一个ViewStartPage只能与从WebViewPage或另一ViewStartPage派生的页使用 [英] A ViewStartPage can be used only with with a page that derives from WebViewPage or another ViewStartPage

问题描述

由于一些生活必需品我创建自己的自定义视图开始，如下所示：

Due to some necessities I created my own custom View Start as follows:

public abstract class MyViewStart : System.Web.Mvc.ViewStartPage {
    public My.Helpers.ThemeHelper Themes { get; private set; }

    public MyViewStart() : base() {
        Themes = new Helpers.ThemeHelper(base.ViewContext)
    }
}

我们需要的是，在_ViewStart我需要做一些布局文件的发现依赖
的主题，它的作用是不相关的问题。

The need is that in the _ViewStart I need to do some layout file finding that depends on the theme, what it does is irrelevant to the problem.

我的视图/共享/ _ViewStart.cshtml看起来像这样（东西无关删除）：

My Views/Shared/_ViewStart.cshtml looks like this (irrelevant stuff removed):

@inherits MyNamespace.MyViewStart
@{
    Layout = Themes.ThemeLayout;
}

因此​​，我们有从标准ViewStartPage派生的自定义ViewStart类。该标准_ViewStart.cshtml是ViewStartPage。新_ViewStart.cshtml是MyViewStart页这又是一个标准的ViewStartPage因此所有覆盖在继承。

So, we have a custom ViewStart class that derives from the standard ViewStartPage. The standard _ViewStart.cshtml is a ViewStartPage. The new _ViewStart.cshtml is a MyViewStart page which in turn is a standard ViewStartPage so all is covered in the inheritance.

然而，当我运行该应用程序，我得到的错误：

However, when I run the application I get the error:

一个ViewStartPage只能用从WebViewPage或其他ViewStartPage派生的页面中使用

A ViewStartPage can be used only with with a page that derives from WebViewPage or another ViewStartPage

这是由主题=新Helpers.ThemeHelper我的自定义视图启动类的构造函数抛出线。那么，为什么它抛出异常时，我的自定义视图启动类ViewStartPage ???

which is thrown by the "Themes = new Helpers.ThemeHelper" line in the constructor of my custom view start class. So, why does it throws that exception when my custom view start class IS a child of ViewStartPage ???

推荐答案

您无法访问ViewContext在构造函数中，但如果你重写ExecutePageHierarchy你可以做它。我修改了code这样的，使其工作：

You cannot access the ViewContext in the constructor, but if you override ExecutePageHierarchy you can do it there. I modified your code like this to make it work:

public abstract class MyViewStart : System.Web.Mvc.ViewStartPage {
    public My.Helpers.ThemeHelper Themes { get; private set; }

    public override void ExecutePageHierarchy()
    {
        this.Themes = new Helpers.ThemeHelper(this.ViewContext);
        base.ExecutePageHierarchy();
    }
}

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