html.partial的一個bug?

主視圖：

 @Html.Partial("SeriesChartPartial", ViewBag.deviceEveyDayActivity as List<SeriesChartVM>)

分布視圖：

  @using Magmoud.Web.ViewModels@model List<SeriesChartVM>@(Html.Telerik().Chart(Model).Legend(false).Name("SingleChart")           .Series(series =>                       {                               if (ViewBag.IOSSelect == "true")                               {                                   series.Line(s => s.IOSCount).Color(UISetting.IOSCOLOR);                               }                               if (ViewBag.AndroidSelect == "true")                               {                                   series.Line(s => s.AndroidCount).Color(UISetting.ANDROIDCOLOR);                               }                               if (ViewBag.WindowsSelect == "true")                               {                                   series.Line(s => s.WindowsCount).Color(UISetting.WINDOWSCOLOR);                               }                       }).CategoryAxis(axis => axis                                                           .Categories(s => s.XData)           )           .ValueAxis(axis => axis                                  .Numeric()).Tooltip(true))

這樣是沒問題的。

但是如果改變主視圖，嘗試使用html.partial的第三個重載：

@Html.Partial("SeriesChartPartial", ViewBag.deviceEveyDayActivity as List<SeriesChartVM>,    new ViewDataDictionary {                             { "chartType", ViewBag.deviceEveyDayActivityChartType as string },                            })

VS沒有報異常，但分部視圖就無法渲染了。猜測是ViewBag.IOSSelect等沒有資料，於是將主視圖改為：

@Html.Partial("SeriesChartPartial", ViewBag.singleViewDuration as List<SeriesChartVM>,    new ViewDataDictionary {                            { "iosSelect", ViewBag.iosSelect },                           { "androidSelect", ViewBag.androidSelect },                           { "windowsSelect", ViewBag.windowsSelect }                           })

分部視圖改為：

@using Magmoud.Web.ViewModels@model List<SeriesChartVM>@(Html.Telerik().Chart(Model).Legend(false).Name(ViewData["name"] as string)           .Series(series =>                       {                               if (ViewData["iosSelect"] as string == "true")                               {                                   series.Line(s => s.IOSCount).Color(UISetting.IOSCOLOR);                               }                               if (ViewData["androidSelect"] as string == "true")                               {                                   series.Line(s => s.AndroidCount).Color(UISetting.ANDROIDCOLOR);                               }                               if (ViewData["windowsSelect"] as string == "true")                               {                                   series.Line(s => s.WindowsCount).Color(UISetting.WINDOWSCOLOR);                                }                       }).CategoryAxis(axis => axis                                                           .Categories(s => s.XData)           )           .ValueAxis(axis => axis                                  .Numeric()).Tooltip(true))

就運行正常了。原因不知。