Question

我想要一个TimeSpan编辑器，该编辑器具有分别用于天，小时，分钟和秒的字段。我有一个自定义编辑器tempalte，一个模型绑定器，一个模型绑定器提供程序，并注册了后者。

在呈现页面时发生NullReferenceException。

System.NullReferenceException：对象引用未设置为对象的实例。在Microsoft.AspNetCore.Mvc.ViewFeatures.Internal.ExpressionMetadataProvider处。<> c__DisplayClass0_0 {2.<FromLambdaExpression>g__modelAccessor|0(Object container) at Microsoft.AspNetCore.Mvc.ViewFeatures.ModelExplorer.get_Model() at Kendo.Mvc.UI.Fluent.WidgetFactory 1.NumericTextBoxFor [TValue]（Expression 1 expression) at Kendo.Mvc.UI.Fluent.WidgetFactory 1.IntegerTextBoxFor（Expression 1 expression) at AspNetCore.Views_Shared_EditorTemplates_TimeSpanNumeric.ExecuteAsync() in E:\Source\MCT\MCT\Views\Shared\EditorTemplates\TimeSpanNumeric.cshtml:line 5 at Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderPageCoreAsync(IRazorPage page, ViewContext context) at Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderPageAsync(IRazorPage page, ViewContext context, Boolean invokeViewStarts) at Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderAsync(ViewContext context) at Microsoft.AspNetCore.Mvc.ViewFeatures.Internal.TemplateRenderer.Render() at Microsoft.AspNetCore.Mvc.ViewFeatures.Internal.TemplateBuilder.Build() at Microsoft.AspNetCore.Mvc.ViewFeatures.HtmlHelper.GenerateEditor(ModelExplorer modelExplorer, String htmlFieldName, String templateName, Object additionalViewData) at Microsoft.AspNetCore.Mvc.ViewFeatures.HtmlHelper.Editor(String expression, String templateName, String htmlFieldName, Object additionalViewData) at Microsoft.AspNetCore.Mvc.Rendering.HtmlHelperEditorExtensions.Editor(IHtmlHelper htmlHelper, String expression, String templateName, Object additionalViewData) at Kendo.Mvc.UI.GridBoundColumn 2.GetEditor（IHtmlHelper helper ，HtmlEncoder编码器）在Kendo.Mvc.UI.Grid 1.<>c__DisplayClass69_1.<InitializeEditors>b__2(IGridBoundColumn column) at Kendo.Mvc.Extensions.EnumerableExtensions.Each[T](IEnumerable 1实例处，操作1 action) at Kendo.Mvc.UI.Grid 1.ProcessSettings（）在Kendo.Mvc.UI.WidgetBase.RenderHtml（TextWriter writer）在Kendo.Mvc.UI.WidgetBase.ToHtmlString（）在Kendo.Mvc.UI.Fluent.WidgetBuilderBase 2.WriteTo(TextWriter writer, HtmlEncoder encoder) at Microsoft.AspNetCore.Mvc.ViewFeatures.Internal.ViewBuffer.WriteToAsync(TextWriter writer, HtmlEncoder encoder) at Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderLayoutAsync(ViewContext context, ViewBufferTextWriter bodyWriter) at Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderAsync(ViewContext context) at Microsoft.AspNetCore.Mvc.ViewFeatures.ViewExecutor.ExecuteAsync(ViewContext viewContext, String contentType, Nullable 1 statusCode处）在Microsoft.AspNetCore.Mvc.ViewFeatures.ViewExecutor.ExecuteAsync（ActionContext actionContext，IView视图，ViewDataDictionary viewData，ITempDataDictionary tempData，字符串contentType，可为空的1 statusCode）在Microsoft.AspNetCore.Mvc.ViewFeatures.ViewResultExecutor.ExecuteAsync（ActionContext上下文，ViewResult结果）在Microsoft.AspNetCore.Mvc.ViewResult.ExecuteResultAsync（ActionContext上下文）在Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeResultAsync（IActionResult结果）在Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeNextResultFilterAsyncTFilter，TFilterAsync 在Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Rethrow（ResultExecutedContext上下文）在Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.ResultNext [TFilter，TFilterAsync]（状态和下一个，范围和范围，对象和状态，布尔值和isCompleted）在Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeResultFilters（）在Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeNextResourceFilter（）在Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Rethrow（ResourceExecutedContext上下文）在Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Next（状态和下一个，范围和范围，对象和状态，布尔值和已完成）在Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeFilterPipelineAsync（）在Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeAsync（）在Microsoft.AspNetCore.Routing.EndpointMiddleware.Invoke（HttpContext httpContext）在Microsoft.AspNetCore.Routing.EndpointRoutingMiddleware.Invoke（HttpContext httpContext）在Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware.Invoke（HttpContext上下文）在Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke（HttpContext上下文）

编辑器模板：

@model TimeSpan    
@{
    if (Model != null) {
        @Html.Kendo().IntegerTextBoxFor(model => model.Days).HtmlAttributes(new { style = "width: 30px;" }).Spinners(false)@:.
        @Html.Kendo().IntegerTextBoxFor(model => model.Hours).HtmlAttributes(new { style = "width: 30px;" }).Spinners(false).Max(23)@: :
        @Html.Kendo().IntegerTextBoxFor(model => model.Minutes).HtmlAttributes(new { style = "width: 30px;" }).Spinners(false).Max(59)@: :
        @Html.Kendo().IntegerTextBoxFor(model => model.Seconds).HtmlAttributes(new { style = "width: 30px;" }).Spinners(false).Max(59)
    }
}

kendo ui网格呈现编辑器模板：

@(
        Html.Kendo().Grid<MctDataViewModel>().Name("grid")
        .ToolBar(toolbar => toolbar.Create())
        .Pageable()
        .Scrollable()
        .Editable(e => e.Enabled(true).Mode(GridEditMode.InLine))
        .Columns(c => { c.Command(cmd => { cmd.Edit().Text(" "); cmd.Destroy().Text(" "); }) ;
            c.Bound(m => m.Id);
            c.Bound(m => m.SequenceNumber);
            c.Bound(m => m.SequenceName);
            c.Bound(m => m.StepNumber);
            c.Bound(m => m.StepName);
            c.Bound(m => m.ParallelNumber);
            c.ForeignKey(m => m.RowType, (System.Collections.IEnumerable)ViewData[nameof(MCTRowType)], "Key", "Value");
            c.ForeignKey(m => m.TimeType, (System.Collections.IEnumerable)ViewData[nameof(MCTTimeType)], "Key", "Value");
            c.Bound(m => m.TimeNeeded).EditorTemplateName("TimeSpanNumeric");
            c.ForeignKey(m => m.InventoryType, (System.Collections.IEnumerable)ViewData[nameof(MCTInventoryType)], "Key", "Value").EditorTemplateName("GridNullableForeignKey");
            c.Bound(m => m.ByInventoriesUnits);
            c.Bound(m => m.ByInventoriesUnitsPerDay);
        })
        .DataSource(ds => ds.Ajax()
            .Sort(s => { s.Add(m => m.SequenceNumber); s.Add(m => m.StepNumber); })
            .Create(c => c.Action(nameof(MCT.Controllers.HomeController.CreateGridDate), "Home"))
            .Read(r => r.Action(nameof(MCT.Controllers.HomeController.ReadGridData), "Home"))
            .Update(u => u.Action(nameof(MCT.Controllers.HomeController.UpdateGridDate), "Home"))
            .Destroy(d => d.Action(nameof(MCT.Controllers.HomeController.DeleteGridDate), "Home"))
            .Model(m => {
                m.Id(mct => mct.Id);
                m.Field(f => f.TimeNeeded).DefaultValue(TimeSpan.Zero); })
        )
)

服务配置：

public void ConfigureServices(IServiceCollection services) {
    // Add framework services.
    services
        .AddMvc(options => {
            options.ModelBinderProviders.Insert(0, new TimeSpanModelBinderProvider());
        })
        .SetCompatibilityVersion(CompatibilityVersion.Version_2_2)
        // Maintain property names during serialization. See:
        // https://github.com/aspnet/Announcements/issues/194
        .AddJsonOptions(options => options.SerializerSettings.ContractResolver = new DefaultContractResolver());

    // Add Kendo UI services to the services container
    services.AddKendo();
}

即使告诉框架在视图模型中显式使用modelbinder，也不会改变问题。

    [Microsoft.AspNetCore.Mvc.ModelBinder(typeof(TimeSpanModelBinder))]
    public TimeSpan TimeNeeded { get; set; }

永远不会调用模型联编程序。从用于导航到该页面的页面上的另一个请求中调用modelbinderprovider。因此，提供者的注册似乎有效。

我想念什么？如何获得asp.net核心以呈现自定义编辑器？

亲切的问候伯恩德

Kendo UI ASP.NET Core：自定义编辑器模板中的NullReferenceException

0 个答案: