out string validationErrorMessage)

    • Telerik.Blazor.Components.Common.TelerikSelectBase<TItem, TValue>.set_CurrentValueAsString(string value)

    • Telerik.Blazor.Components.TelerikDropDownListBase<TItem, TValue>.OnParametersSet()

    • Microsoft.AspNetCore.Components.ComponentBase.CallOnParametersSetAsync()

    • Microsoft.AspNetCore.Components.ComponentBase.RunInitAndSetParametersAsync()

    • Microsoft.AspNetCore.Components.Rendering.HtmlRenderer.HandleException(Exception exception)

    • Microsoft.AspNetCore.Components.RenderTree.Renderer.AddToPendingTasks(Task task)

    • Microsoft.AspNetCore.Components.Rendering.ComponentState.SetDirectParameters(ParameterView parameters)

    • Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.InitializeNewComponentFrame(ref DiffContext diffContext, int frameIndex)

    • Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.InitializeNewSubtree(ref DiffContext diffContext, int frameIndex)

    • Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.InsertNewFrame(ref DiffContext diffContext, int newFrameIndex)

    • Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.AppendDiffEntriesForRange(ref DiffContext diffContext, int oldStartIndex, int oldEndIndexExcl, int newStartIndex, int newEndIndexExcl)

    • Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder.ComputeDiff(Renderer renderer, RenderBatchBuilder batchBuilder, int componentId, ArrayRange<RenderTreeFrame> oldTree, ArrayRange<RenderTreeFrame> newTree)

    • Microsoft.AspNetCore.Components.Rendering.ComponentState.RenderIntoBatch(RenderBatchBuilder batchBuilder, RenderFragment renderFragment)

    • Microsoft.AspNetCore.Components.RenderTree.Renderer.RenderInExistingBatch(RenderQueueEntry renderQueueEntry)

    • Microsoft.AspNetCore.Components.RenderTree.Renderer.ProcessRenderQueue()

    • Microsoft.AspNetCore.Components.Rendering.HtmlRenderer.HandleException(Exception exception)

    • Microsoft.AspNetCore.Components.RenderTree.Renderer.ProcessRenderQueue()

    • Microsoft.AspNetCore.Components.RenderTree.Renderer.ProcessPendingRender()

    • Microsoft.AspNetCore.Components.RenderTree.Renderer.AddToRenderQueue(int componentId, RenderFragment renderFragment)

    • Microsoft.AspNetCore.Components.ComponentBase.StateHasChanged()

    • Microsoft.AspNetCore.Components.ComponentBase.CallOnParametersSetAsync()

    • Microsoft.AspNetCore.Components.ComponentBase.RunInitAndSetParametersAsync()

    • Microsoft.AspNetCore.Components.Rendering.HtmlRenderer.HandleException(Exception exception)

    • Microsoft.AspNetCore.Components.RenderTree.Renderer.AddToPendingTasks(Task task)

    • Microsoft.AspNetCore.Components.Rendering.ComponentState.SetDirectParameters(ParameterView parameters)

    • Microsoft.AspNetCore.Components.RenderTree.Renderer.RenderRootComponentAsync(int componentId, ParameterView initialParameters)

    • Microsoft.AspNetCore.Components.Rendering.HtmlRenderer.CreateInitialRenderAsync(Type componentType, ParameterView initialParameters)

    • Microsoft.AspNetCore.Components.Rendering.HtmlRenderer.RenderComponentAsync(Type componentType, ParameterView initialParameters)

    • Microsoft.AspNetCore.Components.Rendering.RendererSynchronizationContext+<>c__11<TResult>+<<InvokeAsync>b__11_0>d.MoveNext()

    • Microsoft.AspNetCore.Mvc.ViewFeatures.StaticComponentRenderer.PrerenderComponentAsync(ParameterView parameters, HttpContext httpContext, Type componentType)

    • Microsoft.AspNetCore.Mvc.ViewFeatures.ComponentRenderer.PrerenderedServerComponentAsync(HttpContext context, ServerComponentInvocationSequence invocationId, Type type, ParameterView parametersCollection)

    • Microsoft.AspNetCore.Mvc.ViewFeatures.ComponentRenderer.RenderComponentAsync(ViewContext viewContext, Type componentType, RenderMode renderMode, object parameters)

    • Microsoft.AspNetCore.Mvc.TagHelpers.ComponentTagHelper.ProcessAsync(TagHelperContext context, TagHelperOutput output)

    • Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperRunner.<RunAsync>g__Awaited|0_0(Task task, TagHelperExecutionContext executionContext, int i, int count)

    • ReleaseCalendar.Pages.Pages__Host.<ExecuteAsync>b__14_1() in _Host.cshtml

      1.     <app><component type="typeof(App)" render-mode="ServerPrerendered" /></app>
    • Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperExecutionContext.SetOutputContentAsync()

    • ReleaseCalendar.Pages.Pages__Host.ExecuteAsync()

    • Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderPageCoreAsync(IRazorPage page, ViewContext context)

    • Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderPageAsync(IRazorPage page, ViewContext context, bool invokeViewStarts)

    • Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderAsync(ViewContext context)

    • Microsoft.AspNetCore.Mvc.ViewFeatures.ViewExecutor.ExecuteAsync(ViewContext viewContext, string contentType, Nullable<int> statusCode)

    • Microsoft.AspNetCore.Mvc.ViewFeatures.ViewExecutor.ExecuteAsync(ViewContext viewContext, string contentType, Nullable<int> statusCode)

    • Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResultFilterAsync>g__Awaited|29_0<TFilter, TFilterAsync>(ResourceInvoker invoker, Task lastTask, State next, Scope scope, object state, bool isCompleted)

    • Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResultExecutedContextSealed context)

    • Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.ResultNext<TFilter, TFilterAsync>(ref State next, ref Scope scope, ref object state, ref bool isCompleted)

    • Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeResultFilters()

    • Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResourceFilter>g__Awaited|24_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, object state, bool isCompleted)

    • Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResourceExecutedContextSealed context)

    • Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Next(ref State next, ref Scope scope, ref object state, ref bool isCompleted)

    • Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeFilterPipelineAsync()

    • Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Logged|17_1(ResourceInvoker invoker)

    • Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)

    • Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)


1 comment
ADMIN
Marin Bratanov
Posted on: 11 Dec 2019 15:05

Hi Emil,

I have logged this for fixing and you can Follow its status in the following page (I moved the ticket there for visibility): https://feedback.telerik.com/blazor/1445705-binding-the-value-to-a-nullable-enum-throws-an-exception.

I am attaching here two examples that showcase how this should work after it gets fixed (disclaimer - if the investigation points to something more complex, this may have to change). There are a few differences from the original samples that were provided, mostly in the way the value is bound (it needs to be a reference field, in this snippet it isn't, unless there is more pertinent code I'm missing).

On a side note - you don't really need the component reference, the label won't attach to it. The reference is just a memory pointer, it does not render as an id attribute. For the time being, you can wrap the entire component in the <label> tag.

 

Regards,
Marin Bratanov
Progress Telerik

 UI for Blazor
Attached Files: