在局部视图修改MVC 3 ViewBag不会坚持到_Layout.cshtml [英] Modifying MVC 3 ViewBag in a partial view does not persist to the _Layout.cshtml

问题描述

我使用MVC 3用的Razor视图引擎。我想设置一个局部视图内的ViewBag一些值，并希望在我_Layout.cshtml检索这些值。例如，当您设置一个默认的ASP.NET MVC 3项目你在/查看/共享文件夹中的文件_Layout.cshtml。在_Layout.cshtml页面标题设置是这样的：

I am using MVC 3 with the Razor view engine. I want to set some values in the ViewBag inside a Partial View and want retrieve those values in my _Layout.cshtml. For example, when you setup a default ASP.NET MVC 3 project you get a _Layout.cshtml file in the "/Views/Shared" folder. In that _Layout.cshtml the Page Title is set like this:

<title>@ViewBag.PageTitle</title>

然后在/Views/Home/About.cshtml查看ViewBag的内容被修改：

Then in "/Views/Home/About.cshtml" view the contents of the ViewBag are modified:

@{
    ViewBag.Title = "About Us";
}

这工作正常。当关于视图呈现在页面的标题是关于我们。所以，现在我想渲染我关于视图内的局部视图，我想修改我ViewBag.Title局部视图中。 （/Views/Shared/SomePartial.cshtml）

This works fine. When the About view is rendered the page title is "About Us". So, now I want to render a Partial view inside my About view and I want to modify the ViewBag.Title inside my Partial view. ("/Views/Shared/SomePartial.cshtml")

@Html.Partial("SomePartial")

在此局部视图我有这样的code：

In this Partial view I have this code:

@{
    ViewBag.Title = "About Us From The Partial View";
}

当我调试这个code我看到ViewBag.Title被置为关于我们，然后在局部视图我看到它得到重置为关于我们从局部视图，但当code打_Layout.cshtml它可以追溯到关于我们。

When I debug this code I see the ViewBag.Title get set to "About Us" and then in the Partial view I see it get reset to "About Us From The Partial View", but when the code hits the _Layout.cshtml it goes back to "About Us".

这是否意味着，如果ViewBag的内容在一个局部视图被修改，将不会出现这些变化（可访问），在主视图（About.cshtml）或_Layout.cshtml？

Does this mean that if the contents of the ViewBag are modified in a Partial view, those changes will not appear(be accessible) in the main view (About.cshtml) or the _Layout.cshtml?

在此先感谢！

推荐答案

我也有这个问题，找不到任何整洁，明显的解决方案。

I also had this problem, and couldn't find any neat and obvious solution.

我想出了解决的办法是实施返回您定义的PageData类的HTML扩展方法，包含任何你需要的数据：

The solution I came up with was to implement an Html extension method that returns a 'PageData' class that you define, containing whatever data you need:

    [ThreadStatic]
    private static ControllerBase pageDataController;
    [ThreadStatic]
    private static PageData pageData;

    public static PageData GetPageData(this HtmlHelper html) {
        ControllerBase controller = html.ViewContext.Controller;
        while (controller.ControllerContext.IsChildAction) {
            controller = controller.ControllerContext.ParentActionViewContext.Controller;
        }
        if (pageDataController == controller) {
            return pageData;
        } else {
            pageDataController = controller;
            pageData = new PageData();
            return pageData;
        }
    }

有认定为当前请求顶层控制器，每个所述方法被调用同一HTTP请求之内的时间返回相同PageData对象。它创建了一个新的对象PageData第一次它被称为一个新的HTTP请求。​​

It finds the top-level controller for the current request, and returns the same PageData object every time the method is called within the same HTTP request. It creates a new PageData object the first time it is called in a new HTTP request.

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