为什么 ViewBag 数据为空？

Question

我正在尝试使用 MVC 和 iText 从我的网页创建一个 pdf，但是当我到达视图时，ViewBag 数据为空。

在 Controller 中，ViewBag 仍然有值。

为什么ViewBag数据为空？

在视图中启动：

<td><span>
    <a href='<%: Url.Action("HitlijstNaarPdf", new { AID_Hitlijst = ViewBag.Huidig })%>' target="_blank">
        Download lijst
    </a></span>
</td>

在控制器中调用结果

public FileStreamResult HitlijstNaarPdf(int? AID_Hitlijst = 0)
{
    SelectPeriode(AID_Hitlijst);
    GetHitlijstSettings();
    var model = new HitlijstModel();
    string sHtmlInhoud= this.RenderView("Index", model);

    FileStreamResult result = PDFGenerator(sHtmlInhoud);
    return result;
}

private void GetHitlijstSettings()
{
    ViewBag.Datum = FHitlijstSettings.Datum;
    ViewBag.Jaar = FHitlijstSettings.Jaar;
    ViewBag.Week = FHitlijstSettings.Week;
}

在 class ControllerExtensions 中：

public static class ControllerExtensions
{
    public static string RenderView(this Controller controller, string viewName, object model)
    {
        return RenderView(controller, viewName, new ViewDataDictionary(model));
    }

    public static string RenderView(this Controller controller, string viewName, ViewDataDictionary viewData)
    {
        var controllerContext = controller.ControllerContext;

        var viewResult = ViewEngines.Engines.FindView(controllerContext, viewName, null);

        StringWriter stringWriter;

        using (stringWriter = new StringWriter())
        {
            var viewContext = new ViewContext(
                controllerContext,
                viewResult.View,
                viewData,
                controllerContext.Controller.TempData,
                stringWriter);

            // Here viewResult.ViewBag.Week still has data
            // by debugging you see:
            // viewResult.ViewBag.Week = 14;
            // viewResult.ViewBag.Datum = "maandag 6 april 1987";
            viewResult.View.Render(viewContext, stringWriter);
            viewResult.ViewEngine.ReleaseView(controllerContext, viewResult.View);
        }

        return stringWriter.ToString();
    }
}

而当系统returns到View时(ViewBag.Week <=> null):

<th class="hitlijst_datum">Hitlijst&nbsp;-&nbsp;nummer&nbsp;<%: ViewBag.Week %>&nbsp;-&nbsp;<%: ViewBag.Datum  %></th>

您收到以下消息：

以下方法或属性之间的调用不明确：'System.IO.TextWriter.Write(string, params object[])' 和 'System.IO.TextWriter.Write(char[])'

我试过：Html.Raw 和 ToString => Html.Raw(ViewBag.Week.ToString()) 也一样，但这也不起作用。我必须做什么才能确保 ViewBag 在 View 中不为空？

Answer 1

答案如下：http://weblog.west-wind.com/posts/2012/May/30/Rendering-ASPNET-MVC-Views-to-String。我用这个来源替换了 ControllerExtensions。它有效。如果有人能告诉我，为什么通过 ControllerExtensions class 的 ViewBag 消失了。高兴听到。

为什么 ViewBag 数据为空？

Why is the ViewBag data empty?

html

c#

asp.net-mvc

itext